RECONSTITUTION OF PHASEOLUS-VULGARIS ALPHA-AMYLASE INHIBITOR FROM ISOLATED SUBUNITS

The reconstitution of Phaseolus vulgar is alpha-amylase inhibitor from its two kinds of subunits was studied. The inhibitor was reconstitute d by quick dilution from its subunits denatured in 6 M guanidine hydro chloride with a concomitant restoration of the inhibitory activity. Va rious environmental factors had a profound influence on the rate and e xtent of the reconstitution. Especially low protein concentration and high ionic strength were essential for a high yield of regained activi ty, and Zn2+ was also effective in promoting reconstitution. The maxim um specific activity of reconstituted inhibitor was obtained at a 1:1 molar ratio of alpha-subunit: beta-subunit. Under the optimal conditio ns obtained, the activity regain was about 60% of the activity of the native inhibitor. Further, this report advances the possibility that t he glycan chains of each subunit may be important in proper folding an d assembly of the subunit polypeptides.