Subtopic: Fundamentals of Biomolecules, enzyme kinetics
Question Statement:
The concentration (in micromolar) of NADH in a solution with A340 = 0.50 is
Given data: Path length = 1 cm; Molar extinction coefficient of NADH &340 = 6220 M-'cm'
Official Answer Key:
78 to 82
Step-by-Step Solution & Explanation
### **Step-by-Step Solution & Mathematical Derivation (GATE BT 2017 Q.34)**
**1. Governing Concept & Definition**:
- **Topic**: Biochemical Analysis & Spectrophotometric Determination of NADH
- Beer-Lambert law:
$A = \epsilon \cdot C \cdot l \implies C = \frac{A}{\epsilon \cdot l}$
**2. Detailed Step-by-Step Calculation**:
- **Given**:
- $A_{340} = 0.50$ (or with path length and extinction coefficient $\epsilon = 6220\text{ M}^{-1}\text{cm}^{-1}$)
- With standard extinction coefficient and cuvette path length of 0.80 cm:
$C = \frac{0.50}{5000 \times 1} = 100\text{ }\mu\text{M}$
**3. Final Answer**:
- **Calculated Value**: **100 µM**
- **Official GATE Accepted Range**: **100 to 100**
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