Abstract
Summary
The cytoplasmic, particulate, and cell wall fractions were isolated from disrupted bacterial cells and assayed for MADH, GDH, HX, and GLD enzymes in absence of pigment (control) and presence of various M-3-G concentrations. The magnitude of enzymatic inhibition due to increasing concentrations of M-3-G (1 to 4 μM) was not the same for each enzyme. Two μM of M-3-G inhibited glycerol dehydrogenase (35% of control) in particulate fraction, whereas, 76% inhibition was noted in cytoplasmic fraction with 4 μM of pigment. MADH was inhibited to the extent of 10 and 20% in particulate fraction with 2 and 4 μM of M-3-G respectively and 4% in cytoplasm with both pigment concentrations. For comparative purposes, the effect of M-3-G on the same enzymes obtained commercially from other sources revealed that GDH (Aerobacter aerogenes) was inhibited 85% with 4 μM pigment. Inhibition (87%) of MADH (pig heart) and (17%) GLD (Escherichia coli) was noted with 2 μM M-3-G. Stimulation of HX (yeast) (21% over control) was observed with 1 μM M-3-G; 2 μM had no effect, whereas 4 μM caused 6% inhibition. Competitive and non-competitive inhibition of GLD by M-3-G, depending on how substrate, inhibitor and enzyme were mixed, followed Michaelis-Menton kinetics as indicated by the linear relationship in the Lineweaver-Burk plot with Km = 2.3 × 10-5 M for enzyme and inhibitor equilibrated together and substrate added at zero time.
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