The vacuum ultraviolet circular dichroism (VUVCD) spectra of 15 globular proteins (myoglobin, hemoglobin, human serum albumin, cytochrome c, peroxidase, α-lactalbumin, lysozyme, ovalbumin, ribonuclease A, β-lactoglobulin, pepsin, trypsinogen, α-chymotrypsinogen, soybean trypsin inhibitor, and concanavalin A) were measured in aqueous solutions at 25°C in the wavelength region from 260 to 160 nm under a high vacuum, using a synchrotron-radiation VUVCD spectrophotometer. The VUVCD spectra below 190 nm revealed some characteristic bands corresponding to different secondary structures. The contents of α-helices, β-strands, turns, and unordered structures were estimated using the SELCON3 program with VUVCD spectra data on the 15 proteins. Prediction of the secondary-structure contents was greatly improved by extending the circular dichroism spectra to 165 nm. The numbers of α-helix and β-strand segments calculated from the distorted α-helix and β-strand contents did not differ greatly from those obtained from X-ray crystal structures. These results demonstrate that synchrotron-radiation VUVCD spectroscopy is a powerful tool for analyzing the secondary structures of proteins.

This article cannot obtain the latest cited-by information.