1. Total enzymatic synthesis of cholecystokinin CCK-5.
- Author
-
Xiang H, Xiang GY, Lu ZM, Guo L, and Eckstein H
- Subjects
- Acetates chemistry, Bacillus metabolism, Catalysis, Chromatography, High Pressure Liquid, Esters chemistry, Glycine chemistry, Hydrolysis, Papain chemistry, Penicillin Amidase chemistry, Penicillin G chemistry, Pentagastrin chemistry, Peptides chemistry, Solvents chemistry, Thermolysin chemistry, Enzymes, Immobilized chemistry, Peptide Fragments chemical synthesis, Peptide Fragments chemistry, Sincalide chemical synthesis, Sincalide chemistry
- Abstract
This paper describes the enzymatic synthesis of the C-terminal fragment H-Gly-Trp-Met-Asp-Phe-NH2 of cholecystokinin. Immobilized enzymes were used for the formation of all peptide bonds except thermolysin. Beginning the synthesis with phenylacetyl (PhAc) glycine carboxamidomethyl ester (OCam) and H-Trp-OMe by using immobilized papain as biocatalyst in buffered ethyl acetate, the dipeptide methyl ester was then coupled directly with Met-OEt.HCl by alpha-chymotrypsin/Celite 545 in a solvent free system. For the 3+2 coupling PhAc-Gly-Trp-Met-OEt had to be converted into its OCam ester. The other fragment H-Asp(OMe)-Phe-NH2 resulted from the coupling of Cbo-Asp(OMe)-OH with H-Phe-NH2.HCl and thermolysin as catalyst, followed by catalytic hydrogenation. Finally PhAc-Gly-Trp-Met-Asp-Phe-NH2 was obtained in a smooth reaction from PhAc-Gly-Trp-Met-OCam and H-Asp(OMe)-Phe-NH2 with alpha-chymotrypsin/Celite 545 in acetonitrile, followed by basic hydrolysis of the beta-methyl ester. The PhAc-group is removed with penicillin G amidase and CCK-5 is obtained in an overall isolated yield of 19.6%.
- Published
- 2004
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