Question

(a) What are the names of the enzymes that carry out the following reactions, and what are their EC numbers based on systematic classification? (4 marks) (i) Tyrosine + a-ketoglutarate D p-Hydroxyphenylpyruvate + Glutamate Glucose + ATP → Glucose-6-phosphate + ADP (iii) Succinate + CoA +GTP D Succinyl-CoA + GDP + Pi (iv) Glutamine + H₂O → Glutamate + NH4+ The enzyme that carries out the reaction Tyrosine + a-ketoglutarate D p-Hydroxyphenylpyruvate + Glutamate is not solely composed of protein, there is an accessory organic molecule at the active site. What is this name of this molecule, and what is its function in the mechanism of the enzyme?(3 marks) (c) Briefly describe three mechanisms that contribute to the decrease of activation(3 marks)energy at an enzymes active site. (d) In developing their mathematical model for invertase, Michaelis and Mentenmade a number of assumptions to develop the model upon which their equation to describe enzyme kinetics is based. Explain what is meant by the'steady-state' assumption.(2 marks) (e) An enzyme that catalyses the conversion of molecule A into molecule B with aKm value of 2.4mM for molecule A and a keat value of 54 s-¹ (i)At what concentration of molecule A would the enzyme operate at 25% of the maximum rate?(2 marks) (ii)Determine the fraction of Vmax that is achieved when the [A] is equal to each-of the following multiples of Km: 0.33.Km, 5.Km, 40.Km and 100.Km (give values to 2d.p.).(3 marks) (iii)If the rate of reaction observed at 1.2mM A is 4.1 x 10-7 moles/L/min, what is the enzyme concentration in the reaction? Express your answer in nM.(3 marks)

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