SPECIFICITY OF ACTION OF THE WHEAT BUG {NYSIUS MUTTON!) PROTEINASE

摘要

The New Zealand wheat bug (Nysius huttoni) injects a salivary proteinase into immature wheat kernels while feeding. This proteinase remains in flour made from bug-damaged wheat, and in dough digests gluten to produce slack, sticky dough and poor quality bread. A micro-assay for iVjwus-proteinase was developed using gluten as substrate2, and the enzyme was purified and characterised as a serine proteinase'. Early attempts to develop an assay2"4 showed that the enzyme did not act on several proteins and synthetic substrates commonly used for assay of proteases. The enzyme did, however, specifically hydrolyse the high molecular weight glutenin subunits (HMW-GS) of glutenin.1'4 This paper describes enzyme specificity tests on a range of proteins and synthetic peptides, and reports the site of /Vy.y/M.y-proteinase action on HMW-GS 2, P-casein and K-casein.