Enzymes with two sites are called

Options

A. apoenzyme
B. allosteric enzyme
C. holoenzyme
D. conjugate enzyme.

Explanation

To solve the question "Enzymes with two sites are called," we will analyze the provided options step by step.

### Step 1: Understand the Options
We have four options to consider:
1. Apoenzyme
2. Allosteric enzyme
3. Holoenzyme
4. Conjugate enzyme

### Step 2: Analyze Each Option
- **Apoenzyme**: This refers to the protein part of an enzyme without its cofactor. It does not have two sites for binding, so this option is incorrect.

- **Allosteric enzyme**: These enzymes have two distinct sites: an active site where the substrate binds and an allosteric site where regulatory molecules can bind. This allows for the regulation of the enzyme's activity, making this option a strong candidate for the answer.

- **Holoenzyme**: This term describes the complete enzyme that includes the apoenzyme and its cofactor. It does not specifically refer to having two sites, so this option is also incorrect.

- **Conjugate enzyme**: This term refers to enzymes that have a prosthetic group attached. While they may have multiple components, it does not specifically indicate that they have two sites for binding, making this option incorrect as well.

### Step 3: Identify the Correct Answer
From the analysis, the only option that specifically refers to enzymes with two sites is the **Allosteric enzyme**. Therefore, the correct answer to the question is:

**Allosteric enzyme**

### Summary of the Solution
- The correct answer is **Allosteric enzyme**, as it is characterized by having two sites: an active site and an allosteric site.