title: Enzymatic synthesis of a CCK-8 tripeptide fragment in organic media.
abstract: The enzymatic synthesis of the tripeptide derivative Z-Gly-Trp-Met-OEt is reported. This tripeptide is a fragment of the cholecystokinin C-terminal octapeptide CCK-8. Studies on the alpha-chymotrypsin catalyzed coupling reaction between Z-Gly-Trp-R(1) and Met-R(2) have focused on low water content media, using deposited enzyme on inert supports such as Celite and polyamide. The effect of additives (polar organic solvents), the acyl-donor ester structure, the C-alpha protecting group of the nucleophile, enzyme loading, and substrate concentration were tested. The best reaction medium found was acetonitrile containing buffer (0.5%, v/v) and triethylamine (0.5%, v/v) using the enzyme deposited on Celite as catalyst (8 mg of alpha-chymotrypsin/g of Celite). A reaction yield of 81% was obtained with Z-Gly-Trp-OCam as acyl donor, at an initial concentration of 80 mM. The tripeptide synthesis was scaled up to the production of 2 g of pure tripeptide with an overall yield of 71%, including reaction and purification steps.
authors.affiliation: Unitat d'Enginyeria Química, Department de Química, Facultat de Ciències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Capellas
authors.forename: M D
authors.initials: MD
authors.lastname: Benaiges
authors.forename: G
authors.initials: G
authors.lastname: Caminal
authors.forename: G
authors.initials: G
authors.lastname: Gonzalez
authors.forename: J
authors.initials: J
authors.lastname: Lopez-Santín
authors.forename: P
authors.initials: P
authors.lastname: Clapés