FAQ Amino Acids

The preparation of amino acids mainly includes protein hydrolysis, organic synthesis and fermentation methods.

D, L refers to the configuration of amino acids. According to the difference of optical rotation, it can be divided into L-configuration and D-configuration by the calculation (L and D are Latin prefixes, D is dextrorotatory, L is levorotatory). With the exception of glycine, other natural amino acids adopt the L configuration, glycine has no optical activity.

The DL configuration is also a meso amino acid; because there are both D and L configuration carbon atoms. Generally speaking, it is only for a carbon, so there is generally wIthout such DL configuration argument.

Protected amino acids refers to amino acid derivatives whose functional groups react with other groups to block the activity of amino acid functional groups, and all can be called protected amino acids. Including a amino and carboxyl groups, as well as side chain functional groups.

Generally there are tert-butyl, methyl, ethyl, benzyl, allyl, pentafluoro with phenyl, p-methoxybenzyl, etc.

Generally, there are tert-butoxycarbonyl, fluorenylmethyloxycarbonyl, allyloxycarbonyl, trifluoroethoxycarbonyl, benzyloxycarbonyl, ethoxycarbonyl, p-toluenesulfonyl, phthaloyl, and the like.

20 common amino acids can be divided into several categories according to their side chains: aliphatic amino acids (Ala, Gly, Val, Leu, Ile,), aromatic amino acids (Phe, Tyr, Trp, His), amide or carboxyl side chain amino acids ( Asp, Glu, Asn, Gln), basic side chain amino acids (Lys, Arg), sulfur-containing amino acids (Cys, Met), alcohol-containing amino acids (Ser, Thr), imino acid (Pro).

The protection of amino acids in the chemical synthesis of peptides is very important and directly determines the key to the success of the synthesis. Because many of the common 20 amino acids have active side chains and need to be protected, it is generally required that these protecting groups are stable during the synthesis process, without side reactions, and can be completely and quantitatively removed after the synthesis.

The amino acids that need to be protected in the synthesis include: Cys, Asp, Glu, His, Lys, Asn, Gln, Arg, Ser, Thr, Trp, Tyr.

The groups that need to be protected: hydroxyl, carboxyl, sulfhydryl, amino, amide, guanidino, indole, imidazole, etc. Trp can also be left unprotected, because indole is relatively stable in nature. Of course, under special circumstances, some amino acids may not be protected, such as Asn, Gln, Thr, Tyr.

There are three methods: the first one is the trifluoroacetic acid method, which is more commonly used, the second is the concentrated hydrochloric acid method, and the third is the silica gel catalytic method.

There are 20 kinds of basic amino acids, among which 8 kinds of amino acids, lysine, threonine, leucine, isoleucine, valine, methionine, tryptophan, and phenylalanine, cannot be produced by the human body. We call it essential amino acids, which need to be provided by food.

The role of 8 essential amino acids

Leucine

Features:

• Promote sleep
• Reduce sensitivity to pain
• Relieve migraines•Relieve anxiety and tension
• Relieve the symptoms of chemical reaction disorders in the human body caused by alcohol and help control alcoholism

Reference foods: milk, fish, bananas, peanuts and all foods rich in protein

Lysine

Features:

• It can reduce or prevent the occurrence of herpes simplex infections (herpes fever and herpes labialis)
• Able to concentrate attention
• Enables fatty acids for energy production to be used normally
• Helps eliminate certain infertility

Reference food: fish, soy products, skimmed milk, almonds, peanuts, pumpkin seeds and sesame seeds

Phenylalanine

Features:

• Reduce hunger
• Improve libido
• Improve memory and increase the agility of thinking
• Eliminate depression

Reference food: bread, soy products, skimmed milk, almonds, peanuts, pumpkin seeds and sesame seeds

Isoleucine, Valine

Features:

• Necessary for hemoglobin formation
• Regulate sugar and energy levels to help improve physical fitness
• Help repair muscle tissue
• Speed up wound healing
• Treat liver failure
• Raise blood sugar levels and increase growth hormone production

Reference food: eggs, soybeans, rye, whole wheat, brown rice, fish and dairy products

Threonine

Features:

• It is an indispensable amino acid that helps protein to be absorbed and utilized by the body
• Prevent the accumulation of fat in the liver
• Promote the production of antibodies and strengthen the immune system

Reference food: meat, etc.

Methionine

Features:

• Help break down fat, prevent fatty liver, cardiovascular disease and kidney disease
• Remove harmful substances such as lead and other heavy metals
• Prevent muscle weakness
• Treatment of rheumatic fever and toxemia during pregnancy
• A beneficial antioxidant

Reference food: soybeans, other beans, fish, garlic, meat, onions and yogurt

Tryptophan

Features:

• Helps reduce restlessness
• Promote sleep
• Can control alcoholism

Reference food: brown rice, meat, peanuts, soy protein

α-amino acid can react with ninhydrin to produce blue-purple substance:

This reaction is a unique reaction of α-amino acids. This reaction can be used to identify the existence of α-amino acids, and it is also commonly used for the colorimetric determination of α-amino acids and the color development of chromatographic analysis.

The reactions that α-amino participates in generally include:

1. In the reaction with nitrous acid, the content of amino acids can be calculated by measuring the volume of nitrogen.
2. The reaction with acylating reagents can be used to protect amino groups.
3. Hydrocarbylation reaction can be used to determine the nitrogen-terminal amino acid of the polypeptide chain.
4. The reaction to form schiff base is an intermediate step in the transamination reaction.
5. Deamination reaction is an important intermediate step in the decomposition reaction of amino acids.

Definition of amino acid: A compound containing one or more amino and carboxyl groups at the same time is called an amino acid.

Classification of amino acids:

1. According to the positions of amino and carboxyl groups, there are α amino acids and β amino acids;
2. According to whether they participate in protein synthesis, amino acids can be divided into protein amino acids (only more than 20 kinds) and non-protein amino acids (the more common ones are , Ornithine, Citrulline, GABA, etc.);
3. According to whether the human body can synthesize it, amino acids can be divided into essential amino acids and non-essential amino acids. There are 8 kinds of amino acids essential to the human body: leu, ile, lys, phe, met, thr, trp, and val.

The sources and fabrication methods of amino acids mainly include protein hydrolysis, microbial fermentation, enzyme engineering technology and chemical synthesis. The amino acids produced by chemical synthesis are generally of DL configuration and need to be resolved to obtain the corresponding D or L configuration. The asymmetric synthesis of amino acids has developed rapidly in recent years.

1. Methyl or ethyl ester
2. Benzyl ester or substituted benzyl ester
3. tert-butyl ester
4. Allyl ester
5. Hosu ester, onp ester and opfp ester
6. Trimethyl silicone or triethyl silicone
7. Amide or hydrazide

1. boc or bpoc
2. fmoc
3. cbz or 2-clz
4. trt
5. pht
6. tfa
7. nps
8. ac or for
9. adoc

The pseudoproline dipeptide of formula I can be used as a reversible protecting group for Ser, Thr and Cys and has been proven to be a universal tool in the field of peptide chemistry to overcome certain inherent problems. The presence of ψPro in the peptide sequence caused the destruction of the ?-fold structure which is considered to be the source of intermolecular aggregation. The increase in solvation and coupling kinetics caused in peptide assembly such as Fmoc solid phase peptide synthesis makes chain extension easier, especially for peptides containing "difficult sequences".