Myo-Inositol is an important metabolite for normal growth and development of all living organisms. The cellular level of
myo-inositol is controlled by the enzyme L-
myo- inositol-1-phosphate synthase (MIPS) [EC 5.5.1.4]. Appreciable level of MIPS activity was detected from the common pteridophytes
like
Dicranopteris, Diplazium, Diplopterygium, Equisetum, Lycopodium, Polypodium, Pteridium, Selaginella etc. available in Darjeeling Himalayas. The enzyme was partially purified from the reproductive pinnules of
Diplopterygium glaucum (Thunb.) Nakai. The purification obtained was about 81 fold and the recovery was about 13.5 %. The final enzyme preparation
specifically utilized D-Glucose-6-phosphate and NAD+ as its substrate and co-factor respectively. It shows pH optima between
7.0 and 7.5 while the temperature maximum was at 35 °C. The enzyme activity was slightly inhibited by Na
+ and Cd
2+ and highly inhibited by Li
+ and Hg
2+. The
K
rn values for D-glucose-6-phosphate and NAD+ was found to be as 0.83 mM and 0.44 mM respectively while the
V
max values were 1.42 mM and 1.8 mM for D-glucose-6-phosphate and NAD+ respectively. The present study indicates the universal
occurrence of this enzyme in all plant groups.
Key words D-glucose-6-phosphate -
Diplopterygium glaucum
- enzyme purification -
myo-Inositol - Pteridophytes