True about revesible non-competetive inhibitorsa) Lower Vmaxb) Lower Kmc) Not affect Kmd) Not affect Vmaxe) Affect both V max & Km

**Core Concept**
Reversible non-competitive inhibitors bind to an enzyme at a site other than the active site, decreasing the enzyme's maximum velocity without affecting the binding of the substrate. This type of inhibition is characterized by its ability to reduce the maximum rate of reaction.

**Why the Correct Answer is Right**
The correct answer is related to the effect of reversible non-competitive inhibitors on enzyme kinetics. These inhibitors decrease the **Vmax** of the enzyme-catalyzed reaction because they reduce the amount of active enzyme available to convert substrate to product. However, they do not change the **Km** of the enzyme for its substrate, which is a measure of the binding affinity of the enzyme for the substrate.

**Why Each Wrong Option is Incorrect**
**Option B:** This option is incorrect because reversible non-competitive inhibitors do not affect the **Km** of the enzyme.
**Option C:** This is incorrect because the **Km** remains unchanged in the presence of a reversible non-competitive inhibitor.
**Option D:** This option is incorrect because reversible non-competitive inhibitors do affect **Vmax**, reducing it.
**Option E:** This option is incorrect because reversible non-competitive inhibitors affect **Vmax** but not **Km**.

**Clinical Pearl / High-Yield Fact**
Reversible non-competitive inhibition is a key concept in pharmacology, especially when considering the effects of drugs on enzyme activity. Remembering that these inhibitors reduce **Vmax** without affecting **Km** is crucial for understanding their impact on biochemical pathways.

**Correct Answer:** A. Lower Vmax