The Limits For Life Define The Limits For Enzymes
There are natural constraints that limit enzyme concentrations between 10 nM and 10 μM. For signaling switches kcat’s are very low, at 10–2–10–5 s–1. For metabolic enzymes kcat’s must be ≥1 s–1, and are generally 10–3,000 s–1. It then follows that for metabolic enzymes Km values are generally limited to be between 1 μM and 1 mM. While increased Km values would enable much faster kcat’s, there is a clear need for enzymes to be sufficiently discriminating since so many have affinity constants below 100 μM.
KeywordsBinding Constant Glycolytic Enzyme Affinity Constant Triose Phosphate Isomerase Acceptor Substrate
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