Enzymatic synthesis of arginine-based cationic surfactants

A novel enzymatic approach for the synthesis of arginine N-alkyl amide and ester derivatives is reported. Papain deposited onto solid support material s was used as catalyst for the amide and ester bond formation between Z-Arg -OMe and various long-chain alkyl amines and alcohols (H2N-C-n, HO-C-n; n = 8-16) in organic media. Changes in enzymatic activity and product yield we re studied for the following variables: organic solvent, aqueous buffer con tent, support for the enzyme deposition, presence of additives, enzyme load ing, substrate concentration, and reaction temperature. The best yields (81 -89%) of arginine N-alkyl amide derivatives were obtained at 25 degrees C i n acetonitrile with an aqueous buffer content ranging from 0 to 1% (v/v) de pending on the substrate concentration. The synthesis of arginine alkyl est er derivatives was carried out in solvent-free systems at 50 or 65 degrees C depending on the fatty alcohol chain length. In this case, product yields ranging from 86 to 89% were obtained with a molar ratio Z-Arg-OMe/fatty al cohol of 0.01. Papain deposited onto polyamide gave, in all cases, both the highest enzymatic activities and yields. Under the best reaction condition s the syntheses were scaled up to the production of 2 g of final product. T he overall yields, which include reaction, N-alpha-benzyloxycarbonyl g roup (Z) deprotection a nd purification, varied from 53 to 77% of pure (99.9% b y HPLC) product. (C) 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 63: 333 -343, 1999.