Faculty of Biology, University of Latvia
Hard copy: ISSN 1691–8088
On-line: ISSN 2255–9582
Environ Exp Biol (2018) 16: 21–30
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Environmental and

Environ Exp Biol (2018) 16: 21–30

Orginal Paper

Isolation, partial purification and biochemical characterization of chloroplastic L-myo-inositol-1-phosphate synthase from a macro alga Enteromorpha intestinalis under high salinity

Sautrik Basu1*, Anusuya Basak2, Rajashree Bose2, Rukmini Chakrabarty2, Jukta Adhikari1,2
1 Post Graduate Department of Botany, Barasat Govt. College, 10, K.N.C Road, Kolkata 700 124, India
2 Biochemistry Laboratory, Department of Botany, Presidency College (Currently Presidency University), 86/1 College Street, Kolkata 700 073, India
* Corresponding author, E-mail: basusautrik@yahoo.co.in


Induction of higher myo-inositol biosynthesis in a salinity driven macro-alga, Enteromorpha intestinalis (L.) Nees, as a model macrophyte, grown under natural conditions was established on the basis of a study on its prime enzyme, L-myo-inositol-1-phosphate synthase (MIPS) and the accumulation of free myo-inositol in chloroplasts. This enzyme was partially purified from isolated chloroplasts obtained from the plant grown under higher salinity to about 41-fold over homogenate following low-speed centrifugation, high-speed centrifugation, 0 to 80% ammonium sulfate precipitation, successive chromatography through DEAE-cellulose, Sephadex G-200 and BioGel 0.5 m columns. The apparent Mr of the native enzyme was about 164 kDa. Temperature and pH optima were found to be 35°C and 7.5 respectively. D-glucose-6-phosphate and NAD were its exclusive substrate and coenzyme, respectively, with Km value 0.1761 mM for D-glucsoe-6-phosphate and 0.1695 mM for β-NAD as determined by non-linear regression kinetics method. Among the important monovalent and divalent cations tested, K+ had trivial stimulatory effect while Li+ was sturdily inhibitory. Divalent cations recorded variable effects. Ca2+ exhibited slight stimulatory effect and Cd2+ reduced MIPS activity faintly. Salts of Cu2+ and Hg2+ were found to be potent inhibitors of this enzyme. The concentration of free myo-inositol was found to increase proportionately with salinity at least up to 12 PSU.

Key words: chloroplast, Enteromorpha intestinalis, L-myo-inositol-1-phosphate synthase, marine macro alga, salinity.

Environ Exp Biol (2018) 16: 21–30
 DOI: http://doi.org/10.22364/eeb.16.03

Prof. Gederts Ievinsh
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