Aspergillus Protease-Catalyzed Esterification at pH > 7

Diverse N-substituted amino acids were converted to their corresponding esters by crude sucrose-immobilized Aspergillus oryzae protease in organic solvents at pH 7.5. The front part of captopril S-(-)-acetylthio-2-methylpropionic acid and the aspartame precursor Cbz-L-Asp-L-Phe-OH also underwent esterification under such conditions.