An industrial alkaline protease "Alcalase" has been found to be very stable in organic solvents and usable as a catalyst for i) resolution of N-protected amino acids, in both aqueous solution and organic solvent with high yield and optical purity, ii) saponification of Fmoc-peptide esters in high concentration organic solvent iii) kinetically controlled peptide bond formation in ethanol solution, iv) diastereoselective hydrolysis of peptide esters, to prepare optically pure peptides.