Purification and properties of phosphorylase from white yam tuber (Dioscorea rotundata) |
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Authors: | U Oluoha |
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Institution: | (1) Department of Biochemistry, University of Benin, Benin City, Nigeria |
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Abstract: | α-Glucan phosphorylase was extracted fromDioscorea rotundata tubers and purified 55 fold with specific activity of 360 nmol min-1 mg-1 protein and a yield of 41.5 %. By electrophoresis of purified enzyme on polyacrylamide gel a single band of phosphorylase
activity appeared. The enzyme showed normal Michaelis-Menten kinetics and was activated by AMP. ATP, ADP, ADP-glucose, calcium
and magnesium inhibited the enzyme. It is active in the presence and absence of primer. No effects were observed on the addition
of glycolytic intermediates or amino acids. Using gel filtration molecular mass of the enzyme determined is 188 000 and the
extract seems to contain one form. Properties of the enzyme indicate that phosphorylase from white yam tuber functions primarily
as a starch degrading enzyme. The possible role of the enzyme during yam tuber storage is dicussed. |
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