1. The binding of substrates and effectors to glucosamine synthetase (l-glutamine–d-fructose 6-phosphate aminotransferase, EC 18.104.22.168) was studied by using the ligand to alter the denaturation rate of the enzyme. The free enzyme bound fructose 6-phosphate, glucose 6-phosphate and UDP-N-acetylglucosamine, but not glutamine, AMP or UTP. Glucose 6-phosphate and AMP increased the binding of UDP-N-acetylglucosamine whereas UTP decreased the interaction between the enzyme and the feedback inhibitor. UDP-N-acetylglucosamine induced a glutamine-binding site on the enzyme. 2. Selective thermal or chemical denaturation revealed that the UDP-N-acetylglucosamine-binding site was not located at the catalytic site. The UTP site could not be distinguished from that for the nucleotide sugar. The AMP- and glucose 6-phosphate-binding sites were distinct from the catalytic and feedback-inhibitor-binding sites. 3. The specificity of the glutamine-binding site was investigated by using a series of potential analogues. 4. A model is proposed for the action of the effectors and the mechanism of the reaction discussed in kinetic and chemical terms.
Research Article| February 01 1971
The binding of substrates and modifiers to glucosamine synthetase
P. J. Winterburn;
Biochem J (1971) 121 (4): 721–730.
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P. J. Winterburn, C. F. Phelps; The binding of substrates and modifiers to glucosamine synthetase. Biochem J 1 February 1971; 121 (4): 721–730. doi: https://doi.org/10.1042/bj1210721
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