Substrate and product are stable in any enzyme - catalysed reaction. The transitional states between the stable substrate and the product in the reaction are

Options

A. stable
B. unstable
C. metastable
D. of higher energy than both substrate and product

Answer

To solve the question regarding the transitional states in an enzyme-catalyzed reaction, we can follow these steps:

### Step 1: Understand the Reaction Dynamics
In an enzyme-catalyzed reaction, the substrate is converted into the product. The substrate is stable, and the product is also stable but at a lower energy level compared to the substrate.

**Hint:** Think about the energy levels of substrates and products in a reaction.

### Step 2: Identify the Role of Enzymes
Enzymes lower the activation energy required for the reaction to proceed. This means that the enzyme facilitates the transition from substrate to product by providing an alternative pathway with lower energy barriers.

**Hint:** Consider how enzymes influence the energy profile of a reaction.

### Step 3: Define Transitional States
Transitional states, also known as transition states, are temporary states that occur during the conversion of substrate to product. These states are characterized by a high energy level and are unstable.

**Hint:** Remember that transitional states are not stable; they are fleeting and represent points of maximum energy.

### Step 4: Recognize the Nature of Intermediates
During the reaction, the substrate may form various unstable intermediates or transitional states before finally converting into the stable product. These intermediates are crucial for the reaction pathway.

**Hint:** Think about how the reaction progresses through various unstable forms before reaching the final product.

### Step 5: Conclude with the Correct Answer
Based on the understanding of transitional states and their characteristics, the answer to the question is that the transitional states between the stable substrate and the product in the reaction are the unstable intermediates.

**Final Answer:** The transitional states are the unstable intermediates.