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Symptoms of disease - violation of protein metabolism

Proteins are the most important biological substances of living organisms. They serve as the plastic material, of which are built cells, tissues and organs of the human body. Proteins are the basis of hormones, enzymes, antibodies and other entities that perform complex functions in human life (digestion, growth, reproduction, immune, etc.), promote normal exchange in the body of vitamins and mineral salts. Proteins involved in the formation of energy, especially in the period of the big energy costs, or when there is not enough in the diet of carbohydrates and fats. The energy value of 1 g of protein equals 4 calories (16,7 Kj).
With the lack of protein in the body there are serious violations of growth and development of children, changes in the liver adults, the activity of the glands of internal secretion, blood composition, the weakening of mental activity, reduced efficiency and resistance to infectious diseases.



Which diseases there is violation of protein metabolism

Since proteins occupy a Central position in the implementation of the processes of vital activity of an organism, and the violation of protein metabolism in different variants are components of the pathogenesis of all without exception of pathological processes. For a complete presentation of the human protein exchange, based on the concept of nitrogen balance. The normal adult amount of nitrogenous substances withdrawn from the body, is equal to that which he receives from food. In a growing organism, during pregnancy, with the introduction of or excess hormone production anabolic action, when feeding after exhausting diseases of nitrogen excreted less than comes, i.e., anabolic processes prevail over catabolic (positive nitrogen balance). Negative nitrogen balance sheet takes place at the loss of proteins or large consumption of their organism. This may be through fasting, loss of proteins via the kidney (proteinuria), skin (burns), the colon (diarrhea), tireotoxicose, the infectious fever.

Violation of protein metabolism are possible at all stages, starting with suction and ending with deducing from an organism of the end products of metabolism. In such a sequence of these violations will be considered below.

I. Violations of the absorption and synthesis of proteins
As in the organism practically no depo proteins, and the source of amino acids for their synthesis are used in the main components of food, then, of course, in violation of digestion and absorption of proteins develops nutritional protein deficiency. It is observed in case of inflammatory and degenerative changes in the various departments of the intestines, involving violation of their secretory and motor functions, with fasting, poorly balanced amino acid composition of food.

However, for the normal synthesis of proteins must be not only a sufficient number of amino acids, but also correct and active functioning of the system of the synthesis and coding of its genetic structures. Violation of the products of protein can be acquired or hereditary. It is expressed in the change of the number of synthesized molecules or the appearance of molecules with different structure.

Increase or decrease in the number of synthesized protein is often associated with a change in the regulatory influences from a number of hormones, nerves and the immune system. In addition to the breach of proteo synthesis can cause condensation of chromatin in a variety of pathological processes in the cells, fixed speed of cheating messenger RNA in violation of the functioning of the gene regulator or operator (in tumor cells), as well as defects in the structure of ribosomes, arising, for example, under the influence of streptomycin.

The synthesis of proteins with different structure is usually the result of errors in the genome. This may be a violation of the amino acid composition of the protein molecule (for example, a molecule of hemoglobin in sickle cell anemia), shortening of the molecules of transcription (when the information from the DNA-matrix is only to a defect in it), as well as the synthesis of abnormally long proteins, if the mutation occurred in a "stop signal" gene and termination codon disappeared. An example of this is the emergence of a long alpha-globin chains. violation of protein metabolism -
Proteins are the most important biological substances of living organisms. They serve as the plastic material, of which are built cells, tissues and organs of the human body. Proteins are the basis of hormones, enzymes, antibodies and other entities that perform complex functions in human life (digestion, growth, reproduction, immune, etc.), promote normal exchange in the body of vitamins and mineral salts. Proteins involved in the formation of energy, especially in the period of the big energy costs, or when there is not enough in the diet of carbohydrates and fats. The energy value of 1 g of protein equals 4 calories (16,7 Kj).
With the lack of protein in the body there are serious violations of growth and development of children, changes in the liver adults, the activity of the glands of internal secretion, blood composition, the weakening of mental activity, reduced efficiency and resistance to infectious diseases.

When no disease occurs violation of protein metabolism:



Since proteins occupy a Central position in the implementation of the processes of vital activity of an organism, and the violation of protein metabolism in different variants are components of the pathogenesis of all without exception of pathological processes. For a complete presentation of the human protein exchange, based on the concept of nitrogen balance. The normal adult amount of nitrogenous substances withdrawn from the body, is equal to that which he receives from food. In a growing organism, during pregnancy, with the introduction of or excess hormone production anabolic action, when fattening after exhausting diseases of nitrogen excreted less than comes, i.e., anabolic processes prevail over catabolic (positive nitrogen balance). Negative nitrogen balance sheet takes place at the loss of proteins or large consumption of their organism. This may be through fasting, loss of proteins via the kidney (proteinuria), skin (burns), the colon (diarrhea), tireotoxicose, the infectious fever.

Violation of protein metabolism are possible at all stages, starting with suction and ending with deducing from an organism of the end products of metabolism. In such a sequence of these violations will be considered below.

I. Violations of the absorption and synthesis of proteins
As in the organism practically no depo proteins, and the source of amino acids for their synthesis are used in the main components of food, then, of course, in violation of digestion and absorption of proteins develops nutritional protein deficiency. It is observed in case of inflammatory and degenerative changes in the various departments of the intestines, involving violation of their secretory and motor functions, with fasting, poorly balanced amino acid composition of food.

However, for the normal synthesis of proteins must be not only a sufficient number of amino acids, but also correct and active functioning of the system of the synthesis and coding of its genetic structures. Violation of the products of protein can be acquired or hereditary. It is expressed in the change of the number of synthesized molecules or the appearance of molecules with different structure.

Increase or decrease in the number of synthesized protein is often associated with a change in the regulatory influences from a number of hormones, nerves and the immune system. In addition to the breach of proteo synthesis can cause condensation of chromatin in a variety of pathological processes in the cells, fixed speed of cheating messenger RNA in violation of the functioning of the gene regulator or operator (in tumor cells), as well as defects in the structure of ribosomes, arising, for example, under the influence of streptomycin.

The synthesis of proteins with different structure is usually the result of errors in the genome. This may be a violation of the amino acid composition of the protein molecule (for example, a molecule of hemoglobin in sickle cell anemia), shortening of the molecules of transcription (when the information from the DNA-matrix is only to a defect in it), as well as the synthesis of abnormally long proteins, if the mutation occurred in a "stop signal" gene and termination codon disappeared. An example of this is the emergence of a long alpha-globin chains. Production of proteins with different structure may also be a consequence of a breach of one of the links protein synthesis system - machine translation or posttranslational modification of molecules. With the increase in the frequency of translation errors in the process of life associated ageing of the organism.

II. Exchange of amino acids

Violation of transamination and oxidative deamination. Processes transamination and deamination are of universal importance for all living organisms and all amino acids: transamination leads to the formation of amino acids, dezaminirovanie - to their destruction.

The essence of the reaction transamination is the reversible transfer of amino group of amino acids on the a-keto acid without intermediate education of free ammonia. Reaction catalyzed specific enzymes: aminotransferase or transaminases, co-factors which are phosphorylated forms of pyridoxine (pyridoxal and pyrido aminofosfat).

Violations of the reaction transamination can occur for several reasons: it is first of all pyridoxine (pregnancy, the suppression of sulfanilamidnami drugs intestinal flora, partly synthesizing vitamin, the inhibition of the synthesis of pyridoxal during treatment phthivazide). Decrease in the activity of transaminases is also the restriction of protein synthesis (starvation, severe liver disease). If in the individual organs occurs necrosis (myocardial infarction or pulmonary, pancreatitis, hepatitis, etc.), as a result of the destruction of the fabric transaminase enter the blood and increase their activity in the blood at the given pathology is one of the diagnostic tests. To change the speed of transamination a significant role belongs to the violation of the ratio between the substrates reactions, as well as the hormones, particularly glucocorticoids and hormone of the thyroid gland, who renders stimulating influence on this process.

The oppression of oxidative deamination, leading to the accumulation of unused amino acids, may increase the concentration of amino acids in the blood - hyperaminoacidemia. The consequence of this is increased excretion of amino acids kidneys (acidaminuria) and the change in the correlation of individual amino acids in the blood, creating unfavourable conditions for the synthesis of protein structures. Violation of the deamination occurs when the lack of components, directly or indirectly participating in this reaction (lack of pyridoxine, Riboflavin, nicotinic acid; hypoxia; protein-energy malnutrition while fasting).

Violations of the decarboxylation. Being very important, although not universal, the direction of protein metabolism, decarboxylation of proceeds with the formation of CO2 and biogenic amines. Decarboxylation are only some of the amino acids: histidine - with the formation of histamine, tyrosine - tyramine, 1-glutamic acid - γ-aminobutyric acid, 5-hydroxytryptophan - serotonin, tyrosine derivatives (3,4-l-DOPA) and cystine (1-cysteine acid), 3,4-dioxide phenylethylamine (dopamine) and taurine.

Biogenic amines, as it is known, possess particular biological activity and an increase in their number can cause a number of pathological phenomena in the body. The reason for this increase may be not only the strengthening of decarboxylation of the corresponding amino acids, but the oppression of oxidation of amines and violation of their binding proteins. So, for example, under hypoxic conditions, ischemia and destruction of tissue injuries, irradiation, etc.) weakened the oxidation processes, which contributes to the strengthening of the decarboxylation. The emergence of a large number of biogenic amines in the tissues (especially histamine and serotonin) can cause significant violation of local blood circulation, increase of permeability of vessels and damage to the nervous apparatus.

Hereditary metabolic disorders of some amino acids. The passage of amino acids through certain metabolic pathway is determined by the presence and activity of the respective enzymes. Hereditary violation of the synthesis of enzymes leads to the fact that the corresponding amino acid is not included in metabolism, and accumulates in the body and appears in biological environments: urine, feces, sweat, cerebrospinal fluid. The clinical picture of this disease is determined, firstly, the emergence of too high a number of substances, which should be metabolized with the participation of a blocked the enzyme, and secondly, the deficit of the substance, which was to be formed.

Exchange of phenylalanine. Phenylalanine in the norm of the irreversibly is oxidized in the tyrosine. If the liver is violated synthesis of the enzyme phenylalanine, the oxidation of phenylalanine is on the way of education phenyl pyruvic and phenyl lactic acids - develops phenylketonuria. However, this path has low bandwidth and therefore phenylalanine accumulates in large amounts in the blood, tissues and spinal fluid, that in the first months of life leads to a heavy defeat of the Central nervous system and neglected form of dementia. Due to the lack of synthesis of tyrosine decreases the formation of melanin, which leads to the brightening skin and hair. In addition, with the increased development of phenyl pyruvic acid inhibited the activity of the enzyme (dopamine hydroxylase), necessary for the formation of catecholamines (epinephrine and norepinephrine). Therefore, the severity of hereditary diseases is determined by the complex of all these violations.

Install the disease you can with the help of the following tests: when adding a fresh urine a few drops of 5% solution trichloroacetic iron appears olive-green color. Patients die in childhood, if not carried out special treatment, which is in a constant, but a cautious (control of the amino acid composition of the blood) the restriction of the proceeds of phenylalanine with food.

Exchange of tyrosine. Exchange of tyrosine is carried out in several ways. When there is insufficient transformation formed from tyrosine parahydroxy phenyl pyruvic acid in homogentisic the first, as well as tyrosine excreted in the urine. This violation is called tyrosinosis. If the delay oxidation tyrosine is happening at the moment of conversion homogentisic acid in maleinos acetoacetic, develops homogentisuria. The enzyme, oxidizing homogentisic acid oxidase (homogentisic acid), is formed in the liver. It is normally so quickly break it hydroquinone ring that acid does not have time to" appear in the blood, and if it appears, then quickly excreted by the kidneys. For inherited defect of this enzyme homogentisic acid in large quantities is found in the blood and urine. Urine and standing in the air, and when you add to it alkali becomes black. This is due to the oxidation of homogentisic acid oxygen in the air, and education in it alkapona ("exciting alkali"). homogentisic acid from the blood penetrates into the tissue, cartilage, tendons, ligaments, the inner layer of the wall of the aorta, so that there are dark spots in the area of the ears, nose, cheeks, sclera. Sometimes develop severe changes in the joints.

Tyrosine, in addition, is the initial product for the formation of a colouring substance of the skin and hair melanin. If the transformation of tyrosine in the melanin reduced because of hereditary deficiency tyrosinase), there is a albinism.
Finally, tyrosine is a precursor of thyroxine. When there is insufficient synthesis of the enzyme that catalyzes the process of iodization tyrosine free iodine, violated the hormones education thyroid gland.

Exchange of tryptophan. The main route of metabolism of tryptophan leads to the synthesis of the amide of nicotine acid, which plays a very important role in the organism vital activity, as prosthetic group a number of oxidative enzymes - nicotinamide adenine chinook-leotida (ABOVE) and its restored form nicotinamide adenine (NADP). Therefore, when insufficiency of nicotine acid and its amide violated many metabolic reactions, and when the deficit of these substances is developing pellagra.
Disorders of the metabolism of tryptophan may occur also in the change of the quantity generated from him serotonin.

III. Violations of the final stages of protein metabolism
Pathophysiology final stages of protein metabolism includes the pathology of the processes of the formation of nitrogen products (urea, ammonia, uric acid) and remove them from the body. The main indicator of the violations of the formation and emission of urea and other nitrogenous products exchange is to change the content and composition of the residual (albuminous) nitrogen in the blood (norm - 20 - 30 mg%). Rest nitrogen by 50% consists of urea nitrogen, about 25% of it falls on the share of amino acids, the rest - to other nitrogen products. Non-carbamide part of it has received the name residual nitrogen. An increase of residual nitrogen in the blood - giperazotemia - may be the result of violations of education of urea in the liver (production, or liver, giperazotemia) and excretory functions of the kidneys (retention, or kidney, giperazotemia).

Violations of education of urea are observed in a number of diseases (dystrophic changes in the liver, hypoxia), and may also be caused by hereditary defect. Hereditary violations mochevinoobrazovaniya occur when there is insufficient synthesis of arginine-succinate lyase (argininosuktsinat), karbamoilfosfatsintetazy and ornithine carbamoyl transferase (ammoniemiya) and argininosuccinate-synthetase (citrullinemia).

The most common result of the synthesis of urea is the accumulation of ammonia in the blood. The number of it can grow in sharply expressed violation of excretory functions of the kidneys. The toxic effect of ammonia was primarily due to his influence on the Central nervous system. It can be direct and indirect. The latter consists in forcing the neutralization of ammonia due to the binding of his glutamic acid. Off due to this glutamic acid from the exchange manifests itself acceleration transamination amino acids and-ketoglutaric acid, which thus diverted from participation in the cycle of the tricarboxylic acid (Krebs cycle). Sedation of the Krebs cycle leads to delays in the disposal of acetyl-COA, which, turning into ketone bodies, contributes to the development of comatose state.

Violations of education and excretion of uric acid. Uric acid is the end product of the exchange of purine bases, included in the structure of nucleic acids. Violations of education and excretion of uric acid can be observed in diseases of the kidneys, with leucosis. However, the most pronounced of these violations occur in case of gout.

Gout was known even in the ancient world and described by Hippocrates. The study of disease began in 1860., when Garrod, himself suffering from gout, gave her the classic description and found in the blood of patients with an increased content of uric acid (hyperuricemia). To gout there is a predisposition in the form of a predominantly inherited increase the level of uric acid in the blood and, possibly, changes factors supporting uric acid in the dissolved state. Risk factors of occurrence of gout may be the excessive intake of purines in the body (eating large quantities of meat, especially with wine and beer), excessive intake of molybdenum, which is included in the xantinoxydasy, bringing xantin in gipoksantin, which then turns into uric acid; floor (often suffer from male, old age, which is characterized by the age giperuriquemia.

Mechanism of increasing the level of uric acid in the blood of patients is not clear. A specific role in this play as a violation of separation of mochekislah connections kidneys, and the increased education of their glycerin and other predecessors.

Hyperuricemia may be accompanied by the deposition of salts of uric acid in the joints and cartilage, where due to poor blood supply, there is always a tendency to acidification environment that promotes the deposition of salts in sediment (especially the defect factors supporting them in the dissolved state). Deposition of salts causes acute gouty inflammation, accompanied by pain, fever and allergic manifestations and results in the formation of gouty nodes and deformation of the joints.

IV. Violations of the protein composition of the blood

Changes in quantitative and qualitative ratio of blood proteins are observed almost in all pathological conditions, which affect the organism as a whole, as well as in congenital anomalies of the synthesis of proteins. Violation of the content of blood plasma proteins can be expressed change of the total number of proteins (hypoproteinemia, hyperproteinaemia) or the ratio between the individual protein fractions (dysproteinemia) in normal overall content of proteins.

Hypoproteinemia arises mainly due to a reduction in the number of albumins and can be purchased (through fasting, liver diseases, infringement of the absorption of proteins) and hereditary. To gipoproteinemii can also cause the output of the proteins from the bloodstream (loss of blood, plasma loss, exudation, transudation) and loss of protein in the urine (proteinuria).

Hyperproteinaemia more often is relative (blood clots). Absolute hyperproteinaemia is usually associated with hyperglobulinemia, as a rule, with the increase in the level of in-globulins (as compensatory reaction with low content of albumin in the blood, increasing the synthesis of antibodies).

Dysproteinemia have acquired, and hereditary character. Conditionally they can be divided on dis-globulinemia, dis-gammaglobulinemia and dis-immune-globulinemii. At the edge of the protein composition of the blood is simply a reflection of the General restructuring of the immune system, including both cellular reaction.

Examples of the most common dysproteinemia may be an increase in the content of α2-globulin, a decrease α - and β-lipoproteins and violations of the liver, change the number and structure of the gene. The latter is of great practical importance.

Changes γ-globulins may be quantitative or qualitative. Quantitatively modified γ-globulin called paraprotein. They relate to the immunoglobulins and are usually the products of individual clones of antibody-producing cells. An increase in the number of blood is called monoclonal hypergammaglobulinemia and is usually observed in the proliferation of relevant clones, most often caused by the neoplastic nature of the pathological process (a disease mielomnaya, macroglobulinemia waldenstrom). Kind of paraproteins are also cryoglobulins - pathological proteins with the peculiarities of immunoglobulins, which precipitated when cooled.



Which doctor should I contact if there is a violation of protein metabolism

  • Therapeutist
  • Family doctor
  • Dietician


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