Which enzyme of glycolysis is also called as pacemaker enzyme ?

Options

A. Hexokinase
B. Enolase
C. Phosphofructokinase
D. Pyruvate kinase

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the enzyme in glycolysis that is referred to as the "pacemaker enzyme."

2. **Identifying the Options**: The options provided are:
- A) Hexokinase
- B) Anolase
- C) Phosphofructokinase
- D) Pyruvate kinase

3. **Defining a Pacemaker Enzyme**: A pacemaker enzyme is one that plays a crucial role in regulating the rate of a metabolic pathway, similar to how a pacemaker regulates the heartbeat in an organism.

4. **Analyzing Each Option**:
- **Hexokinase**: This enzyme catalyzes the phosphorylation of glucose to glucose-6-phosphate but is not the main regulatory step in glycolysis.
- **Anolase**: This enzyme is involved in the conversion of 2-phosphoglycerate to phosphoenolpyruvate but does not serve as a key regulatory point.
- **Phosphofructokinase (PFK)**: This enzyme catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate and is known to be a major regulatory point in glycolysis.
- **Pyruvate kinase**: This enzyme catalyzes the conversion of phosphoenolpyruvate to pyruvate but is not considered the pacemaker enzyme.

5. **Identifying the Correct Answer**: Based on the analysis, phosphofructokinase (PFK) is the enzyme that is referred to as the pacemaker enzyme in glycolysis.

6. **Justifying the Answer**:
- **Regulatory Role**: PFK is a key regulatory enzyme that allows the cell to control the rate of glycolysis based on its energy needs.
- **Committed Step**: The reaction catalyzed by PFK is a committed step in glycolysis, meaning that once this step is taken, the pathway will proceed to completion.
- **Rate Limiting Step**: PFK is considered a rate-limiting step in glycolysis, meaning its activity determines the overall rate of the glycolytic pathway.

7. **Final Answer**: The enzyme of glycolysis that is also called the pacemaker enzyme is **Phosphofructokinase (PFK)**.

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