Study of the effect of accelerated electrons on the structural characteristics of the bovine serum albumin using liquid chromatography-mass spectrometry and high-resolution tandem mass spectrometry

Abstract

A method for quantification of the dose effect of ionizing radiation on the structural characteristics of bovine serum albumin (BSA) in aqueous solution through identification of unique peptides of protein domain structures using high-resolution liquid chromatography-mass spectrometry is proposed. BSA with the initial concentration of 500 mg/liter in a physiological solution was exposed to irradiation at a dose rate of 18. 5 Gy/sec using an accelerated electron beam with the maximum energy of 1 MeV at an average beam current of 1 uA. The absorbed dose in the sample volume was estimated using a Fricke (ferrous sulphate) dosimeter. After irradiation of BSA solution at 0.3, 0.6,1.8, and 20 kGy we analyzed the structural integrity of the protein native form and then quantified the content. For this, masses more than 30 kDa were removed using centrifugation. Then BSA was subjected to enzymatic hydrolysis with the addition of trypsin solution, and the resulting peptides with a mass of more than 10 kDa were repeatedly removed. The resultant samples were then examined using liquid chromatography mass spectrometry (LC-MS) and high-resolution tandem mass spectrometry (HRMS-MS/MS). The content of intact protein molecules was assessed by determining the concentrations of unique peptides corresponding to each of the three domains into which the amino acid sequence of BSA was divided. Using the developed methodology, a change in the natural conformation of bovine serum albumin (denaturation) in water samples induced by ionizing radiation at a dose ranging from 0.3 to 20 kGy was revealed on average in 71% of protein molecules exposed to doses up to 1 kGy in 79% of molecules exposed to doses of 4 kGy and in 99 % to 100% of molecules exposed to doses of 8 and 20 kGy.