Waters S P, Dalling M J
Plant Sciences Section, School of Agriculture and Forestry, University of Melbourne, Parkville, Victoria 3052 Australia.
Plant Physiol. 1984 May;75(1):118-24. doi: 10.1104/pp.75.1.118.
The isolation and characterization of the AP1 form of aminopeptidase (EC 3.4.11.) previously identified (Waters, Dalling 1979 Aust J Plant Physiol 6: 595-606) in the primary leaves of wheat (Triticum aestivum L. cv Egret) seedlings is reported. The enzyme shows a high preference for a substrate which contains an aromatic side chain, whether this be either a synthetic beta-naphthylamide or a peptide substrate. Maximum activity with both types of substrates occurred around pH 7.6. The stability of AP1 was reduced by exposure to high pH and by incubation at temperatures above 20 degrees C in the absence of substrate. AP1 was inhibited by the metal chelators bathocuproine and bathophenanthroline and the sulfhydryl group inhibitors p-chloromercuribenzoate and N-ethylmaleimide. The molecular weight, estimated by gel filtration, was 57,000. The K(m) value for activity against the synthetic substrate Phe-beta-NA (0.20 millimolar) was slightly lower than that for Phe-Phe (0.50 millimolar) although the enzyme activity against peptide substrates was considerably greater than with Phe-beta-NA.
本文报道了从小麦（Triticum aestivum L. cv Egret）幼苗初生叶中分离并鉴定先前已确定的氨肽酶（EC 3.4.11.）的AP1形式（Waters, Dalling 1979 Aust J Plant Physiol 6: 595 - 606）。该酶对含有芳香族侧链的底物表现出高度偏好，无论是合成的β - 萘酰胺还是肽底物。两种类型底物的最大活性都出现在pH 7.6左右。暴露于高pH值以及在无底物情况下于20摄氏度以上孵育会降低AP1的稳定性。AP1受到金属螯合剂邻二氮菲和bathophenanthroline以及巯基抑制剂对氯汞苯甲酸和N - 乙基马来酰亚胺的抑制。通过凝胶过滤估计的分子量为57,000。尽管该酶对肽底物的活性远大于对Phe - β - NA的活性，但针对合成底物Phe - β - NA（0.20毫摩尔）的活性的K(m)值略低于针对Phe - Phe（0.50毫摩尔）的K(m)值。
