Open Access2′‐Carboxy‐D‐arabitinol 1‐phosphate protects ribulose 1,5‐bisphosphate carboxylase/oxygenase against proteolytic breakdown
Author(s) -
Khan Shahnaz,
Andralojc P. John,
Lea Peter J.,
Parry Martin A. J.
Publication year - 1999
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1999.00913.x
Subject(s) - rubisco , ribulose 1,5 bisphosphate , biochemistry , proteases , oxygenase , ribulose , pyruvate carboxylase , proteolysis , chemistry , chloroplast , photosynthesis , biology , enzyme , gene
Trypsin‐catalysed cleavage of purified ribulose 1,5‐bisphosphate carboxylase/oxygenase (Rubisco) and the resultant irreversible loss of carboxylase activity were prevented by prior incubation with the naturally occurring nocturnal Rubisco inhibitor 2′‐carboxy‐ d ‐arabitinol 1‐phosphate (CA1P), as well as with ribulose 1,5‐bisphosphate (RuBP), Mg 2+ and CO 2 . CA1P also protected Rubisco from loss of activity caused by carboxypeptidase A. When similar experiments were carried out using soluble chloroplast proteases, CA1P was again able to protect Rubisco against proteolytic degradation and the consequent irreversible loss of catalytic activity. Thus, CA1P prevents the proteolytic breakdown of Rubisco by endogenous and exogenous proteases. In this way, CA1P may affect the amounts of Rubisco protein available for photosynthetic CO 2 assimilation. Rubisco turnover (in the presence of RuBP, Mg 2+ and CO 2 ) may confer similar protection against proteases in the light.