Patent ID: 7569377

Claim:
A modified α-glucan phosphorylase having improved thermostability, which is obtained by modifying a natural α-glucan phosphorylase, wherein the natural α-glucan phosphorylase is obtained from a plant; wherein the α-glucan phosphorylase having improved thermostability has an amino acid substitution at a position corresponding to position 7 in a motif sequence 3L: R-I-V-K-F-I-T-D-V (SEQ ID NO: 47); wherein said substitution is a substitution to C, I, L, V, or W; wherein the α-glucan phosphorylase having improved thermostability has an amino acid sequence which is at least 95% identical to the sequence of the natural α-glucan phosphorylase of SEQ ID NO: 2; wherein the enzyme activity of the α-glucan phosphorylase having improved thermostability is equivalent or superior to the natural α-glucan phosphorylase; and wherein enzyme activity of the α-glucan phosphorylase having improved thermostability at 37° C., after heating in a 20 mM citrate buffer (pH 6.7) at 60° C. for 10 minutes, is 20% or more of enzyme activity of the α-glucan phosphorylase having improved thermostability at 37°C., before heating.