Characterization and Application of Maltose Phosphorylase and Trehalose Phosphorylase from a Marine Bacterium, Plesiomonas SH-35
Masahiro YOSHIDA*a, Nobuyuki NAKAMURAa, and Koki HORIKOSHIb
a Research Institute, Nihon Shokuhin Kako Co., 30 Tajima, Fuji, Shizuoka 417, Japan
b Department of Technology, Toyo University, 2100 Kujirai, Kawagoe-shi 350, Japan
A strain of Plesiomonas capable of producing intra-cellular maltose phosphorylase (MP) and trehalose phosphorylase (TP) was isolated from mud of a Japanese seashore. Both purified enzymes showed optimum activities around pH 7.0- 7.5 and their optimum temperatures were about 50℃. MP and TP were stable over the range of pH 5.5-7.0 and 6.0-9.0, and retained the full activities up to about 40 and 45℃, respectively. Both phosphorylases catalyzed the following reversible reactions in the presence of inorganic phosphate (Pi).
Maltose or Trehalose + Pi = β-Glucose-1-phosphate (G-l-P) + Glucose Equilibrium constants, [Maltose or Trehalose][Pi]/[G-1-P][Glucose], for both reactions were 6.7 for MP and 11.3 for TP, respectively. In the phosphorolytic reaction of MP, values of Km for maltose and Pi were 2.0 and 11 mM, respectively. For the same reaction of TP, those of Km were 0.89 for trehalose and 6.7 for Pi, respectively. The TP activity was inhibited remarkably by Validamycin, but MP was not. By the simultaneus action of MP and TP at pH 7.0-8.0 and 55-60℃ in the presence of 5-50mM Pi and 10-40% (w/w) maltose as substrate, about 63% of maltose was converted into trehalose after removing G-1-P from the mother liquor.
