Khan S, Andralojc P J, Lea P J, Parry M A
Department of Biochemistry, IACR-Rothamsted, Harpenden, Hertfordshire, UK.
Eur J Biochem. 1999 Dec;266(3):840-7. doi: 10.1046/j.1432-1327.1999.00913.x.
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), Mg2+ and CO2. 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 CO2 assimilation. Rubisco turnover (in the presence of RuBP, Mg2+ and CO2) may confer similar protection against proteases in the light.
通过与天然存在的夜间型核酮糖-1,5-二磷酸羧化酶/加氧酶（Rubisco）抑制剂2'-羧基-D-阿拉伯糖醇1-磷酸（CA1P）以及核酮糖-1,5-二磷酸（RuBP）、Mg2+和CO2预先孵育，可防止胰蛋白酶催化纯化的核酮糖-1,5-二磷酸羧化酶/加氧酶（Rubisco）的裂解以及由此产生的羧化酶活性的不可逆丧失。CA1P还能保护Rubisco免受羧肽酶A导致的活性丧失。当使用可溶性叶绿体蛋白酶进行类似实验时，CA1P再次能够保护Rubisco免受蛋白水解降解以及随之而来的催化活性的不可逆丧失。因此，CA1P可防止内源性和外源性蛋白酶对Rubisco的蛋白水解分解。通过这种方式，CA1P可能会影响可用于光合CO2同化的Rubisco蛋白的量。在光照条件下，Rubisco周转（在RuBP、Mg2+和CO2存在的情况下）可能对蛋白酶具有类似的保护作用。
