Question

You have been given a competitive inhibitor for which you do not know the structure. Knowing only that the mode of inhibition is competitive, you would not be surprised that it might look like

	a.	substrate
	b.	enzyme
	c.	transition state
	d.	enzyme-substrate complex
	e.	a or c
	f.	a or d
	g.	b or c

Answer 1

The Correct answer is option 'a' i.e. substrate. In competitive inhibition, the structure of competitive inhibitor closely resembles the structure of enzyme's substrate. There will be competition between the substrate and inhibitor to bind with the enzyme. At any moment, enzyme can bind with either one of them. Because of the similar structure of substrate and competitive inhibitor, competitive inhibitor can bind reversibly to the enzyme's active site and forms enzyme-inhibtor(EI) complex. EI complex is equivalent to Enzyme-substrate (ES) complex. In competitive inhibition, the effect of inhibitor can be reversed by increasing the substrate concentration.