Comparative Biochemistry of Ribulose Bisphosphate Carboxylase in Higher Plants
The agronomically important aspects of the comparative biochemistry of RuBP carboxylase are locating a natural enzyme, creating a mutant enzyme, or identifying compounds which differentially alter the enzyme so as to allow CO2 to be fixed more efficiently or O2 to be fixed less efficiently. Two interrelated approaches can be pursued in trying to increase the agronomic efficiency of the enzyme at atmospheric CO2 concentration. (i) The specific activity of the enzyme could be increased by increasing the maximal velocity of the enzyme’s action with respect to both substrates. This will cause a proportional increase in both photosynthesis and photorespiration, but, because the rate of CO2 uptake by photosynthesis exceeds the rate of CO2 loss by photorespiration under natural conditions, net photosynthesis will increase, (ii) The ratio of oxygenase activity to carboxylase activity could be decreased, thereby increasing net photosynthesis by decreasing photorespiratory CO2 evolution.
KeywordsTall Fescue Sugar Phosphate Comparative Biochemistry Oxygenase Activity Agronomic Efficiency
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