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Relying on profound professional knowledge and professional technical equipment, BOC Sciences can provide customers with amino acid protection and deprotection services. Based on this, we can also provide ready-made or customized free amino acids, protected amino acids and their derivatives.
Amino acids are the source of all life and the basic substance of proteins in living organisms. Two or more amino acids undergo dehydration condensation to form peptide chains, the original fragments of proteins. One or more peptide chains combine in specific ways to form proteins. Peptides are a class of compounds whose molecular structure is between amino acids and proteins. They are composed of a variety of amino acids bonded through peptide bonds in a certain order. The synthesis of peptides is the condensation of amino acids. The difficulty lies in the fact that the active groups of amino acids are easy to react with the reagents that connect the peptides, thus causing the misconnection of amino acids and the occurrence of many side reactions. Therefore, in the synthesis of peptides, the protection of amino acids is very critical, which directly determines the key to the success of the synthesis.
In peptide synthesis, in order to obtain the ideal target peptide, it is first necessary to protect the active groups of amino acids. Choosing an appropriate protecting group is the key to the successful synthesis of target compounds. After the target peptide is synthesized, the protecting group is removed. We provide comprehensive integrated solutions from amino acid protection to amino acid deprotection to solid-phase peptide synthesis. Based on efficient services, we also synthesize high-quality and cheap free amino acids, protected amino acids, peptides and their derivatives.
Amino acid protection can be divided into substituted alkoxycarbonyl protection, acyl protection and alkyl protection. Among them, substituted alkoxycarbonyl protection is the most commonly used means of amino protection. Because the amino acid protected by the alkoxycarbonyl group is not easy to racemize during the peptide grafting process.
| Abbreviation | Structure | Removal condition |
| Trt |  | TFA, HOAc, HCOOH |
| Boc |  | HCl/HOAc, TFA/DCM |
| Fmoc |  | PIP/DMF, NaOH/MeOH |
| Dde |  | H2NNH2/DMF |
| Allyl |  | Pd (Ph3P)4, Morpholine/THF |
Table 1 Common amino protection and deprotection
We usually use esterification reaction to realize the protection of carboxyl group, and sometimes use the form of substituted hydrazide for protection. The deprotection of amino acids after esterification mainly includes three methods. (1) Use alkali to saponify and remove in organic aqueous solution, such as the deprotection of methyl ester and ethyl ester. (2) Use acid to saponify and remove in organic aqueous solution, such as the deprotection of tert-butyl ester and p-methyl chloride benzyl ester. (3) Use other methods to selectively remove, such as the use of hydrogenolysis to achieve deprotection of benzyl esters and substituted benzyl esters.
| Abbreviation | Structure | Removal condition |
| OtBu |  | TFA, HOAc, HCOOH |
| OBzl |  | H2/Pd, HF, TFMSA |
| OMe |  | NaOH/MeOH |
| OAll |  | Pd (Ph3P)4, Morpholine/THF |
| OFm |  | PIP/DMF, DBU/DMF |
Table 2 Common carboxyl protection and deprotection
The active side chains of amino acids mainly include: hydroxyl, mercapto, carboxyl, amino, guanidine, imidazole, amide, indole, thioether, etc. In peptide synthesis, the sulfhydryl group of cysteine and the amino group of lysine must be protected. The carboxyl groups of glutamic acid and aspartic acid must also be protected as carboxyl components.
| Abbreviation | Structure | Removal condition |
| Trt |  | TFA, HCl/HOAc, I2/MeOH |
| Acm |  | I2/MeOH, Hg2+ |
| Mob |  | HF, TFMSA, Hg2+ |
Table 3 Common side chain thiol protection and deprotection
