INVESTIGADORES
IGLESIAS Alberto Alvaro
artículos
Título:
Structural and Kinetic Characterization of NADP-Dependent, Non-Phosphorylating Glyceraldehyde-3-Phosphate Dehydrogenase from Celery Leaves
Autor/es:
D.F. GÓMEZ CASATI, J.I. SESMA Y A.A. IGLESIAS
Revista:
PLANT SCIENCE
Editorial:
Elsevier
Referencias:
Año: 2000 vol. 154 p. 107 - 115
ISSN:
0168-9452
Resumen:
AbstractNADP-dependent, non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.9) from celery leaves was purified over 1200-fold to a specific activity of 35 units:mg protein, and its kinetic, regulatory and structural properties were characterized. The purified enzyme exhibited a homotetrameric structure with a subunit molecular mass of 54 kDa. A high specificity of the enzyme for the substrates NADP (Km7 mM) and D-glyceraldehyde-3-phosphate (Km127 mM) was observed. Maximal activity was determined at pH 8.5. The purified enzyme was highly unstable, requiring the addition of NADP or conditions of high ionic strength in the medium. A hysteretic behavior, with a lag phase of minutes, was observed during activity measurement of the enzyme preincubated in the absence of substrates. The lag was inversely proportional to the protein concentration during preincubation. The hysteretic parameters were affected by the substrates, KCl and mannitol among other compounds. Distinctively, incubation with NADP produced a near twofold activation of the enzyme. Results suggest that in alditol producing plants the enzyme plays a key role in the synthesis and partitioning of photoassimilates. © 2000 Published by ElsevierScience Ireland Ltd. All rights reserved.Keywords: Alditols biosynthesis; Carbon partitioning; Celery leaves; Glyceraldehyde-3-phosphate dehydrogenase; Non-phosphorylating