Option D: Consider the mechanism of the enzyme enolase as discussed in lecture (figure below): Mg2+ PO3^2- O H C-C-C-H H OH HO O H-N-H C Lys345 Glu211 Enolase 2-Phosphoglycerate bound to enzyme Mg2+ PO3^2- O H C=C-C-H OH HO O H-N+-H C Lys345 Glu211 Enolic intermediate HOH PO3^2- O O=C-C=C H H Phosphoenolpyruvate (a) There is a Mg2+ in the active site, which appears to be participating in the reaction. What type of catalysis is this? (b) What is one role of the Mg2+ -- what is it doing to help the enzyme to catalyze the reaction? Explain briefly. (c) Considering your answer to "b" above, what would be the effect on kcat OR the Km (as appropriate) if the Mg2+ was missing? (perhaps it was removed from solution by chelation). Explain your answer.
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(a) The presence of Mg2+ in the active site and its participation in the reaction indicates that this is an example of metal ion catalysis. Show more…
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