| Comments |
The biochemistry of all terrestrial life depends upon energy from oxidation processes. The end product of metabolic pathways from carbon-based life is carbon dioxide, which is released into the atmosphere. To complete the carbon cycle, that carbon dioxide must be consumed in the food chain. The only enzyme known to break down carbon dioxide is Ribulose-1,5-Bisphosphate carboxylase, or rubisco. Rubisco represents the beginning of the food chain. In some bacteria, rubisco is composed of two identical subunits. In higher photosynthetic organisms, the enzyme is a 16-mer composed of two different subunits, a small subunit and the catalytically active large subunit. 65kDa refers to one large and one small subunit. "A 'perfect' catalyst should not only transform its subtrates as fast as they diffuse into the active site
but also represent a minimum investment of resources. For an enzyme, this means that its molecular
weight should be as small as possible. The relationship between the molecular size of an enzyme and
its catalytic prowess is not well understood. Rubisco's molecular weight per active site (approximately
65 000) is, perhaps, a little larger than the average of most enzymes but not excessively so. So Rubisco
rates relatively well on this subsidiary performance index." See BNID 105006 |