Question

Succinylcholine is a fast-acting, short-duration muscle relaxant. Doctors use the chemical before inserting a tube into a patient's trachea. Immediately after administering succinylcholine, the patient experiences muscle paralysis and needs a respirator for the rest of the examination. Succinylcholine causes paralysis by competitively inhibiting acetylcholinesterase, a nervous system enzyme. However, serum cholinesterase hydrolyzes succinylcholine. Paralysis lasts for several minutes until serum cholinesterase hydrolyzes all the succinylcholine. As a safety measure, doctors measure serum cholinesterase activity before examinations that require succinylcholine. These measurements help the doctor determine the appropriate succinylcholine dosage. Normal serum cholinesterase has a KM of 1.4 mM and exhibits 80 units of activity per liter. Assume the typical succinylcholine dose is well below the concentration required to induce serum cholinesterase's maximal reaction velocity, Vmax What would happen to a patient with a mutated serum cholinesterase that has a KM of 10 mm, but an unchanged What would happen to a patient with a mutated serum cholinesterase that has 10 units of activity per liter? Vmax ? O Paralysis will last a shorter amount of time. O Paralysis will last a longer amount of time. O Paralysis will last the same amount of time. O Paralysis will last a longer amount of time. Paralysis will last the same amount of time. O Paralysis will last a shorter amount of time.

Answer 1

Q1 - Paralysis will last for a longer amount of time. When the km of the enzyme for a substrate increase , the affinity for the substrate decreases. Km is the concentration of substrate ( Succinyl choline ) to reach half maximal velocity. When the substrate concentration is high , the enzyme takes more time to hydrolyze all the Succinyl choline. There for Succinyl choline will compete with acetyl cholinesterase for a longer time making the paralysis last longer.

Q2 Paralysis last for a longer amount of time.

Since serum cholinesterase hydrolyses Succinyl choline and stops the paralysing action. If the activity of the enzyme decreases ,it affects the hydrolysis of the succinyl choline making the paralysis to last longer.