The regulation and catalytic mechanism of the NADP-malic enzyme from tobacco leaves

0337488 - ÚEB 2010 RIV CS eng J - Článek v odborném periodiku
Doubnerová, V. - Potůčková, L. - Müller, Karel - Ryšlavá, H.
The regulation and catalytic mechanism of the NADP-malic enzyme from tobacco leaves.
[Regulace a mechanismus katalýzy NADP dependentní malátdehydrogenasy (dekarboxylační) z listů tabáku.]
Journal of the Serbian Chemical Society. Roč. 14, 8-9 (2009), s. 893-906. ISSN 0352-5139. E-ISSN 0352-5139
Výzkumný záměr: CEZ:AV0Z50380511
Klíčová slova: NADP-malic enzyme * macroergic compounds * Nicotiana tabacum L.
Kód oboru RIV: ED - Fyziologie
Impakt faktor: 0.820, rok: 2009

The non-photosynthetic NADP-malic enzyme EC 1.1.1.40 (NADP-ME), which catalyzes the oxidative decarboxylation of L-malate and NADP(+) to produce pyruvate and NADPH, respectively, and which could be involved in plant defense responses, was isolated from Nicotiana tabacum L. leaves. The mechanism of the enzyme reaction was studied by the initial rate method and was found to be an ordered sequential one. Regulation possibilities of purified cytosolic NADP-ME by cell metabolites were tested. Intermediates of the citric acid cycle (a-ketoglutarate, succinate, fumarate), metabolites of glycolysis (pyruvate, phosphoenolpyruvate, glucose-6-phosphate), compounds connected with lipogenesis (coenzyme A, acetyl-CoA, palmitoyl-CoA) and some amino acids (glutamate, glutamine, aspartate) did not significantly affect the NADP-ME activity from tobacco leaves. In contrast, macroergic compounds (GTP, ATP and ADP) were strong inhibitors of NADP-ME.

Nefotosyntetická forma NADP dependentní malátdehydrogenasy (dekarboxylační), dále jen NADP ME, katalyzuje oxidační dekarboxylace L-malátu a NADP+ za tvorby pyruvátu a NADPH. Etntoy enzym, který se pravděpodobně účastní obranných drah rostlin, byl izolován z listů tabáku. Byl sledován mechanismus katalýzy a vliv některých metabolitů na aktivitu enzymu. Meziprodukty citrátového cyklu, metabolity glykolýzy, sljoučeniny spojené s glykogenezí ani vybrané aminokyseliny neměly žádný vliv na aktivitu NADP ME. Naopak makroergní sloučeniny jako ATP, GTP a ADP měly silný inhibiční účinek.
Trvalý link: http://hdl.handle.net/11104/0181468