Activation‐dependent changes in microenvironment of spinach ribulose 1,5‐bisphosphate carboxylase/oxygenase

FEBS Letters

Bhagwat, Anil S.²  Verma, Naresh C.¹  Purohit, Ulka S.² 

[1] Radiation Biology Section, Bhabha Atomic Research Centre, Bombay-400 085, India;Molecular Biology and Agriculture Division, Bhabha Atomic Research Centre, Bombay-400 085, India

关键词: Ribulose bisphophate carboxylase;    Activation;    o-Phthalaldehyde;    Fluorescence;   

DOI  :  10.1016/0014-5793(91)80752-O

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The spinach ribulose 1,5-bisphosphate carboxylase/oxygenase was labelled with o-phthalaldehyde, which forms a stable fluorescent isoindole adduct at the active site. The fluorescence behaviour of the labelled enzyme after activation to different levels by Mg²⁺ was compared with that of a synthetic isoindole adduct of o-phthalaldehyde, namely 1-(hydroxyethylthio)-2-β hydroxyethylisoindole in solvents of different pH and polarity. The results suggest that the microenvironment at the catalytically incompetent active site of the unactivated Rubisco is highly acidic (pH < 2) in nature. The activation by Mg²⁺ results in the conformational change such that the effective pH at the active site increases to > 8. The polarity of the active site of the activated enzyme was found to be similar to that of a mixture of hexane and toluene.

【 授权许可】

Unknown