Question

QUESTION THREE (20 MARKS) The enzyme malate dehydrogenase (MDIH) catalyses the following reaction: Malate +NADoxaloacetate + NADH a) Which of the six major groups of enzymes (oxidoreductases, transferases, hydrolases s] l lyases, isomerases and ligases) does MDH belong to? Explain your answer. 2 mark b) What equipment would you use to assay this reaction; what would you measure and why 14 Marks] c) Malate dehydrogenase from pig liver mitochondria has a K M of 0.3 mM malate. Sketch a graph of the reaction rate (V) vs malate concentration for this enzyme assuming Michalis- Menten kinetics. Label the position of 0.3 mM malate on your graph: also indicate the position of Vma [4 Marks] d) In your new job as a laboratory technician you have been asked to make up I ml. of a solution containing 100 U MDH. Information on the bottle of enzyme concentrate indicates that the specific activity of the enzyme is 450 U/mg protein and the concentration of protein is 100 mg/mL. What volume of MDIH concentrate will you use? 14 marks] Show all working. Demonstrate your understanding of enzymes by choosing a variable other than [S] that may affect the reaction rate of an enzyme-catalysed reaction. Explain the effect of your chosen variable on enzyme activity/reaction rate e) [6 marks]

Answer 1

thi dan MDM b that en ho 2. km = 0.3 mM

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