a Acetylcholinesterasehas the following kinetic characteristics: kcat- 25000 s k

Question

a Acetylcholinesterasehas the following kinetic characteristics: kcat- 25000 s kca Km 108 MT's 1 Why are these characteristics important for the physiological function of acetylcholinesterase? (Assume that 2x108 acetylcholine molecules are released into the synaptic cleft so that lacetylcholine] 0.5 mM, and that 105 acetylcholinesterase molecules are present at the scene.) I acetylcholinesterase N O HO water HO-C- Acetycholne CH CH, CH CH CH CH CH CH2OH +600 +40 +200 8 40 Resting potential Time (ms) Closed

Explanation / Answer

The acetylcholine is released into the cleft at a rate of 25000 s-1, if this is the case then it would take 8 mins for releasing the 2*10^5 molecules into the synaptic cleft. i.e, 2*10^5/25000 = 8

The acetylcholine activates calcium activated potassium channels through an increase in calcium causing a membrane hyperpolarization and hence the depolarization and repolarization range within certain time limit is essential for the optimal activity of the enzyme.

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