The dark (oxidized) form of the light‐activatable NADP‐malate dehydrogenase from pea chloroplasts is catalytically active in the presence of guanidine‐HCl

FEBS Letters

Fickenscher, K.¹  Scheibe, R.¹ 

[1] Lehrstuhl für Pflanzenphysiologie, Universität Bayreuth, Universitätsstr. 30. D-8580 Beyreuth, FRG

关键词: NADP-malate dehydrogenase;    Guanidine hydrochloride;    Pea chloroplast;    Light-activatable enzyme;    Oxidized-enzyme catalytic activity;   

DOI  :  10.1016/0014-5793(85)81094-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The dark form of NADP-malate dehydrogenase from pea leaves which has been shown to contain one disulfide bridge per subunit does not exhibit any catalytic activity in the absence of thiol reducing agents. Upon reduction of these disulfide bridges the enzyme becomes catalytically active. In this presentation, however, it is shown that the oxidized dark form of NADP-malate dehydrogenase becames catalytically competent when assayed in the presence of 200–250 mM guanidine-HCl. This guanidine-dependent activity of the oxidized enzyme is characterized by higher apparent K _m values for the substratres as compared to the reduced enzyme, but is still specific for NADPH. Up to 25% of the V _maxOf the reduced enzyme was obtained for the oxidized guanidine-activated NADP-malate dehydrogenase. The results suggest that the reduction of the regulatory disulfide is not essential for catalytic activity.

【 授权许可】

Unknown