Changes in the refractive index of a solution during proteolysis of bovine serum albumin with pepsin

Abstract

The protein refractive index was observed to increase by 8 · 10^–6 during proteolysis of bovine serum albumin (BSA, 4 mg/mL) with pepsin (2.2 mg/mL). It was believed earlier that the refractive index of a protein solution depends only on the protein concentration and amino-acid composition and remains unchanged during protein hydrolysis. An increase in the refractive index during proteolysis in solution was detected using an original laser interferometer with an improved sensitivity. The interferometer makes it possible to measure the difference in refractive index between solutions in two cells to an accuracy of approximately 6 · 10^–7.