Protein breakdown and protease properties of germinating maize endosperm |
| |
Authors: | Thérèse Moureaux |
| |
Affiliation: | Laboratoire d''Etude des Protéines, Physiologie et Biochemie Végétales, I.N.R.A.-78 000 Versailles, France |
| |
Abstract: | Protein breakdown during germination of maize at 28° is closely correlated with the appearance of protease activity. In the first 2 days of germination, a slight disaggregation of only G3 glutelins into more simple elements (albumin-globulins) can be observed. Between 2 and 2.5 days, there is extensive breakdown of all protein fractions, the rate of which coincides with the rate of appearance of proteolytic activity. After 2.5 days these phenomena slow down and the bulk of the endosperm proteins disappears. Three acid proteases in endosperm extracts of germinated grain (P11, P21 and P22) have been isolated by affinity chromatography and gel filtration, and partially characterized. P11 (MW 40 000) which is present in the ungerminated grain, cannot hydrolyse prolamins and is insensitive to reducing agents. P21 (MW 36 000) and P22 (MW 12 000), which appear on day 3 of germination, can degrade prolamins in vitro. Reducing agents enhance their activity and prevent their aggregation or denaturation. Comparative assays with different substrates suggest our enzyme preparations are principally endotype proteases with little contaminating carboxypeptidase activity. |
| |
Keywords: | Gramineae maize germination protease endosperm protein hydrolysis. |
本文献已被 ScienceDirect 等数据库收录! |
|