1. Definition:
amino acid: the basic unit of protein, a biologically functional macromolecule, is the basic substance that constitutes the protein needed for animal nutrition. It is an organic compound containing an alkaline amino group and an acidic carboxyl group, and the amino group is generally attached to the α-carbon.
general structural formula of amino acids: amino acids refer to a class of organic compounds containing carboxyl groups and having amino groups under carbon atoms connected to the carboxyl groups.
2. Classification:
There are about 22 kinds of amino acids needed by human body, which are divided into non-essential amino acids and essential amino acids (which must be supplied from food). There are also acidic, alkaline, neutral and heterocyclic classifications, which are classified according to their chemical properties.
1. essential amino acid: It means that human body (or other vertebrates) can't synthesize it or its synthesis speed is far from meeting the needs of the body, so it must be supplied by food protein. These amino acids are called essential amino acids. * * * There are 1 kinds of its functions: < P > (1) Lysine: it promotes brain development, is a component of liver and gallbladder, can promote fat metabolism, regulate pineal gland, breast, corpus luteum and ovary, and prevent cells from returning;
(2) Tryptophane: promoting the production of gastric juice and pancreatic juice;
(3) Phenylalanine: it is involved in eliminating the loss of kidney and bladder function;
(4) methionine; Participate in the composition of hemoglobin, tissue and serum, and have the function of promoting spleen, pancreas and lymph;
(5) Threonine: it has the function of transforming some amino acids to achieve balance;
(6) Isoleucine: involved in the regulation and metabolism of thymus, spleen and submaxillary gland; The general command of submaxillary gland acts on thyroid gland and gonad;
(7) Leucine: it acts to balance isoleucine;
(8) Viline: it acts on corpus luteum, breast and ovary.
(9) Hlstidine: it acts on the regulation of metabolism;
(1) Argnine: promoting wound healing, sperm protein component.
Its physical and chemical characteristics are as follows:
1) They are colorless crystals. The melting point is about 23. Above c, most of them have no exact melting point, and decompose and release CO2； when melting; Can be dissolved in strong acid and alkali solution, except cystine, tyrosine and diiodothyroxine, which are all soluble in water; Except proline and hydroxyproline, they are hardly soluble in ethanol and ether.
2) alkaline [diaminomonocarboxylic acid, such as lysine)]；; Acidity [monoamine dicarboxylic acids such as Glutamic acid)]；; Neutral [monoamine monocarboxylic acid, such as Alanine)] three types. Most amino acids are acidic or alkaline to varying degrees, and few are neutral. Therefore, it can be combined with acid and alkali to form salt.
3) Because of asymmetric carbon atoms, it is optically active. At the same time, due to the different spatial arrangement, there are two configurations: D-type and L-type. The amino acids that make up protein belong to L-type. Because amino acids used to come from protein hydrolysis (now they are mostly synthetic), and the amino acids obtained from protein hydrolysis are all α-amino acids, so amino acids usually refer to α-amino acids in biochemical research. As for the amino acids such as β, γ, δ ... 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 stable in nature, so they should be stored in the dark and dry.
2. nonessential amino acid: refers to the amino acid 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.
Third, detection:
ninhydrin reaction: the reaction of amino acids or peptides with ninhydrin reaction to form purple compounds (which react with proline to form yellow compounds) under heating conditions.
peptide bond: the carboxyl group of one amino acid is condensed with the amino group of another amino acid to remove the amide bond formed by one molecule of water.
peptide: a polymer formed by connecting two or more amino groups through 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, etc. according to their different number of amino acids. Generally, oligopeptide with less than 1 amino acids and polypeptide with more than 1 amino acids are called peptides for short. The amino acids in the peptide chain are not free amino acid molecules, because the amino groups and carboxyl groups are combined in the formation of peptide bonds, so the amino acids in the polypeptide and protein molecules are both called amino acid residue.
peptides 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 group and α-carboxyl group respectively, so they are also called N-terminal (amino terminal) and C-terminal (carboxyl terminal) of polypeptide chain. When writing, N-terminal is generally written on the left side of the molecule and denoted by (H), so that the amino acid residues in the polypeptide molecule are numbered in turn, while C-terminal of peptide chain is written on the right side of the molecule. At present, the amino acid composition and sequence of about 2, kinds of peptides and peptides 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. Glutathione is rich in red blood cells, which has the functions of protecting cell membrane structure and making intracellular enzyme proteins in a reduced and active state. Among all kinds of peptides, glutathione has a special structure. Glutamate in the molecule is dehydrated and condensed with α-amino of cysteine to form peptide bonds, and it can undergo reversible redox reaction 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, and most of them have important physiological functions or pharmacological effects. For example, some "brain peptides" are closely related to learning and memory, sleep, appetite and behavior of the body, which increases people's understanding of the importance of polypeptides, and polypeptides 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 5, while protein is mostly composed of more than 1 amino acid residues, but there is no strict dividing line between them in quantity. Apart from molecular weight, it is still believed that polypeptide generally has no tight and relatively stable spatial structure, that is, its spatial structure is relatively easy to change and plasticity, while protein molecule has a relatively tight and stable spatial structure, which is also the physiological function of protein. However, in some books, insulin is not strictly called polypeptide 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.
primary structure of protein: refers to the sequence of amino acid residues linked with valence of * * * in protein.
Patent Collection for Preparation of Amino Acids
1. Amino acid nano-selenium and its preparation method
2. Polyester containing active drugs and amino acids in the main chain and its preparation method
3. Compound amino acid capsules and their preparation method
4. Method for preparing D- amino acids by hydrolyzing D-N-carbamoyl amino acids with ion exchange resin
5. D-amino acid oxidase. Method for preparing a series of D-a- amino acids by using Derridae Onion JS-2
7, method for preparing amino acid salt of 3-hydroxy-3-methylbutyric acid (HMB
8, cyclic ketone, its preparation and its application in synthesizing amino acids
9, an amino acid human hair nutritional food or pharmaceutical additive and its preparation method
1. Preparation method of amino acid-medical stone compound trace element fertilizer
12, preparation method of enantiomerically enriched β -amino acid by enzyme
13, preparation method of enantiomerically enriched β -amino acid by enzyme
14, aromatic amino acid derivatives, Its preparation method and its medical use
15, L-amino acid acyl-(8-quinolinyl) amine and its derivatives and its preparation method
16, stable amino acid solid dosage forms and their preparation method
17, new amino acid derivatives, their preparation method and pharmaceutical composition containing the compound
18, method for preparing amidocarboxylic acid by reacting amino acid with carboxylic anhydride <