Biosynthesis of myo-inositol in lycopods: characteristics of the pteridophytic l-myo-inositol-1-phosphate synthase and myo-inositol-1-phosphate phosphatase from the strobili of Lycopodium clavatum and Selaginella monospora.

摘要

Two key enzymes of myo-inositol metabolism [l-myo-inositol-1-phosphate synthase (MIPS) and myo-inositol-1-phosphate-phosphatase (MIPP)] were identified for the first time in Pteridophyta in Lycopodium clavatum and Selaginella monospora. Both enzymes from both plants were partly purified and the degree of purity obtained from 47 to 75 folds. MIPS preparations specifically utilized d-glucose-6-phosphate and NAD+ as its substrate and coenzyme with the K_m values for G-6-P and NAD+ were 1.74 and 0.34 mM in L. clavatum; 2.32 and 0.37 mM in S. monospora. MIPP preparations used d/l-myo-inositol-1-phosphate as its principal substrate with the K _m values for MIP was 0.068 mM in L. clavatum and 0.076 mM in S. monospora. The pH reliance of all the preparations was around 7.0-7.5 and different cations had variable role.