A study of membrane-bound proteinase in rabbit periodontium

Abstract

A neutral endopeptidase in the microsome of the periodontal membrane of rabbit was measured with heat-denatured casein as a substrate, and some properties were investigated.
1. The endopeptidase showed maximal activity in the presence of cysteine and glutathione.
2. The endopeptidase seemed to hydrolyse casein limitedly, and the molecular weight of the endproduct was estimated within the range 1000-4000.
3. The endopeptidase was most active at pH 7.3.
4. The endopeptidase was strongly inhibited by 1mM EDTA, and reactivated to about 80% by Mg²⁺.
5. The enzyme is the only neutral endopeptidase shown to be bo und to the microsame of the periodontal membrane of rabbit.