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THE BARLEY PROTEIN DEGRADATION: EFFECT OF NEUTRAL PROTEINASE CONCENTRATION ON PROTEIN DEGRADATION KINETICS
Author(s) -
Marković I.,
Topolovec V.,
Marić V.,
Johanides Vera
Publication year - 1984
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.1984.tb04225.x
Subject(s) - mashing , hydrolysis , degradation (telecommunications) , chromatography , chemistry , kinetics , enzyme , proteinase k , enzyme kinetics , hordeum vulgare , liberation , biochemistry , biology , active site , poaceae , botany , telecommunications , physics , quantum mechanics , computer science , in vitro
The time course of barley protein degradation was investigated in two cases: (i) in mashing of raw barley with different concentrations of bacterial neutral proteinase in the presence of α‐amylase. and (ii) in mashing of spent grains, remaining after barley syrup preparation, with different proteinase concentrations. Protein solubilisation and α‐amino nitrogen liberation rates decrease in the course of barley and spent grains hydrolysis. Initial protein degradation rates in spent grains mashing are lower than in native barley. Gel‐chromatography of supernatants of the mash in the course of hydrolysis has indicated that the proteinase becomes increasingly occupied with solubilised proteins as the process proceeds. plotting the kinetics data for protein solubilisation in Foster‐Niemann coordinates straight lines with high correlation (r=0·999) for both cases of hydrolysis have been obtained. For different enzyme concentrations the straight lines have been closely parallel with positive slope. A high correlation between ordinate intercept in Foster‐Niemann coordinates and proteinase concentrations has been obtained. Linear correlations in Foster‐Niemann coordinates for α‐amino nitrogen liberation process have also been observed. However, for α‐amino nitrogen liberation, the correlation between the ordinate intercept and proteinase concentration has not been achieved. The possibilities of application of kinetics parameters (ordinate intercept slope) as quantitative measures of enzyme efficiency in protein degradation under different conditions has been emphasised.