On the interaction of substrate analogues with non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase from celery leaves

• Published in: Plant science (Limerick) 2002-05, Vol.162 (5), p.689-696
• Main Authors: Iglesias, Alberto A., Vicario, Lionel R., Gómez-Casati, Diego F., Sesma, Juliana I., Gómez-Casati, Marı́a E., Bustos, Diego M., Podestá, Florencio E.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Celery; Economic plant physiology; Enzymes; Fundamental and applied biological sciences. Psychology; GAPN; Glyceraldehyde-3-P analogues; Glyceraldehyde-3-phosphate dehydrogenase; Metabolism; NADP; Non-phosphorylating; Nutrition. Photosynthesis. Respiration. Metabolism; Plant physiology and development
• ISSN: 0168-9452; 1873-2259
• DOI: 10.1016/S0168-9452(02)00015-8

Structural 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, N 6-etheno-nicotinamide dinucleotide phosphate (εNADP +); and β-nicotinamide adenine dinucleotide 2′:3′-cyclic monophosphate (2′3′NADP +c) were alternative enzyme substrates, with a 2-fold variation in V max and 2–11-fold differences in K m 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 as competitive 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.