R. Batt, W. Wallace
Feb 24, 1989
Citations
0
Influential Citations
6
Citations
Journal
Biochimica et Biophysica Acta
Abstract
A maize root endopeptidase which has maximum activity on N-t-butoxycarbonyl- L -alanine p-nitrophenyl ester (Boc-Ala-ONp) at pH 6.7 was inhibited by the histidine-specific reagents diethylpyrocarbonate and diethyl-p-nitrophenyl phosphate. Diisopropyl fluorophosphate also inhibited the endopeptidase indicating that it has the serine type reaction mechanism. It was not inhibited by iodoacetate or leupeptin but was inhibited by HgCl2. The high activity of the maize root enzyme on Boc-Ala-ONp and its inhibition by elastatinal suggest a similarity to elastase. The maize root endopeptidase gave a specific cleavage of the oxidized insulin B chain at the Ala14-Leu15 peptide bond. Only after prolonged treatment, or with high levels of the enzyme, did further hydrolysis of the two primary fragments of insulin occur.