Fractionation of the β-glucosidases from Aspergillus niger

The enzymic degradation of laminarin. 2. The multicomponent nature of fungal laminarinases

“…During the present investigations we have been able to separate figlucosidase components of low specificity from the fl-D-(1-÷3)-glucanases that are specific in action for laminarin. Our results are in close agreement with those of Duncan, Manners & Ross (1956), and Krishna Murti & Stone (1961), which suggest that specific P-(1-*3)and f-(1->4)glucanases do exist. In addition we have been able to characterize the action of ,B-(1-3)-glucanases and have isolated both exo-and endo-hydrolytic components.…”

“…Stone (1957) found that the cellulolytic enzymes of Aspergillus niger could be separated from three laminarin-hydrolysing components by adsorption chromatography on calcium phosphate. This finding has been confirmed by chromatography on Dowex 1 columns (Krishna Murti & Stone, 1961), but some coincidence of laminarinand cellobiosehydrolysing activity was observed. These authors were unable to decide whether this coincidence was due to (a) the presence of linkage-specific ,-glucosidases with similar physical properties, or (b) the presence of f-glucosidases whose specificities were not directed towards the position of the glucosidic linkage in the substrate.…”

The Biochemistry of Laminarin and the Nature of Laminarinase

“…Further work (111) supported this picture and confirmed the existence of specific p-1,3 and /3-1,4 glucanases. Calcium phosphate was used to resolve the laminarinase from Streptomyces species S93 (1 13) which was found to comprise two endo-p-1,3 glucanases (50 and 31%) and a smaller exo-/3-1,3 glucanase (19%).…”

“…Krishna Murti and Stone (111) stressed caution in attaching too much significance to the results of glucosidase fractionation experiments. They suggested that enzyme multiplicity of this type could have its basis, at least in part, in (1) changes in enzyme protein molecules without the loss of activity and (2) association of enzyme protein with other niat,erials, phenomena which would produce complex elution diagrams on chromatography.…”

The enzymic degradation of laminarin. 3. Some effects of temperature pH and various chemical reagents on fungal laminarinases

“…Two points should be emphasized in the light of our results on microbial laminarinase systems: the possible physical properties of laminarinase components from different sources and the degree of purity of the preparations. Krishna Murti & Stone (1961) have discussed physical aspects of fractionated f-glucosidases and suggest that the following are important in evaluating their action: (a) different forms of proteins may possess a similar biological activity; (b) changes in protein molecules due to hydrolysis of peptide or amide bonds may occur without loss of biological activity; (c) part of a protein complex may be associated with other material and this may be responsible for the appearance of several components.…”