Isolation and properties of protease a from wheat grain

To support the sulphydryl nature of the proteolytic enzymes of wheat grain, an isolation and purification procedure was devised by which the presence of at least two different proteases in the material studied was demonstrated. Protease A was shown to contain both reactive and masked sulphydryl groups. Low molecular weight reducing compounds appeared to activate the enzyme, whereas specific sulphydryl blocking and oxidising agents had a marked inhibitory effect. Thus, the sulphydryl‐dependent nature of the mechanism of activation and inhibition of wheat protease A was confirmed. When incubated with the wheat proteases, gluten appeared to be resistant to their proteolytic action. The wheat grain protease was active not only against protein substrates but also against some low molecular weight peptides. The enzyme preparation showed maximum activity at pH 5–6 for the substrates studied. All the experiments performed in the course of this study support the sulphydryl nature of wheat grain protease A.