Enzyme inhibitions

What is competitive inhibition?

Inhibitor competes with substrates for binding to the active site.

How does an inhibitor affect Vmax in competitive inhibition?

Vmax remains the same; the slope of the Lineweaver-Burk plot increases.

What happens to Km in competitive inhibition?

Km increases; the inhibitor is similar in structure to the substrate.

What is uncompetitive inhibition?

Inhibitor binds only to the ES complex, not the free enzyme.

How does uncompetitive inhibition affect Vmax?

Vmax decreases as the concentration of inhibitor increases.

What is the effect of uncompetitive inhibition on Km?

Km decreases; the inhibitor distorts the active site.

What is mixed inhibition?

Inhibitor can bind to either the enzyme (E) or the enzyme-substrate complex (ES).

How does mixed inhibition affect Vmax?

Vmax decreases as the concentration of inhibitor increases.

What happens to Km in mixed inhibition?

Km increases; the ratio of Km/Vmax changes.

What is allosteric inhibition?

Inhibition that occurs when an inhibitor binds to a site other than the active site.

What is the role of end product inhibition?

End products control their own rate of production through negative feedback.

What are isoenzymes?

Different forms of an enzyme that catalyze the same reaction in different tissues.

How do isoenzymes differ?

They have slight variations in the amino acid sequences of their quaternary structure.

What is the significance of maintaining high inhibitor concentration in competitive inhibition?

It ensures effective inhibition by reducing the availability of free enzyme for substrate binding.

What is the effect of increasing inhibitor concentration on Vmax in uncompetitive inhibition?

Vmax is lowered, and the y-intercept of the Lineweaver-Burk plot increases.

What is the relationship between Km and Vmax in uncompetitive inhibition?

The ratio of Km/Vmax remains the same despite changes in both values.

Identify the type of inhibitor: 'Inhibition is not reversed with substrate.'

Noncompetitive inhibitor.

Identify the type of inhibitor: 'Increasing substrate reverses inhibition.'

Competitive inhibitor.

Identify the type of inhibitor: 'Binds to enzyme, not active site.'

Noncompetitive inhibitor.

Identify the type of inhibitor: 'Structure is similar to substrate.'

Competitive inhibitor.