Interaction of pyridoxal phosphate with the amino groups at the active site of 5- aminolevulinic acid dehydratase in maize |
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Authors: | G B Maralihalli A S Bhagwat |
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Institution: | (1) Biology and Agricultural Division, Bhabha Atomic Research Centre, Trombay, 400085 Bombay, India |
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Abstract: | Pyridoxal 5′-phosphate strongly and reversibly inhibited maize leaf 5-amino levulinic acid dehydratase. The inhibition was
linearly competitive with respect to the substrate 5-aminolevulinic acid at pH values between 7 to 9.0. Pyridoxal was also
effective as an inhibitor of the enzyme but pyridoxamine phosphate was not inhibitory. The results suggest that pyridoxal
5′-phosphate may be interacting with the enzyme either close to or at the 5-aminolevulinic acid binding site. This conclusion
was further corroborated by the detection of a Schiff base between the enzyme and the substrate, 5-aminolevulinic acid and
by reduction of pyridoxal phosphate and substrate complexes with sodium borohydride |
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Keywords: | Dehydratase pyridoxal 5′ -phosphate aminogroups Zea mays |
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