Partial Purification and Properties of l-Glutamine d-Fructose 6-Phosphate Amidotransferase from Phaseolus aureus1
AUTOR(ES)
Vessal, Mahmood
RESUMO
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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=366091Documentos Relacionados
- Feedback Inhibition of l-Glutamine d-Fructose 6-Phosphate Amidotransferase by Uridine Diphosphate N-Acetylglucosamine in Neurospora crassa
- Metabolism of d-Fructose in Aerobacter aerogenes: Analysis of Mutants Lacking d-Fructose 6-Phosphate Kinase and d-Fructose 1,6-Diphosphatase1
- Partial Purification and Properties of d-Glucosamine 6-Phosphate N-Acetyltransferase from Phaseolus aureus1
- D-fructose dehydrogenase of Gluconobacter industrius: purification, characterization, and application to enzymatic microdetermination of D-fructose.
- Phosphoenolpyruvate-dependent formation of D-fructose 1-phosphate by a four-component phosphotransferase system.