On Particular Regimens of Derivative UV-spectrophotometry for Comparative Analysis of Proteins

Abstract

Bovine serum albumin and two oxygen transport proteins, hemocyanin from the snail Achatina fulica and bovine hemoglobin, were used to define what regimens of derivative UV-spectrophotometry are most appropriate for using it as an express technique for nondestructive comparative analysis of native proteins preparations. It was found that the fourth derivatives of proteins absorption spectra make it possible to detect the individual bands of aromatic amino acids in a way optimal for solving certain practical problems. An algorithm for calculating the fourth derivatives was selected experimentally. To verify the approach, the fourth derivatives of the native proteins spectra were reconstructed by combining those of individual aromatic amino acids spectra in the range of 240–300 nm. To demonstrate the individual differences between proteins, it is proposed to use the correlation coefficients of the fourth derivatives of spectra in the range of 240–300 nm or in the wavelength range of tyrosine and tryptophan. Although this approach does not provide for estimating the exact contents of individual aromatic amino acids in proteins, it allows comparing different proteins between each other. The proposed approach makes it possible to obtain an individual spectral “portrait” of a protein, which distinguishes it from other proteins and is useful as a reference for further experimental work with it.