Question

Bovine serum albumin has a MW of 66296 and 582 residues including 19 tyr and 2 trp. Predict an epsilon value at 280 nm.

How do I go about solving this please? You do not have to provide me the answer as I need to be able to do this on my own... but I don't know HOW to get the answer. What do I multiply/divide/etc?

Answer 1

Epsilon value of the protein can be calculated easily if we know the how many tyrosines, tryptophans and cysteines are present in the protein.

For calculating Epsilon value we need to do following calculation

number of Trp residues × 5,690 + number of Tyr residues × 1,280 + number of Cys residues × 120

In case of BSA epsilon value will be = 2*5690 + 19*1280 =

11380 + 24320

= 38700

unit of absorbency can be calculated by using Beer-Lambert law

A= Cl

here A = absorbance. It has no unit because its a ratio

C= concentration of protein. its unit is M or molar

l = path length its unit is cm

SO unit of = M^-1 cm^-1

for BSA = 38700M-1 cm-1