Enzymatic synthesis of N-acyl-l-amino acids in a glycerol-water system using acylase I from pig kidney

N-Medium- and long-chain acyl-l-amino acids were enzymatically synthesized from the corresponding l-amino acids and fatty acids using a reverse hydrolysis. Enzymes that are suitable for the synthetic reaction of N-acyl-l-amino acids were screened on the basis of hydrolytic activity toward N-lauroyl-l-glutamic acid as an indicator. Acylase I from pig kidney (EC 3.5.1.14) showed the highest N-acyl-l-amino acid hydrolytic activity among 57 commercially available enzymes tested. Acylase I effectively catalyzed the synthesis of N-lauroyl-l-amino acids except for N-lauroyl-l-proline and N-lauroyl-l-tyrosine in a glycerol-water system. Under the optimized reaction conditions, N-lauroyl-l-arginine and N-lauroyl-l-glutamic acid were obtained in conversions of 82 and 44%, respectively. The equilibrium constants calculated from the conversion obtained were 5.6, 15.4, 18.0, and 39.4 for the syntheses of N-lauroyl-l-glutamic acid, N_α-lauroyl-l-lysine, N-lauroyl-l-glutamine, and N-lauroyl-l-methionine, respectively. N-Acyl-l-arginines with myristic acid and palmitic acid as the fatty acid were also synthesized using acylase I.