GLUCOSAMINE-6-PHOSPHATE DEAMINASE FROM BEEF KIDNEY IS AN ALLOSTERIC SYSTEM OF THE V-TYPE

The enzyme glucosamine-6-phosphate deaminase from beef kidney has been purified to homogeneity by allosteric-site affinity chromatography. I ts amino acid composition and the N-terminal sequence (1-42), were obt ained. The amino acid sequence of this segment is essentially identica l to the corresponding regions of the human and hamster glucosamine-6- phosphate deaminases. The beef enzyme is a hexamer of 32.5 kDa subunit s; this is nearly 2.5 kDa higher than the molecular mass of the homolo gous enzyme from Escherichia coli. Beef kidney deaminase exhibits a no table difference from the bacterial enzyme in its allosteric activatio n by N-acetylglucosamine 6-phosphate This metabolite, which is also is the allosteric activator of the bacterial glucosamine-6-phosphate dea minase, activates the enzyme by increasing its k(cat) without any chan ge in the K-m values for glucosamine 6-phosphate, over a wide range of activator concentration. This observation places beef kidney deaminas e in the class of V-type allosteric systems. (C) 1998 Elsevier Science B.V. All rights reserved.