Further evidence for a role of sulfhydryls in the thioredoxin dependent activation of corn NADP‐malate dehydrogenase

FEBS Letters

Decottignies, Paulette¹  Jacquot, Jean-Pierre¹ 

[1] Physiologie Végétale Moléculaire, Bâtiment 430, U A 1128 CNRS, 91405 Orsay Cedex, France

关键词: Mutant Thioredoxin Malate dehydrogenase (NADP+) Redox reaction Light regulation;   

DOI  :  10.1016/0014-5793(86)81089-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The kinetics of activation and reduction of the corn leaf NADP-malate dehydrogenase reveal that plant thioredoxins play a dual role in the activation of this enzyme in the presence of dithiothreitol (e.g. reductive and conformational). A mutant thioredoxin of E. coli in which Cys₃₂ and Cys₃₅ are replaced by an Ala and a Ser residue, respectively, was tested in the activation of corn NADP-malate dehydrogenase either in the presence of DTT or in a light reconstituted system. While native E. coli or plant thioredoxin_m strongly activated the NADP-malate dehydrogenase, the mutant thioredoxin was unable to promote any activation of the enzyme. At the same time the mutant thioredoxin stimulated the activity of T₇ DNA polymerase. These results clearly confirm that the thioredoxin requirement observed in the activation of NADP-malate dehydrogenase is primarily needed for redox reactions and not for structural/conformational effects as is the case for the T₇ DNA polymerase assay.

【 授权许可】

Unknown