How does lysine react with various chemical agents. What are the key nucleophilic substitution reactions of lysine. How can lysine be modified for protein labeling and crosslinking applications.

Nucleophilic Substitution Reactions of Lysine

Lysine is a versatile amino acid that participates in numerous chemical reactions due to its nucleophilic ε-amino group. Understanding these reactions is crucial for biochemists and researchers working with protein modifications. Let’s explore some of the most important nucleophilic substitution reactions involving lysine:

Reaction with Anhydrides

One of the fundamental reactions of lysine is its interaction with anhydrides in a nucleophilic substitution reaction, also known as acylation. This reaction is widely used in protein chemistry for various purposes, including:

• Protein labeling
• Crosslinking
• Studying protein structure and function

How does this reaction proceed? The nucleophilic ε-amino group of lysine attacks the electrophilic carbonyl carbon of the anhydride, resulting in the formation of an amide bond and the release of a carboxylic acid.

Reversible Reaction with Methylmaleic Anhydride

Lysine undergoes a reversible nucleophilic substitution reaction with methylmaleic anhydride, also known as citraconic anhydride. This reaction is particularly useful in protein chemistry because:

1. It allows for temporary modification of lysine residues
2. The modification can be reversed under mild conditions
3. It provides a means to protect lysine residues during certain chemical procedures

Why is the reversibility of this reaction important? It enables researchers to modify proteins temporarily and then restore them to their original state, which is crucial for studying protein function without permanent alterations.

Specific Reactions with Imidate Compounds

Lysine exhibits high specificity and yield in its reaction with ethylacetimidate, a compound similar to ethyl acetate but with an imido group replacing the carbonyl oxygen. This nucleophilic substitution reaction results in the formation of an amidino group.

Mechanism of Ethylacetimidate Reaction

The reaction proceeds as follows:

1. The ε-amino group of lysine attacks the carbon of the imidate group
2. Ethanol is expelled as a leaving group
3. An amidino group forms, containing two nitrogen atoms attached to the carbon

Why is this reaction significant in biochemistry? The high specificity and yield make it an excellent tool for selective modification of lysine residues in proteins, allowing researchers to study protein structure and function with precision.

Guanidination of Lysine

Another important reaction of lysine involves its interaction with O-methylisourea in a nucleophilic substitution reaction. This process, known as guanidination, results in the formation of a guanidino group.

Steps in the Guanidination Process

The reaction occurs as follows:

1. The ε-amino group of lysine attacks the carbon of O-methylisourea
2. Methanol is expelled as a leaving group
3. A guanidino group forms, containing three nitrogen atoms attached to the carbon

What makes the guanidino group unique? Its structure, with three nitrogen atoms attached to a central carbon, gives it distinct chemical properties that can be exploited in various biochemical applications.

Lysine Modifications for Protein Labeling

Several reactions of lysine are specifically used for protein labeling and analysis. These include:

Reaction with FDNB (Sanger’s Reagent)

Lysine reacts with fluorodinitrobenzene (FDNB), also known as Sanger’s reagent, in a nucleophilic aromatic substitution reaction. This reaction forms 2,4-DNP-lysine, which is widely used in protein sequencing and analysis.

Reaction with TNBS

Similar to the FDNB reaction, lysine also reacts with trinitrobenzenesulfonate (TNBS) to form TNB-lysine. This reaction is commonly used in quantifying available lysine residues in proteins.

Dansylation Reaction

Lysine undergoes a nucleophilic substitution reaction with dimethylaminonapthalenesulfonylchloride (Dansyl Chloride). This reaction is particularly useful for:

• Fluorescent labeling of proteins
• Enhancing protein detection in various analytical techniques
• Studying protein structure and interactions

How does dansylation improve protein analysis? The fluorescent properties of the dansyl group allow for sensitive detection and visualization of proteins in various experimental settings.

Imine Formation and Reduction

Lysine exhibits high specificity in its reaction with aldehydes to form imines, also known as Schiff bases. This reaction is significant in various biological processes and has applications in protein modification and crosslinking.

Mechanism of Imine Formation

The reaction proceeds as follows:

1. The ε-amino group of lysine attacks the carbonyl carbon of the aldehyde
2. Water is eliminated, resulting in the formation of an imine (C=N bond)
3. The imine can be reduced to form a stable secondary amine

What makes this reaction particularly useful? The ability to reduce the imine to a stable secondary amine allows for permanent modification of lysine residues, which is valuable in various biochemical applications.

Reduction of Imines

The imines formed by lysine can be reduced using specific reducing agents:

• Sodium borohydride (NaBH4)
• Sodium cyanoborohydride (NaBH3CN)

Why use cyanoborohydride instead of borohydride? Cyanoborohydride is a milder reducing agent that selectively reduces imines without affecting other functional groups in proteins, making it ideal for specific modifications.

Applications of Lysine Modifications in Biochemistry

The various reactions of lysine have numerous applications in biochemistry and molecular biology research:

Protein Crosslinking

Lysine modifications are extensively used for protein crosslinking, which is crucial for:

• Studying protein-protein interactions
• Stabilizing protein complexes
• Developing novel biomaterials

How does crosslinking provide insights into protein interactions? By chemically linking proteins that are in close proximity, researchers can capture and study transient or weak interactions that might be difficult to observe otherwise.

Protein Labeling for Detection and Purification

The ability to modify lysine residues allows for various labeling strategies:

• Fluorescent labeling for microscopy and flow cytometry
• Affinity tagging for protein purification
• Radiolabeling for sensitive detection in biological samples

Why is selective labeling important in protein studies? It allows researchers to track specific proteins in complex biological systems, providing insights into their localization, interactions, and functions.

Protein Pegylation

Lysine modifications are used in protein pegylation, a process where polyethylene glycol (PEG) chains are attached to proteins. This technique has several benefits:

• Increasing protein stability
• Extending the half-life of therapeutic proteins
• Reducing immunogenicity of protein drugs

How does pegylation improve protein therapeutics? By attaching PEG chains to lysine residues, the size and properties of proteins can be altered, leading to improved pharmacokinetics and reduced clearance from the body.

Challenges and Considerations in Lysine Modifications

While lysine modifications are powerful tools in biochemistry, there are several challenges and considerations to keep in mind:

Specificity and Selectivity

One of the main challenges in lysine modifications is achieving specificity for a particular lysine residue in a protein. Proteins often contain multiple lysine residues, and controlling which ones react can be difficult.

What strategies can improve specificity? Researchers often use a combination of approaches:

• pH control to exploit differences in lysine pKa values
• Steric factors to target more accessible lysines
• Site-directed mutagenesis to remove unwanted lysines

Maintaining Protein Function

Another important consideration is preserving the protein’s native function after modification. Lysine residues can be crucial for protein activity, and their modification may lead to loss of function.

How can researchers modify lysines while preserving function? Some approaches include:

• Careful selection of modification sites based on structural data
• Using reversible modifications for temporary alterations
• Employing mild reaction conditions to minimize protein denaturation

Quantification and Characterization

Accurately quantifying and characterizing lysine modifications can be challenging, especially in complex protein samples. Researchers need to employ various analytical techniques to assess the extent and specificity of modifications.

What methods are commonly used for this purpose?

• Mass spectrometry for precise identification of modified sites
• Spectrophotometric assays for quantifying overall modification levels
• Functional assays to assess the impact on protein activity

Future Directions in Lysine Modification Research

As our understanding of protein chemistry advances, new frontiers in lysine modification research are emerging:

Site-Specific Modifications

Researchers are developing increasingly sophisticated methods for site-specific lysine modifications. These approaches aim to target individual lysine residues with high precision, allowing for more controlled protein engineering.

What technologies are driving this progress?

• Genetic code expansion for incorporating unnatural amino acids
• Enzyme-mediated modifications for improved specificity
• Computational design of site-specific reagents

Bioorthogonal Chemistry

The field of bioorthogonal chemistry is opening new possibilities for lysine modifications in living systems. These reactions can occur in biological environments without interfering with native biochemical processes.

How does bioorthogonal chemistry enhance lysine modifications?

• Allows for in vivo protein labeling and tracking
• Enables dynamic studies of protein function in living cells
• Provides new tools for drug delivery and targeted therapies

Therapeutic Applications

Lysine modifications are increasingly being explored for therapeutic applications, particularly in the development of antibody-drug conjugates (ADCs) and other targeted therapies.

What makes lysine modifications attractive for therapeutic development?

• Ability to attach drug molecules to antibodies or other targeting proteins
• Potential for creating more stable and effective protein therapeutics
• Opportunities for developing novel drug delivery systems

As research in lysine modifications continues to advance, we can expect to see new and innovative applications in fields ranging from basic biochemistry to medical therapeutics. The versatility and reactivity of lysine make it a key player in the ongoing revolution in protein engineering and chemical biology.

2.1.5: A5. Reactions of Lysine

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• Henry Jakubowski
• College of St. Benedict/St. John’s University

• reacts with anhydride in a nucleophilic substitution reaction (acylation).
• reacts reversibly with methylmaleic anhydride (also called citraconic anhydride) in a nucleophilic substitution reaction.
• reacts with high specificity and yield toward ethylacetimidate in a nucleophilic substitution reaction (ethylacetimidate is like ethylacetate only with a imido group replacing the carbonyl oxygen). Ethanol leaves as the amidino group forms. (has two N -i.e. din – attached to the C)

Figure: LYSINE REACTIONS 2

• reacts with O-methylisourea in a nucleophilic substitution reaction. with the expulsion of methanol to form a guanidino group (has 3 N attached to C, nidi)
• reacts with fluorodintirobenzene (FDNB or Sanger’s reagent) or trinitrobenzenesulfonate (TNBS, as we saw with the reaction with phosphatidylethanolamine) in a nucleophilic aromatic substitution reaction to form 2,4-DNP-lysine or TNB-lysine.
• reacts with Dimethylaminonapthelenesulfonylchloride (Dansyl Chloride) in a nucleophilic substitution reaction.

Figure: LYSINE REACTIONS 3

• reacts with high specificity toward aldehydes to form imines (Schiff bases), which can be reduced with sodium borohydride or cyanoborohydride to form a secondary amine.

• Prof. Henry Jakubowski (College of St. Benedict/St. John’s University)

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Reactions of Lysine



Reactions of Lysine

BIOCHEMISTRY – DR. JAKUBOWSKI

Last Update: 
02/27/16

•  reacts with anhydride in a nucleophilic substitution reaction
  (acylation).
• reacts reversibly with methylmaleic anhydride (also called
  citraconic anhydride) in a nucleophilic substitution reaction.
• reacts with high specificity and yield toward ethylacetimidate in a
  nucleophilic substitution reaction (ethylacetimidate  is like
  ethylacetate only with a imido group replacing the carbonyl oxygen).
  Ethanol leaves as the amidino group forms. (has two N -i.e. din –
  attached to the C)

Figure:  LYSINE REACTIONS 2

• reacts with O-methylisourea in a nucleophilic substitution reaction.
  with the expulsion of methanol to form a guanidino group (has 3 N
  attached to C, nidi)
• reacts with fluorodintirobenzene (FDNB or Sanger’s reagent) or
  trinitrobenzenesulfonate (TNBS, as we saw with the reaction with
  phosphatidylethanolamine) in a nucleophilic aromatic substitution
  reaction to form 2,4-DNP-lysine or TNB-lysine.
• reacts with Dimethylaminonapthelenesulfonylchloride
  (Dansyl Chloride) in a nucleophilic substitution reaction.

Figure:  LYSINE REACTIONS 3

• reacts with high specificity toward aldehydes to form imines (Schiff
  bases), which can be reduced with sodium borohydride or cyanoborohydride
  to form a secondary amine.

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Argumentation of symptomatic therapy of acute tonsillopharyngitis | Morozova S.V.

Diagnosis and treatment of acute infectious and inflammatory diseases of the pharynx is one of the main problems solved by practical otorhinolaryngology. The pharynx, located at the junction of the respiratory and digestive tracts, is subject to the action of numerous damaging factors that can disrupt the protective and adaptive reactions and the functioning of the mucous membrane and the lymphoid apparatus of the pharynx.

The reasons contributing to the occurrence of pharyngeal pathological changes are numerous and varied: exposure to an infectious agent, diseases of the gastrointestinal tract (GIT), diseases of the teeth and periodontium, smoking, adverse environmental, professional and domestic factors, diet errors, trauma.
It is important to note the medical and social significance of the problem. Thus, acute respiratory viral diseases, the annual incidence of which is up to 8 people per 1,000 population, are accompanied by inflammation in the respiratory tract affecting the pharynx [4]. A high level of morbidity leads to a large number of outpatient visits of the working population and students, an increase in the level of temporary disability both in the number of cases and in the number of days missed due to illness and care, to significant expenses for the purchase of medicines – within the family budget and significant financial losses – on a national scale.
Undoubtedly, one of the most common diseases of the pharynx is acute tonsillopharyngitis, which is confirmed by the high level of morbidity and the appeal of patients to general practitioners and otorhinolaryngologists. In the implementation of the disease, the leading role belongs to the infectious factor (viruses, bacteria, fungi) with a significant predominance of viruses (adenoviruses, rhinoviruses, coronaviruses, influenza viruses, parainfluenza viruses, Coxsackie A viruses, etc.). According to modern domestic scientific and clinical studies, which allow a clear idea of ​​the nature and sensitivity of the key bacterial pathogens of acute infectious and inflammatory diseases of the pharynx (microorganisms isolated with a clinically significant degree of contamination over 104 CFU / ml), the leading role is played by Streptococcus pyogenes. In patients with bacterial tonsillitis, the inoculation of group A β-hemolytic streptococcus (GABHS) reaches 80–100%, less often group C and G streptococci, Corynebacterium diphtheriae, Neisseria gonorrhoeae, Arcanobacterium haemolyticum are isolated [4, 7].
In the practice of a doctor, it is necessary to take into account the importance of identifying acute “streptococcal” tonsillopharyngitis, when the disease has a severe, protracted course, there are cases of systemic inflammatory response syndrome (SIRS). With tonsillopharyngitis caused by GABHS, there is a high probability of developing severe complications and life-threatening conditions, such as meningitis, pneumonia, sepsis, toxic shock syndrome, rheumatic fever, post-streptococcal glomerulonephritis, etc.
In acute “streptococcal” tonsillopharyngitis, the most likely routes of infection are contact and airborne. The reservoir is, as a rule, a sick person or a carrier; colonization of the pathogen is possible on the skin, mucous membrane of the pharynx and nasal cavity. An alimentary route of infection is possible – with improper storage of food, in particular dairy products. Predisposing factors for the onset of the disease are local and general hypothermia, a decrease in general and local immunity, and sometimes mechanical trauma to the tonsils.
The disease is characterized by a sudden onset, intense sore throat, most pronounced when swallowing, a feeling of dryness, soreness, sore throat, moderate (febrile) fever, headache. Patients note general weakness, malaise, loss of appetite, aching pain in the limbs. The “tonsillar” lymph nodes enlarge and become painful on palpation. With pharyngoscopy, a bright diffuse reddening of the mucous membrane of the pharynx is determined, changes in the palatine tonsils may correspond to one of the forms of primary (vulgar) tonsillitis: the palatine tonsils are enlarged, edematous and hyperemic (catarrhal tonsillitis), yellowish-white plaques are visible on the surface of the palatine tonsils (lacunar tonsillitis). ), festering follicles in the form of small yellowish vesicles (follicular tonsillitis).
The McIsaac scale helps to determine the degree of probability of streptococcal etiology of acute tonsillopharyngitis at the first stage of assessing the patient’s condition, based on the clinical manifestations of the disease. Analysis and quantitative (scoring) assessment of such criteria as fever, cough, condition of the cervical lymph nodes, palatine tonsils, patient’s age allow, with a high degree of probability, to assess the risk of streptococcal infection and determine the tactics of treatment and diagnostic measures [8]. At the same time, patients with infectious and inflammatory diseases of the pharynx, of course, need a multifaceted examination, including, in particular, such informative studies as bacteriological and immunological, which makes it possible to fully diagnose both the disease and the diagnosis of the patient. It should be recognized that in modern conditions, laboratory information is extremely important for high-quality clinical diagnostics [3].
The bacteriological method is the isolation of a pure culture of the pathogen and its identification, determination of its sensitivity to antibiotics and other chemotherapeutic drugs. Both the classical culture method by inoculation and express methods for identifying group A streptococci are used: immunochromatographic rapid test for GABHS antigens in throat swabs, methods for detecting pathogen antigens (enzyme-linked immunosorbent assay and direct immunofluorescence), methods for detecting pathogen DNA (polymerase chain reaction ), which are characterized by high sensitivity and absolute specificity.
Immunological examination allows diagnosing primary and secondary immunological deficiency. Secondary (acquired) immunological deficiency – damage to the initially unchanged immune system under the influence of various exogenous factors (infections, tumors, renal failure, long-term use of glucocorticosteroids, cytostatics). Primary (congenital) immunological deficiency is much less common – the inability of the body to implement one or another link of the immune response due to a genetically determined defect or impaired development of the lymphoid system in ontogenesis.
Diagnostics involves carrying out tests of the 1st level, which include the determination of the absolute and relative number of lymphocytes, T- and B-lymphocytes, the level of serum lg (IgM, IgG, IgA), phagocytic activity of leukocytes, as well as tests of the 2nd level: determination regulatory subpopulations (T-helpers, T-suppressors), interleukin-producing activity of cells, assessment of the proliferative activity of T- and B-lymphocytes in the reaction of blast transformation, killer activity of lymphocytes, identification of immune complexes, etc.
An important stage in the diagnosis of acute tonsillopharyngitis is differential diagnosis with diseases that have a similar symptom complex (infectious mononucleosis, diphtheria). Children’s respiratory tract infections (scarlet fever, measles) are accompanied by catarrhal oropharyngeal changes. Changes in the pharyngeal mucosa in diseases of the gastrointestinal tract (chronic gastritis, peptic ulcer, oral dysbacteriosis, gastroesophageal reflux disease, cholecystitis, pancreatitis) are very common [2].
Often, the initial and determining factor, subjectively regarded as a state of ill health, which forces patients to seek medical help, is the occurrence and severity of pain when swallowing, as well as soreness, perspiration, dry paroxysmal cough. Among the extremely numerous and diverse causes of sore throat (neuralgia of the glossopharyngeal nerve, spinal diseases, cardiovascular diseases (angina pectoris, myocardial infarction), thyroiditis, injuries and foreign bodies of the pharynx and esophagus, mental disorders, AIDS, oropharyngeal cancer, etc. ) tonsillopharyngitis is one of the most common etiological factors [6, 11].
The appearance of acute pain in the throat performs a signal function in case of inflammation of the pharynx, indicates the presence of a damaging factor, initiates protective-compensatory-adaptive processes in the body, therefore, in relation to acute tonsillopharyngitis, the expression that has become a popular expression is quite appropriate: “Pain is the watchdog of health.” However, with a sharp intensity and duration of pain, overstrain occurs, the patient develops a negative psycho-emotional state, he experiences painful anguish, and there is a clear motivation to eliminate pain as an extremely negative sensation. Pain disrupts the vital activity of the human body, inevitably affects the quality of life – an indicator directly related to the state of health, from the category of positive factors goes into the category of negative ones and needs to be eliminated [1, 5]. Pain sensations are characterized by a wide range of individual fluctuations. According to the severity of pain in acute infectious and inflammatory diseases of the pharynx, patients largely judge the severity of the disease and expect from the therapy, first of all, complete relief from pain.
These factors cannot be ignored when assessing the patient’s condition, developing therapeutic tactics and determining the effectiveness of the therapy. In this case, 2 main approaches are used: assessing the intensity of pain (“how much the patient suffers”) and assessing the impact of pain on well-being in general (“psychological state, quality of life”) [13]. Scales for the subjective assessment of the severity of pain by the patient at the time of the study are widely used in clinical practice: a visual analogue scale of pain, as well as a digital rating scale that has a number of advantages, consisting of 11 points, where 0 means no pain, 10 means pain that cannot be tolerated [ 15].
In the treatment of acute infectious and inflammatory diseases of the pharynx, drugs with antimicrobial, anti-inflammatory, analgesic, immunocorrective effects are currently used: antibacterial drugs, topical immunocorrective vaccine preparations, local antiseptics, decongestants, and hyposensitizing drugs [7]. In the complex of therapeutic measures for diseases of the pharynx, accompanied by pain, fever, an important role belongs to drugs that have a symptomatic therapeutic effect. Timely and adequate symptomatic therapy for acute tonsillopharyngitis is no less important than etiopathogenetic treatment, since its goals are to reduce the severity and eliminate the clinical manifestations of the disease, which have a significant negative impact on the patient’s daily life, to preserve his ability to perform household activities and social activity.
One of the most commonly used groups of drugs with analgesic, antipyretic and anti-inflammatory effects is non-steroidal anti-inflammatory drugs (NSAIDs). The appearance of pain during inflammatory processes is associated with the formation of prostaglandins at the site of inflammation, which irritate pain receptors and cause the appearance of a subjective sensation – pain. The principle of the analgesic action of NSAIDs is based on the suppression of the activity of cyclooxygenase types 1 and 2 (COX-1, COX-2) – the main enzymes necessary for the formation of prostaglandins.
A representative of this group is the drug OKI (lysine salt of ketoprofen). The drug has anti-bradykinin activity, stabilizes lysosomal membranes and delays the release of enzymes from them that contribute to tissue destruction in chronic inflammation, reduces the release of cytokines, and inhibits the activity of neutrophils. The lysine salt of Ketoprofen has anti-inflammatory, analgesic and antipyretic effects. The rapid onset of action is due to the higher solubility of the lysine salt of ketoprofen than that of unchanged ketoprofen, faster and more complete absorption of the active substance, which leads to the peak of its plasma concentration when taken orally after 15 minutes. The effect of the drug appears after 15-20 minutes. and persists for several hours, while unchanged ketoprofen reaches a maximum only after 60 minutes. after admission [12].
The OKI preparation is convenient to use, since it has various forms of release: granules for the preparation of a solution for oral administration, rectal suppositories (for the symptomatic treatment of inflammatory processes accompanied by fever and pain), and a topical solution (for the symptomatic treatment of inflammatory oropharyngeal diseases) . For oral administration, adults and children over 14 years of age, the contents of one two-volume sachet (full dose – 80 mg) should be dissolved in half a glass of drinking water and taken 3 times a day with meals. Children 6-14 years old and elderly patients are recommended to use the contents of 1/2 two-volume sachet (half the dose – 40 mg). Rectally, children aged 6–12 years are prescribed 1 suppository of OKI 60 mg 1–2 r./day; children over 12 years old – up to 3 rubles / day. Adults are prescribed 1 suppository of OKI 160 mg 2–3 rubles / day (elderly patients – no more than 2 suppositories / day). Locally, the drug is used in the form of a rinse solution, using in adults for 1 rinse 10 ml (5 injections) of an OKI solution, previously diluted with drinking water using the glass attached to the package. Adolescents over 12 years of age should use no more than 6 ml (3 injections) of the OKI solution for 1 rinse. The procedure must be carried out 2 rubles / day.
Contraindications to the use of the drug OKI are the “aspirin triad”, hypersensitivity to NSAIDs. The drug is also contraindicated for systemic use during exacerbation of peptic ulcer and ulcerative colitis, Crohn’s disease, diverticulitis, blood clotting disorders, severe renal dysfunction, in children under 6 years of age, in the third trimester of pregnancy and during lactation.
The analgesic effect of AEI is based on a triple mechanism: peripheral – through blockade of the arachidonic acid cycle, central – due to a decrease in the sensitivity of brain receptors and due to blockade of impulse transmission in the spinal cord. Comparative studies have shown that the analgesic efficacy of OCI is higher and manifests itself faster than that of ibuprofen and paracetamol [14]. The antipyretic effect of OCI is comparable to that of paracetamol and is more pronounced than that of ibuprofen and other NSAIDs [9]. According to the anti-inflammatory effect, OKI demonstrates high activity, significantly exceeding the activity of nimesulide [10]. Taking into account the fact that the use of nimesulide is limited in Europe, OKI as a lysine salt of ketoprofen is a worthy alternative to nimesulide, which minimizes the risk of developing adverse events from the liver.
An important aspect of the use of drugs for symptomatic therapy is their safety and tolerability. When prescribing NSAID therapy, special attention is paid to the undesirable effects inherent in the drugs of this group, primarily from the gastrointestinal tract and the hematopoietic system. Abdominal pain, diarrhea, exacerbation of gastritis or peptic ulcer, hepatic reactions – this is not a complete list of possible adverse events. In this aspect, the lysine salt of ketoprofen has advantages over ketoprofen, since it causes side effects much less frequently. Due to its chemical composition, OKI quickly mixes with a neutral pH environment and, due to this, has almost no irritating effect on the gastrointestinal mucosa. According to L. Bellussi et al. (1996), against the background of a 10-day intake of the OCI drug, the overall tolerability of therapy by patients and gastroscopy data were comparable with those when taking placebo [10].
To achieve the desired effect of pharmacotherapy, a patient with acute infectious and inflammatory diseases of the pharynx must follow the following basic recommendations: completely give up smoking and alcohol; exclude hot, cold, spicy, salty foods and drinks from the diet; in the absence of contraindications, conduct warming and distracting physiotherapy procedures at home.
Thus, the rational use of drugs for symptomatic therapy allows not only to achieve a positive clinical effect in the treatment of acute inflammatory diseases of the pharynx, but also to increase the level of patient satisfaction with the results of treatment.

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2. Vesyaeva A.A. Treatment of chronic pharyngitis associated with pathology of the gastrointestinal tract: Proceedings of the XVII Congress of Otorhinolaryngologists of Russia, Nizhny Novgorod, June 2006, pp. 165–166.
3. Menshikov V.V. (ed.), Dedov I.I., Makolkin V.I., Mukhin N.A. Clinical diagnosis – laboratory basis. M.: Labinform, 1997. 304 p.
4. Kolobukhina L.V. Viral infections of the respiratory tract // RMJ, 2000. V. 8. No. 13-14 (114-115). pp. 559–564.
5. Lerish R. Fundamentals of physiological surgery. Essays on the vegetative life of tissues / transl. from French B.M. Nikiforova M.: Medgiz, 1961. 292 p.
6. Morozova S.V. Pain in the throat: causes and possibilities of drug therapy // BC. 2005. V. 13. No. 21. S. 1447–1452.
7. Ryazantsev S.V. Etiopathogenetic therapy of acute pharyngitis: Method. recommendations. St. Petersburg: St. Petersburg Research Institute of Ear, Throat, Nose and Speech, 2008.
8. Shpynev K.V., Krechikov V.A. Modern approaches to the diagnosis of streptococcal pharyngitis // KMAH. 2007. V. 9. No. 1. S. 20–33.
9. D’Arienzo M. Summary of product characteristics // Drugs Exptl.Clin.Res. 1984 Vol. X(12) . R. 863–866.
10. Bellussi L. et al. Antiphlogistic therapy with ketoprofen lysine salt vs nimesulide in secretory otitis media, rhinitis/rhinosinusitis, pharyngitis/tonsillitis/tracheitis // Note di Terapia Otorinolaringol. 1996 Vol. 46. ​​R. 49–57.
11. Denk-Linnet D.-M., Mancusi G. Current diagnostics of swallowing disorders: the ENT specialists and phoniatricians role // European Archives of Oto-Rhino-Laringology and Head & Neck. June 2007 Vol. 264. Suppl. 1. HIC 5. R. 6.
12. Fatti F. Summary of product characteristics. Data on file, 1991.
13. Haefeli M., Elfering A., Aebi M. et al. What constitutes a good outcome in spinal surgery? A preliminary survey among spine surgeons of the SSE and European spine patients // Eur Spine J. 2008. 17. P. 104–116.
14. Ligniere G.C. et al. Ricenti Progressi in Medicina, II Pensiero Scientifico Editore. 1996 Vol. 87 (supplemento al #3).
15. Wewers M.E., Lowe N.K. A critical review of visual analogue scales in the measurement of clinical phenomena // Res Nurs Health. 1990 Vol. 13. R. 227–236.

Faculty of Biology St. Petersburg State University