1983 Volume 103 Issue 6 Pages 655-661
An esterase was separated from the exocarp of Citrus natsudaidai HAYATA in a highly purified from. The enzyme hydrolyzes p-nitrophenyl esters of fatty acids, phenyl acetate, and tosylarginine methyl ester at varing rates. Of the substrates tested, p-nitrophenyl acetate, for which the specific activity was determined to be 18.60 units per mg of protein, was most rapidly hydrolyzed. The esterase was free from carboxypeptidase and other proteolytic activities. The esterase had a pH optimum at pH 5.5 for p-nitrophenyl acetate. It was strongly inhibited by HgCl2. The other metal ions or inorganic anions tested showed no significant effect on the enzymatic activity. The values of s20, w and D20, w were 1.8 S and 4.5×10-7cm2/s, respectively, and the molecular weight was calculated to be 40000 from these values. The enzyme was composed of 323 amino acid residues : Trp2, Lys21, His9, Arg10, Hyp23, Asp24, Thr18, Ser35, Glu22, Pro20, Gly40, Ala22, Cys(half)2, Val18, Met3, Ile12, Leu17, Tyr14, Phe11.
