The spectrophotometric assay for ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) was used to determine the rate of increase in Rubisco activity over time in the presence or absence of Rubisco activase. Polynomial approximations to the raw data were used to smooth out minor fluctuations in the spectrophotometer readings, and Rubisco activase activity was expressed as nanomoles of activ...

Transgenic tobacco (Nicofiana fabacum L. cv W38) plants with an antisense gene directed against the mRNA of ribulose-1,sbiphosphate carboxylase/oxygenase (Rubisco) activase grew more slowly than wild-type plants in a C0,-enriched atmosphere, but eventually attained the same height and number of leaves. Compared with the wild type, the anti-activase plants had reduced CO, assimilation rates, nor...

Global warming and the rise in atmospheric CO(2) will increase the operating temperature of leaves in coming decades, often well above the thermal optimum for photosynthesis. Presently, there is controversy over the limiting processes controlling photosynthesis at elevated temperature. Leading models propose that the reduction in photosynthesis at elevated temperature is a function of either de...

Ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) activase, a soluble chloroplast protein which promotes light-dependent rubisco activation, was partially purified from spinach chloroplasts by ion-exchange and gel-filtration fast protein liquid chromatography. The protein could also be isolated using rate zonal centrifugation in sucrose gradients followed by conventional ion-exchange on...

Rubisco is a very large, complex and one of the most abundant proteins in the world and comprises up to 50% of all soluble protein in plants. The activity of Rubisco, the enzyme that catalyzes CO2 assimilation in photosynthesis, is regulated by Rubisco activase (Rca). In the present study, we searched for hypothetical protein of Vitis vinifera which has putative Rubisco activase function. The A...

The enzyme-catalyzed activation of ribulosebisphosphate carboxylase/oxygenase (rubisco) was investigated in an illuminated reconstituted system containing thylakoid membranes, rubisco, ribulosebisphosphate (RuBP), MgCl(2), carbonic anhydrase, catalase, the artificial electron acceptor pyocyanine, and partially purified rubisco activase. Optimal conditions for light-induced rubisco activation we...

We review the current understanding of the temperature responses of C(3) and C(4) photosynthesis across thermal ranges that do not harm the photosynthetic apparatus. In C(3) species, photosynthesis is classically considered to be limited by the capacities of ribulose 1.5-bisphosphate carboxylase/oxygenase (Rubisco), ribulose bisphosphate (RuBP) regeneration or P(i) regeneration. Using both theo...

T enzyme Rubisco, short for ribulose1,5-bisphosphate carboxylaseyoxygenase, is the enzyme that incorporates CO2 into plants during photosynthesis. As it constitutes about 30% of the total protein in a plant leaf, Rubisco is probably the most abundant protein on earth and a major sink for plant nitrogen. Rubisco is widely accepted as the ultimate rate-limiting step in photosynthetic carbon fixat...

The rate of CO(2) fixation by ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) following addition of ribulose 1,5-bisphosphate (RuBP) to fully activated enzyme, declined with first-order kinetics, resulting in 50% loss of rubisco activity after 10 to 12 minutes. This in vitro decline in rubisco activity, termed fall-over, was prevented if purified rubisco activase protein and ATP were ...

We tested the hypothesis that light activation of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is inhibited by moderately elevated temperature through an effect on Rubisco activase. When cotton (Gossypium hirsutum L.) or wheat (Triticum aestivum L.) leaf tissue was exposed to increasing temperatures in the light, activation of Rubisco was inhibited above 35 and 30 degreesC, respect...