Seed Proteinase Inhibitors of Pulchellae, Acacia mitchellii Benth. And A. alata R. Br.: Exclusion of A. mitchellii From Pulchellae

Abstract

Seed trypsin and chymotrypsin inhibitory activities (as mg enzyme inhibited per g of seed meal) and the electrophoretic patterns of trypsin and chymotrypsin inhibitors (TI and CTI respectively) have been studied in representatives of Pulchellae and in Acacia alata R. Br., a species incorporated into the broad group 'Pulchelloidea' Vassal. The value of TI obtained for Acacia mitchellii Benth. (9.4) is one of the highest recorded for an Australian acacia, and compares with a range of values from 0.9 to 3.8 for Pulchellae s. str. The value of CTI measured for A. mitchellii (3 , 1) is also well above the range of 0.6 -1.9 obtained from Pulchellae s. str. The exclusion of A. mitchellii from Pulchellae is further supported by its possession of a type A electrophoretic pattern, in which the main bands of TI activity lack detectable CTI activity. By comparison, all members of Pulchellae s. str. so far examined display type B patterns, in which the mobilities of the CTI bands are both equal to and greater than the mobilities of the main bands of TI activity. Although A. alata displayed a type A rather than a type B pattern, its TI and CTI activities (1.8 and 1.6 respectively) were within the ranges displayed by Pulchellae s. str. and its electrophoretic profile of seed proteins resembled those of members of the A. browniana subgroup of Pulchellae s. str.