evidence for the essential arginine and histidine residues in catalytic activity of glucose 6-phosphate dehydrogenase from streptomyces aureofaciens

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چکیده

glucose 6-phosphate dehydrogenase (g6pd) was purified from streptomyces aureofaciens and inactivated with butanedione and diethylpyrocarbonate. incubation of the enzyme with butanedione resulted in a rapid activity loss (80%) within 5 min, followed by a slow phase using a molar ratio to enzyme concentration of 100. fluorescence studies showed a conformational change in the butanedione-modified enzyme. nad+, nadp+ and glucose 6-phosphate protected the enzyme against inactivation. diethylpyrocarbonate (2 mm) completely inactivated the enzyme after 2 min. stoichiometry of the inactivation showed 2 moles of histidine residues per mole of enzyme with complete activity loss. maximum emission spectrum of the enzyme decreased (23%) upon modification and the presence of nad+ or nadp+ further decreased the fluorescence by 27% and 10.5%, respectively. the data suggest that essential arginine and histidine residues may be involved in the catalytic activity of streptomyces aureofaciens g6pd

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Evidence for the Essential Arginine and Histidine Residues in Catalytic Activity of Glucose 6-Phosphate Dehydrogenase from Streptomyces aureofaciens

Glucose 6-phosphate dehydrogenase (G6PD) was purified from Streptomyces aureofaciens and inactivated with butanedione and diethylpyrocarbonate. Incubation of the enzyme with butanedione resulted in a rapid activity loss (80%) within 5 min, followed by a slow phase using a molar ratio to enzyme concentration of 100. Fluorescence studies showed a conformational change in the butanedione-modified ...

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involvement of essential lysine residues in the catalytic activity of glucose 6-phosphate dehyrogenase purified from streptomyces aureofaciens

glucose 6- phosphate dehydrogenase from streptomyces aureofaciens was purified andinactivated by pyridoxal 5′-phosphate (plp). the inactivation was a pseudo-first order and time-dependentreaction. complete inactivation was achieved at 0.2mm plp within 16 minutes. the type of inhibition wascompetitive with respect to glucose 6- phosphate. spectral characteristics of plp-enzyme complexcorresponde...

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Involvement of Essential Lysine Residues in the Catalytic Activity of Glucose 6-phosphate Dehyrogenase Purified from Streptomyces Aureofaciens

Glucose 6phosphate dehydrogenase from streptomyces aureofaciens was purified and inactivated by pyridoxal 5′-phosphate (PLP). The inactivation was a pseudo-first order and time-dependent reaction. Complete inactivation was achieved at 0.2mM PLP within 16 minutes. The type of inhibition was competitive with respect to Glucose 6phosphate. Spectral characteristics of PLP-enzyme complex corresponde...

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REASSOCIATION AND REACTIVATION OF GLUCOSE 6-PHOSPHATE DEHYDROGENASE FROM STREPTOMYCES AUREOFACIENS AFTER DENATURATION BY 6 M UREA

Glucose 6-phosphate dehydrogenase (G6PD) from Streptomyces aureofaciens was purified and denatured in 6 M urea. Denaturation led to complete dissociation of the enzyme into its inactive monomers, 98% loss of the enzyme activity, about 30% decrease in the protein fluorescence and a 10 nm red shift in the emission maximum. Dilution of urea-denatured enzyme resulted in regaining of the enzyme acti...

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interaction of nad+and nadp+with native and pyridoxal phosphate-modified glucose 6-phosphate dehydrogenase purified from streptomyces aureofaciens

interaction of glucose 6-phosphate dehydrogenase from s. aureofaciens with nad+, nadp+and glucose 6-phosphate were investigated using different fluorescent probes. binding of nad+, nadp+and s-nadph to the native enzyme quenched intrinsic protein fluorescence by 100%, 10% and 21%,respectively, from which kd values of nad+ (6.5 mm), nadp+ (92.0 μm) and s-nadph (122.0 μm)were calculated. binding o...

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glucose 6-phosphate dehydrogenase from streptomyces aureofaciens: ligand-induced conformational chang

some kinetic properties of nad+- and nadp+- dependent glucose 6-phosphatedehydrogenase (g6pd) purified from streptomyces aureofaciens were studied. both nadh andnadph inhibited the enzyme competitively and noncompetitively, with respect to the correspondingcoenzymes and glucose 6-phosphate, respectively. atp inhibited the nad+ - linked reaction but not thatof the nadp+- linked activity. the inh...

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عنوان ژورنال:
journal of sciences islamic republic of iran

جلد ۱۶، شماره ۱، صفحات ۰-۰

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