Which of the following is not an attribute of enzymes-

Options

A. They are proteinaceous in nature
B. They speed up the rate of biochemical reactions
C. They are specific in nature
D. They are used up in reactions

Explanation

To determine which of the following is not an attribute of enzymes, let's analyze each option provided in the question:

1. **Enzymes are proteinaceous in nature.**
- Enzymes are primarily made of proteins. They are composed of amino acids and have a specific three-dimensional structure that is crucial for their function. This statement is true.

2. **Enzymes speed up the rate of biochemical reactions.**
- One of the main functions of enzymes is to act as catalysts that increase the rate of biochemical reactions by lowering the activation energy required for the reaction to occur. This statement is also true.

3. **Enzymes are specific in nature.**
- Enzymes are known for their specificity, meaning that each enzyme typically catalyzes a specific reaction or acts on a specific substrate. This is true as well.

4. **Enzymes are used up in reactions.**
- This statement is false. Enzymes are not consumed in the reactions they catalyze. They facilitate the reaction and can be reused multiple times without being altered in the process.

Based on this analysis, the correct answer to the question "Which of the following is not an attribute of enzymes?" is that enzymes are used up in reactions.

### Step-by-Step Solution:
1. Identify the nature of enzymes: Enzymes are proteinaceous.
2. Understand the role of enzymes: They speed up biochemical reactions.
3. Recognize the specificity of enzymes: They are specific to their substrates.
4. Clarify the misconception: Enzymes are not used up in reactions.

### Final Answer:
The statement that is not an attribute of enzymes is: "They are used up in reactions."