Bioprospecting for enzymes in bryophytes: Extraction of L-Myo-inositol-1-phosphate synthase from Sphagnum junghuhnianum Doz. et Molk. and its characterization.

• Myo-inositol synthesizes several biochemical components in living systems. • L- myo -inositol-1-phosphate synthase is the principal enzyme for myo-inositol biosynthesis. • Myo-inositol derivatives influence abiotic stress tolerance in plants. • The activity of the rate limiting enzyme is higher in desiccation tolerant bryophytes. L- myo -inositol-1-phosphate synthase (MIPS) and its product, free myo- inositol have been isolated from different bryophytes. MIPS was purified for the first time from the moss, Sphagnum junghuhnianum to 58.67 fold over its homogenate fraction with about 32.86 % recovery. D-glucose-6-phosphate was the exclusive substrate of the enzyme without which there was no enzyme activity and the deduction of NH 4 Cl, ME and NAD+ substantially reduced the activity of the enzyme. The K m for D-glucose-6-phosphate and NAD+were 1.81 mM and 0.25 mM, while the V max for the same were 1.42 mM and 1.12 mM respectively. The molecular weight of the enzyme was assessed to be approximately 174 kDa. The activity of the enzyme increased with the increase in the duration of incubation time for up to 90 min and with the increase in protein concentration for up to 300 µg. The pH and temperature maxima were pH 7.0 and at 30 °C, respectively, but a significant activity was observed at 10 °C also. NH 4 Cl substantially stimulated the enzyme activity while K + and Ca2+ also raised the activity slightly. Li+ greatly inhibited the activity. Inhibitory activity was also shown by Cd2+, Mn2+, Zn2+and Hg2+ of which Hg2+ showed the maximum inhibition. Interestingly, the Sphagnum junghuhnianum MIPS showed the characteristics of both Class-II and Class-III aldolase. [ABSTRACT FROM AUTHOR]