# What is the extinction coefficient of NADH at 340 nm?

**What is the extinction coefficient for Nadph?**

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## What is the extinction coefficient of NADH at 340 nm?

6.22 l/mmol/cm

The molar extinction coefficient for NADH or NADPH at 340 nm is 6.22 l/mmol/cm, which, according to the Beer–Lambert law, means that a solution of 0.1 mM would have an optical density equal to 0.622 through a 1-cm light path.

**What is the extinction coefficient for Nadph?**

The extinction coefficient of NADPH is 6.22 mM-1 cm-1, which can be used to directly quantify the formation and at the end the total product formed during the reaction, assuming the concentration of substrate S is limited in solution and NADP+ is available in excess.

**How do you calculate molar absorptivity coefficient?**

Using algebra we can divide absorbance by the length and the concentration to get molar absorptivity on one side of the equation: ɛ = A/lc. We can now use this basic equation to calculate molar absorptivity for a given wavelength.

### What does the molar absorptivity coefficient tell you?

The molar attenuation coefficient or molar absorption coefficient is a measurement of how strongly a chemical species absorbs, and thereby attenuates, light at a given wavelength. It is an intrinsic property of the species.

**What are the units of the molar extinction coefficient?**

The SI units of ε are m2/mol, but in practice they are usually taken as M-1cm-1. The molar extinction coefficient is frequently used in spectroscopy to measure the concentration of a chemical in solution. Where: A is the amount of light absorbed by the sample for a particular wavelength.

**What is the extinction coefficient ε of NADH at the wavelength we monitor the absorbance at?**

NADH has an absorption band centered at 340 nm with an extinction coefficient of 6.22 x 103 cm-1M-1, while NAD+ has no absorbance at this wavelength.

## How is Nadph production measured?

The amount of NADP+ produced by the reaction is quantified by comparison to known concentrations of NADP+ standards. The NAD+ kinase activity is calculated by subtracting the amount of NADP+ produced by the reaction from the amount of NADP+ produced without the addition of the tissue lysate.

**How is Pathlength calculated?**

You can determine pathlength empirically: fill 3-4 replicate wells with the same volume of water as your samples. Measure absorbance at 900 nm (A900) and 977 nm (A977). Calculate means for A900 and A977 and determine your pathlength (cm) as (A977-A900)/0.18.

**How do you calculate wavelength from absorbance?**

This can be given as Ay = -log10(I/Io) where Ay is the absorbance of light with wavelength y and I/Io is the transmittance of the test material. Observe that absorbance is a pure number without units of measure. Absorbance is based on the ratio of two intensity measurements, so the resulting value has no units.

### How do you convert between %T and absorbance?

To convert a value from percent transmittance (%T) to absorbance, use the following equation: Absorbance = 2 – log(%T). For example to convert 56% T to absorbance calculate 2 – log(56) = 0.252 absorbance units.

**Is the molar absorption coefficient constant?**

Absorbance and Extinction Coefficients Beer’s Law states that molar absorptivity is constant (and the absorbance is proportional to concentration) for a given substance dissolved in a given solute and measured at a given wavelength.