On the Interaction of Substrates’ Analogues with Non-Phosphorylating Glyceraldehyde-3-Phosphate Dehydrogenase from Celery Leaves

A.A. IGLESIAS, L.R. VICARIO, D.F. GÓMEZ CASATI, J.I. SESMA, M.E. GÓMEZ CASATI, D.M. BUSTOS, F.E. PODESTÁ

PLANT SCIENCE

Elsevier

Año: 2002 vol. 162 p. 689 - 696

0168-9452

AbstractStructural analogues of D-glyceraldehyde-3-phosphate (D-Ga3P) and NADP were studied as potential substrates and inhibitors of the non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.9; GAPN) from Apium graveolens leaves. Four analogues of NADP: nicotinamide-hypoxanthine dinucleotide phosphate (NHDP);3- acetylpyridine- adenine dinucleotide phosphate (APADP); 1,N6-etheno-nicotinamide dinucleotide phosphate (oNADP); and b-nicotinamide adenine dinucleotide 2?:3?-cyclic monophosphate (2?3?NADPc) were alternative enzyme substrates, with a 2-fold variation in Vmax and 2/11-fold differences in Km compared to NADP. These compounds were also able to affect the hysteretic behavior of celery GAPN, in a similar way as the substrate NADP. The analogues to the nicotinamide moiety: thionicotinamide and 3-aminopyridine, behaved ascompetitive inhibitors, exhibiting a high-affinity binding to the enzyme. All the analogues of D-Ga3P that were analyzed behaved as competitive inhibitors, except for the L-isomer of the substrate which at relatively high concentrations exhibited a non-competitive effect. Results showed the importance of: (i) the chemical group at carbon-1 of Ga3P; (ii) the presence of a phosphate ester at carbon-3, and (iii) the stereochemical configuration at carbon-2. The particular behavior of L-Ga3P is analyzed by differences in tridimensional structure between bacteria and plant GAPNs. # 2002 Elsevier Science Ireland Ltd. All rights reserved.Keywords: Non-phosphorylating; Glyceraldehyde-3-phosphate dehydrogenase; GAPN; Celery; NADP; Glyceraldehyde-3-P analogues