1. What is Enzyme Activity?

Enzyme activity is a measure of the catalytic ability of an enzyme, typically expressed as the amount of substrate converted per unit time under specified conditions. The unit U/mL represents micromoles of substrate converted per minute per milliliter of solution.

2. How Does the Calculator Work?

The calculator uses the enzyme activity equation:

Where:

• \( \Delta A \) — Change in absorbance (dimensionless)
• \( \varepsilon \) — Molar extinction coefficient (M^-1cm^-1)
• \( t \) — Reaction time (minutes)
• \( volume \) — Reaction volume (milliliters)

Explanation: The equation converts absorbance changes into enzyme activity units by accounting for the molar absorptivity of the product, reaction duration, and reaction volume.

3. Importance of Enzyme Activity Measurement

Details: Measuring enzyme activity is essential for enzyme characterization, quality control in enzyme production, clinical diagnostics, and biochemical research.

4. Using the Calculator

Tips: Enter all values in the specified units. Ensure the path length is 1 cm (or correct your extinction coefficient accordingly). Measurements should be made in the linear range of the assay.

5. Frequently Asked Questions (FAQ)

Q1: What if my path length isn't 1 cm?
A: Adjust your extinction coefficient by multiplying it by your path length in cm before entering it into the calculator.

Q2: What are typical units for enzyme activity?
A: Most commonly U/mL (μmol/min/mL) or U/mg (μmol/min/mg) for specific activity.

Q3: How do I determine the extinction coefficient?
A: The extinction coefficient is a property of the product being measured and can be found in literature or determined experimentally.

Q4: What affects absorbance measurements?
A: Temperature, pH, wavelength accuracy, and sample turbidity can all affect absorbance readings.

Q5: What is a good ΔA range for accurate measurements?
A: Typically 0.1-1.0 absorbance units, within the linear range of your instrument and assay.