Edit this paragraph to define amino acids: a generic term for a class of organic compounds containing amino groups and carboxyl groups. Protein is the basic unit of biological macromolecules, and it is the basic substance that constitutes protein for animal nutrition. It is an organic compound, which contains a basic amino group and an acidic carboxyl group. The amino group is usually attached to α carbon. General structural formula of amino acids: The amino acids that make up protein are all organic compounds with carboxyl and amino groups, and the amino groups are attached to the carbon atoms on the carboxyl groups. At present, there are no amino acids in protein that are not linked to the same carbon atom. Edit this paragraph to classify more than 300 kinds of natural amino acids, including about 22 kinds of amino acids needed by human body, which are divided into non-essential amino acids and essential amino acids (the human body cannot synthesize them by itself). There are also classifications of acidic, alkaline, neutral and heterocyclic compounds, which are classified by chemical properties. 1. Essential amino acids: It means that the human body (or other vertebrates) can't synthesize them or the speed of synthesis can't meet the needs of the body, so they must be supplied by food protein. These amino acids are called essential amino acids. * * * has eight functions: ① lysine: it promotes brain development, is a component of liver and gallbladder, promotes fat metabolism, regulates pineal gland, breast, corpus luteum and ovary, and prevents cell degeneration; ② Tryptophan: promoting the production of gastric juice and pancreatic juice; (3) phenylalanine: involved in eliminating the loss of kidney and bladder function; ④ Methionine (also called methionine); Participate in the composition of hemoglobin, tissue and serum, and promote spleen, pancreas and lymph; ⑤ Threonine: It can transform some amino acids to achieve balance; ⑥ Isoleucine: involved in the regulation and metabolism of thymus, spleen and submandibular gland; The general command of submandibular gland acts on thyroid gland and gonad; ⑦ Leucine: plays the role of balancing isoleucine; Valine: It acts on corpus luteum, breast and ovary. The memory formula of eight essential amino acids-"Borrow one or two egg color books" is homophonic: Borrow (valine), I (isoleucine), II (leucine), Ben (phenylalanine), egg (methionine), color (tryptophan), Ben (threonine) and lysine. Its physical and chemical characteristics are roughly: 65438. The melting point is above 230℃, and most of them have no exact melting point, which explains when the released CO2 melts. Soluble in strong acid and alkali solution, except cystine, tyrosine and diiodothyroxine, which are all soluble in water; Except proline and hydroxyproline, it is almost insoluble in ethanol and ether. 2) Alkaline [diaminomonocarboxylic acid, such as lysine]; ; Acidity [monoamine dicarboxylic acid such as glutamic acid]; ; Neutral [monoamine monocarboxylic acid, such as alanine)] three types. Most amino acids are acidic or alkaline to varying degrees, and rarely neutral. So it can combine with acid and alkali to form salt. 3) Because the carbon atoms are asymmetric, they are optically active. At the same time, due to the different spatial layout, there are two configurations: D type and L type. The amino acids that make up protein belong to L-type. In biochemical research, amino acids usually refer to α-amino acids, because all amino acids were hydrolyzed from protein (now they are mostly synthesized) and all amino acids obtained from protein hydrolysis are α-amino acids. As for β, γ, δ and other amino acids ... ω, they are of little use in biochemical research, and are mostly used in organic synthesis, petrochemical industry, medical treatment and so on. There are many kinds of amino acids and their derivatives, most of which are relatively stable and should be stored in a dry place away from light. 2. Non-essential amino acids: refers to amino acids that people (or other vertebrates) can synthesize from simple precursors and do not need to obtain from food. Such as glycine, alanine and other amino acids. One-letter abbreviation and list of properties of amino acids: Chinese translation of abbreviation full name branched chain molecular weight isoelectric point dissociation constant (carboxyl group) dissociation constant (amino group) pKr(R) G Gly glycine glycine hydrophilicity 75.07 6.06 2.35 9.78 A Ala alanine alanine hydrophilicity 89.096.1kloc-0/ 2.35 9.87V Valine Hydrophilicity117.654330 2.39 9.74L Leucine Leucine Hydrophilicity 1. 1 76.012.33 9.74IILE Leucine Isoleucine Hydrophilicity1./. .766 6.05 2.329.76f. Phe phenylalanine phenylalanine hydrophobicity165.19 5.49 2.20 9.36555438+055.167.601.809.336.04. Kloc-0/32.125.412.148.72e Glu Glu Glu Glu Glu Glu Glu Acidity 65438+047.133.6543846.15.652./. 3m methionine methionine is hydrophobic149.215.742.139.28r arginine is alkaline 174.20 10. 76 1.82 8.99 12.48 s serine hydrophilicity105.09 5.682.199.21t threonine hydrophilicity1/9. 9 9. 10 C Cys cysteine cysteine hydrophilicity121.165.051.9210.708.37p proline proline hydrophobicity1/kloc. 438+0.95 10.64 Edit this detection 1, color of ninhydrin reaction reaction reagent Remarks: ninhydrin (heated in weak acid environment) blue (proline and hydroxyproline are yellow) (detection of α-amino) 2, Sakaguchi reaction (α-naphthol+alkaline sodium hypobromide red) 3. Miron reaction (HgNO3+HNO3+ hot red) 4. Folin-Ciocalteau reaction (phosphotungstic acid-phosphocholic acid blue) 5. Yellow protein reacts with concentrated nitric acid to cook yellow (tested by benzene ring tyrosine, phenylalanine and tryptophan have this reaction) 6. Hopkin-Cole reaction (glyoxylic acid reaction) Glyoxylic acid+concentrated H2SO4 acetaldehyde produces a purplish red color ring at the contact surface with concentrated H2SO4 (indolyl tryptophan has this reaction after testing) 7. Ehrlich reaction p-dimethylaminobenzaldehyde+concentrated hydrochloric acid blue (the experiment shows that indolyl tryptophan has this reaction) 8. Nitropril salt test Na2(NO)Fe(CN)2*2H2O+ dilute ammonia red (the test shows that mercaptocysteine has this reaction) 9. Sullivan reaction 1, 2- naphthoquinone, 4- sodium sulfonate +Na2SO3 red (tested by mercaptocysteine) 10, Flynn reaction 1, 2- naphthoquinone and 4- sodium sulfonate show deep red (tested by α-amino acid) peptide bond in alkaline solution: carboxyl group of one amino acid and another amino acid. Peptide: A polymer in which two or more amino groups are linked by peptide bonds. Amino acids are compounds linked by peptide bonds, and the products of incomplete hydrolysis of protein are also peptides. Peptides are called dipeptides, tripeptides, tetrapeptides and so on. Depending on the number of amino acids, they are composed of, for example, 2, 3 and 4 amino acids. Generally, oligopeptides are composed of less than 65,438+00 amino acids, and polypeptides are composed of more than 65,438+00 amino acids, all of which are simply called peptides. Amino acids in peptide chains are not free amino acid molecules, because amino groups and carboxyl groups combine to form peptide bonds, so amino acids in peptides and protein molecules are called amino acid residues. Polypeptides include open-chain peptides and cyclic peptides. In human body, it is mainly open-chain peptide. Open-chain peptides have a free amino terminal and a free carboxyl terminal, which retain free α -amino and α -carboxyl groups respectively, so they are also called N-terminal (amino terminal) and C-terminal (carboxyl terminal) of polypeptide chains. When writing, the N-terminal is usually written on the left side of the molecule, which is represented by (H), so that the amino acid residues in the polypeptide molecule are numbered in turn, while the C-terminal of the peptide chain is written on the right side of the molecule. At present, the amino acid compositions and sequences of about 200,000 kinds of peptides and polypeptides in protein molecules have been determined, many of which are closely related to medicine and have important physiological or pharmacological functions respectively. Polypeptides are widely distributed in the body and have important physiological functions. Red blood cells are rich in glutathione, which can protect the structure of cell membrane and make the enzyme protein in cells active in reduction. Among various peptides, glutathione has a special structure. Glutamate in the molecule is dehydrated and condensed with α -amino group of cysteine to form peptide bond, and reversible redox reaction can occur in cells, so there are two kinds of glutathione: reduced glutathione and oxidized glutathione. In recent years, some polypeptide molecules with strong biological activity have been continuously discovered and identified, most of which have important physiological or pharmacological functions. For example, some "brain peptides" are closely related to the body's learning and memory, sleep, appetite and behavior, which increases people's understanding of the importance of peptides, and peptides have become one of the remarkable research fields in biochemistry. The difference between polypeptide and protein is that, on the one hand, the number of amino acid residues in polypeptide is less than that in protein, generally less than 50, while protein is mostly composed of more than 100 amino acid residues, but there is no strict dividing line between them in terms of number. Apart from molecular weight, it is still believed that peptides generally have no strict and relatively stable spatial structure, that is, their spatial structure is relatively easy to change and plasticity, while protein molecules have relatively strict and stable spatial structure, which is also the reason why protein plays an important role. But in some books, insulin is not called polypeptide strictly because of its small molecular weight. However, both polypeptide and protein are polycondensates of amino acids, and polypeptide is also the product of incomplete hydrolysis of protein. Patent collection of amino acid preparation 1, amino acid nano-selenium and its preparation method 2, polyester with active drugs and amino acids in its main chain and its preparation method 3, composite amino acid capsule and its preparation method 4, method for preparing D- amino acid by hydrolyzing D-N- carbamoyl amino acid with ion exchange resin 5, method for preparing D- amino acid oxidase 6, method for preparing a series of D-a- amino acids with Onion JS-02 of Dermatidaceae 7, Preparation method of amino acid salt of 3- hydroxy -3- methylbutyric acid (HMB) 8. Cyclone and its preparation method and application in the synthesis of amino acids 9. Amino acid human hair nutritional food or pharmaceutical additive and its preparation method 10, preparation method of amino acid foliar fertilizer 165433. Preparation method of amino acid-medical stone compound trace element fertilizer 12, preparation method of enantiomerically enriched β -amino acid by enzymatic method 13, preparation method of enantiomerically enriched β -amino acid by enzymatic method 14, aromatic amino acid derivatives and their preparation methods and medical uses 15, l- amino acid acyl- Amines and their derivatives and their preparation methods 16, stable solid dosage forms of amino acids and their preparation methods 19, preparation method of zinc amino acid and its application 20, preparation method of optically active amino acids by thermal hydrolysis of nitrogen-carbamoyl amino acids. At present, it is considered that the absorption of amino acids and dipeptides and tripeptides composed of various amino acids is similar to that of monosaccharides, and they are all actively transported and coupled with Na+ transport. When the peptide enters intestinal mucosal epithelial cells, it is hydrolyzed into amino acids by peptidase existing in the cells immediately. Therefore, almost all amino acids are absorbed into venous blood. The functional amino acids in this paragraph are the most basic substances that constitute the protein of organisms and are related to life activities. They are the basic units of protein molecules in organisms and are closely related to the life activities of organisms. It has a special physiological function in antibodies and is one of the indispensable nutrients in organisms. 1. The basic substance that constitutes the human body is the material basis of life. 1. protein, lipids, carbohydrates, inorganic salts, vitamins, water and dietary fiber constitute one of the most basic substances in human body. As the basic unit of protein molecule, amino acid is undoubtedly one of the most basic substances in human body. There are more than 20 kinds of amino acids that make up the human body, namely: tryptophan, methionine, threonine, valine, lysine, histidine, leucine, isoleucine, alanine, phenylalanine, cystine, cysteine, arginine, glycine, serine, tyrosine and 3.5. Diiodotyrosine, glutamic acid, aspartic acid, proline, hydroxyproline, arginine, citrulline, Ukraine. These amino acids exist in nature and can be synthesized in plants, but the human body cannot synthesize them all. Eight of them are not synthesized by human body and must be provided by food, which are called "essential amino acids". These eight essential amino acids are tryptophan, threonine, methionine, valine, lysine, leucine, isoleucine and phenylalanine. Others are "nonessential amino acids". Histidine can be synthesized in human body, but its synthesis speed can not meet the needs of the body, and some people list it as "essential amino acid". Cystine, tyrosine, arginine, serine and glycine are classified as "semi-essential amino acids" because they can be synthesized in vivo, but their synthetic raw materials are all essential amino acids. Cystine can replace 80% ~ 90% of methionine, and tyrosine can replace 70% ~ 75% of phenylalanine to play the role of essential amino acids. For example, according to its metabolic pathway in the body, it can be divided into "ketogenic amino acids" and "glycogenic amino acids"; According to its chemical properties, it can be divided into neutral amino acids, acidic amino acids and basic amino acids, most of which are neutral. 2. The material basis of life metabolism The emergence, existence and extinction of life are all related to protein, as Engels said: "protein is the material basis of life, and life is a form of existence in protein." If the human body lacks protein, its physique will be reduced, its development will be delayed, its resistance will be weakened, anemia will be weak, and edema will be formed in severe cases, even life-threatening. Once protein is lost, life will cease to exist, so some people call protein "the carrier of life". Can be said to be the first element of life. The basic unit of protein is amino acid. If the human body lacks any essential amino acids, it will lead to abnormal physiological function, affect the normal metabolism of antibodies and eventually lead to diseases. Similarly, if the human body lacks some non-essential amino acids, there will also be disorder of antibody metabolism. Arginine and citrulline are very important for the formation of urea. Insufficient intake of cystine will cause insulin decrease and blood sugar increase. For example, the demand for cystine and arginine has greatly increased after trauma. Without it, even if the heat energy is sufficient, protein can't be successfully synthesized. In a word, amino acids can play the following roles in human body through metabolism: ① synthesis of tissue protein; (2) into acid, hormone, antibody, creatine and other ammonia-containing substances; (3) into carbohydrates and fats; ④ Oxidation into carbon dioxide, water and urea to generate energy. Therefore, the existence of amino acids in human body not only provides important raw materials for the synthesis of protein, but also provides a material basis for promoting growth, normal metabolism and maintaining life. If the human body lacks or reduces one of them, the normal life metabolism of the human body will be hindered, and even various diseases or life activities will be terminated. This shows how many amino acids are needed for human life activities. Second, its position and function in food nutrition. In order to survive, human beings must eat food to maintain the normal physiological, biochemical and immune functions of antibodies, as well as life activities such as growth, development and metabolism. The comprehensive process of digestion, absorption and metabolism of food in the body, promoting the growth and development of antibodies, improving intelligence and physique, resisting aging and preventing diseases, and prolonging life is called nutrition. The effective ingredients in food are called nutrients. Protein, lipids, carbohydrates, inorganic salts (that is, minerals, which contain a large number of elements and trace elements), vitamins, water and dietary fiber, which constitute the most basic substances of the human body and are also nutrients needed by the human body. They have their own unique nutritional functions in the body, but they are closely related in the process of metabolism, participating, promoting and regulating life activities together. The body communicates with the outside world through food, keeping the internal environment relatively constant, and completing the unity and balance of the internal and external environment. What role do amino acids play in these nutrients? 1. protein is digested and absorbed by amino acids in the body. Protein, as the first nutrient element in the body, plays an obvious role in food nutrition, but it can't be directly used in the human body, but can be used by turning it into small molecules of amino acids. That is, it is not directly absorbed by the human body in the gastrointestinal tract, but is decomposed into low molecular weight peptides or amino acids by various digestive enzymes in the gastrointestinal tract, and then absorbed in the small intestine and enters the liver along the hepatic portal vein. Some amino acids are decomposed or synthesized into protein in the liver; Another part of amino acids continue to distribute to various tissues and organs with blood, and can freely choose to synthesize various specific tissue proteins. Under normal circumstances, the speed of amino acids entering the blood is almost equal to its output speed, so the content of amino acids in normal people's blood is quite constant. If calculated by amino nitrogen, the content is 4-6 mg per 100 ml of plasma and 6.5-9.6 mg per 100 ml of blood cells. After a full meal in protein, a large number of amino acids were absorbed, and the level of amino acids in blood temporarily increased, and the content returned to normal after 6-7 hours. It shows that amino acid metabolism in the body is in dynamic balance, with blood amino acids as its balance hub, and liver is an important regulator of blood amino acids. Therefore, food protein is digested and decomposed into amino acids and then absorbed by human body, and antibodies use these amino acids to synthesize their own protein. What the human body needs for protein is actually the need for amino acids. 2. Play a role in nitrogen balance When the quality and quantity of protein in daily diet are appropriate, the amount of nitrogen intake is equal to the amount of nitrogen discharged from feces, urine and skin, which is called the total balance of nitrogen. In fact, it is the balance of continuous synthesis and decomposition between protein and amino acids. Normal people's daily intake of protein should be kept within a certain range. When the intake suddenly increases or decreases, the body can still regulate the metabolism of protein and maintain the nitrogen balance. Excessive intake of protein, beyond the body's regulatory capacity, will destroy the balance mechanism. If you don't eat protein at all, the tissue proteins in your body will still decompose and negative nitrogen balance will continue to appear. If measures are not taken to correct it in time, the antibody will eventually die. 3. α -keto acids produced by amino acid catabolism of sugar or fat are metabolized along the metabolic pathways of sugar or fat with different characteristics. α-keto acids can be synthesized into new amino acids, or converted into sugar or fat, or decomposed into CO2 and H2O through cyclic oxidation of tricarboxylic acid, releasing energy. 4. Groups containing one carbon atom are generated during the catabolism of some amino acids in a carbon unit, including methyl, methylene, methylene, methylthio, cresol and iminomethyl. A carbon unit has the following two characteristics: 1. It cannot exist in an organism in a free form; 2. Tetrahydrofolate must be used as a carrier. Amino acids that can produce one carbon unit are serine, tryptophan, histidine and glycine. In addition, methionine can provide "active methyl" (a carbon unit) through S- adenosylmethionine (SAM), so methionine can also generate a carbon unit. The main physiological function of a carbon unit is as the raw material for the synthesis of purine and pyrimidine, and it is the link between amino acids and nucleotides. 5. The chemical essence of enzymes, hormones and some vitamins is protein (amino acid molecular composition), such as amylase, pepsin, cholinesterase, carbonic anhydrase, transaminase, etc. The nitrogen-containing hormone is protein or its derivatives, such as growth hormone, thyroid stimulating hormone, adrenaline, insulin, intestinal juice stimulating hormone, etc. Some vitamins are converted from amino acids or exist in combination with protein. Enzymes, hormones and vitamins play a very important role in regulating physiological functions and catalyzing metabolism. 6. The requirement of essential amino acids for human body is about 20% ~ 37% of that of protein. Three. Application of amino acids in medical treatment: Amino acids are mainly used to prepare compound amino acid infusion in medicine, and also used as therapeutic drugs and synthetic peptide drugs. At present, there are more than 100 kinds of amino acids used as drugs, including 20 kinds of amino acids that constitute protein and more than 100 kinds of amino acids that constitute non-protein. Compound preparation composed of various amino acids plays a very important role in modern intravenous nutrition infusion and "element diet" therapy. It plays an active role in maintaining the nutrition of critically ill patients and saving their lives, and has become one of the indispensable medical varieties in modern medicine. Amino acids such as glutamic acid, arginine, aspartic acid, cystine and levodopa can be used alone to treat some diseases, mainly for treating liver diseases, digestive tract diseases, encephalopathy, cardiovascular diseases and respiratory diseases, as well as improving muscle vitality, pediatric nutrition and detoxification. In addition, amino acid derivatives are also promising in cancer treatment. Fourth, the relationship with aging If the elderly lack protein, there will be more decomposition and slower synthesis. Therefore, generally speaking, the elderly need more protein than young adults, and the demand for methionine and lysine is also higher than young adults. The elderly over 60 years old should consume about 70g of protein every day, and it is required that protein contains all kinds of essential amino acids in proper proportion, so as to provide high-quality protein and prolong life. 5. Foods rich in amino acids include fish, such as cuttlefish, octopus, eel, loach, sea cucumber, cuttlefish, silkworm chrysalis, chicken, frozen tofu and laver. In addition, like beans, peanuts, almonds or bananas contain more amino acids than beef, eggs, soybeans, tremella, viscera of fresh fruits and vegetables, lean meat, fish, milk, yam and lotus root. /CA & gt； * Corn is seriously lacking the function of lysine protein: 1 structure and supporting function. Regardless of cell membrane, nucleus or cytoplasm, protein is the main component that forms these structures. 2 catalysis: almost all chemical reactions in organisms need the catalysis of catalysts, and these catalysts are enzymes. The enzymes found at present are all protein in chemical properties. 3. Regulation: Some hormones in organisms, such as insulin and auxin, are also protein. The interaction of these hormones regulates the normal growth, development and metabolism of organisms. 4. Transport function: Some protein on the cell membrane are specially responsible for the transmembrane transport of certain substances; There are many protein in blood that can transport carbon dioxide and oxygen, such as hemoglobin in red blood cells. 5. Defense: The antibodies in the immune system of higher animals can invade foreign harmful substances. These antibodies are not only the result of immunoglobulin 6: motor function: protein sliding with each other during muscle contraction; Cell division and various cell movements are related to protein. To sum up, eating foods containing more amino acids will not lead to excessive urination.
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