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. 1972 Jun;49(6):977–981. doi: 10.1104/pp.49.6.977

Partial Purification and Properties of l-Glutamine d-Fructose 6-Phosphate Amidotransferase from Phaseolus aureus1

Mahmood Vessal a,2, W Z Hassid a
PMCID: PMC366091  PMID: 16658095

Abstract

l-Glutamine d-fructose 6-phosphate amidotransferase (EC 2.6.1.16) was extracted and purified 600-fold by acetone fractionation and diethylaminoethyl cellulose column chromatography from mung bean seeds (Phaseolus aureus). The partially purified enzyme was highly specific for l-glutamine as an amide nitrogen donor, and l-asparagine could not replace it. The enzyme showed a pH optimum in the range of 6.2 to 6.7 in phosphate buffer. Km values of 3.8 mm and 0.5 mm were obtained for d-fructose 6-phosphate and l-glutamine, respectively. The enzyme was competitively inhibited with respect to d-fructose 6-phosphate by uridine diphosphate-N-acetyl-d-glucosamine which had a Ki value of 13 μm. Upon removal of l-glutamine and its replacement by d-fructose 6-phosphate and storage over liquid nitrogen, the enzyme was completely desensitized to inhibition by uridine diphosphate-N-acetyl-d-glucosamine. This indicates that the inhibitor site is distinct from the catalytic site and that uridine diphosphate-N-acetyl-d-glucosamine acts as a feedback inhibitor of the enzyme.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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