Purification and properties of a protease from the sarcocarp of bead tree fruit.
A protease was purified from bead tree fruit (Melia azedarach L. var. japonica Makino) in four steps, including HPLC gel-filtration. The M(r) of the enzyme, named melain, was estimated to be 25,000 on SDS-PAGE and on HPLC gel filtration. Melain contained a carbohydrate moiety. Using casein as a substrate, the optimum pH of the enzyme was 7.5-8.5 at 37 degrees. The enzyme was inhibited by iodoacetic acid, but was not inhibited by phenylmethanesulphonyl fluoride or EDTA. The enzyme had a wide specificity for peptide substrates such as oxidized insulin B-chain. All split sites (P1 and/or P'1) were hydrophobic or charged amino acid residues. The enzymatic properties of this protease were similar to those of phytolacain, an enzyme from the fruit of pokeweed, Phytolacca americana.
Kaneda
M
M
Department of Chemistry, Faculty of Science, Kagoshima University, Japan.
Arima
K
K
Yonezawa
H
H
Uchikoba
T
T
D000595:Amino Acid Sequence; D002364:Caseins / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000302:isolation & purification* / Q000378:metabolism; D010450:Endopeptidases / Q000302:isolation & purification* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000378:metabolism; D007461:Iodoacetates / Q000494:pharmacology; D019807:Iodoacetic Acid; D007564:Japan; D008969:Molecular Sequence Data; D010946:Plants, Medicinal / Q000201:enzymology*; D011480:Protease Inhibitors; D013379:Substrate Specificity
D002364:Caseins; D007328:Insulin; D007461:Iodoacetates; D011480:Protease Inhibitors; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; C087622:melain; D019807:Iodoacetic Acid