SECONDARY STRUCTURE OF ALBUMIN ACQUIRED RAPIDLY BY MODIFIED CONVENTIONAL ATR-FTIR IS COMPARABLE TO CD SPECTRAL DATA

Protein secondary structure in the bulk aqueous state is technically challenging to obtain by direct FTIR measurement. A new convenient technique for secondary structure analysis using ATR-FTIR spectroscopy is described in which the aqueous conformation of albumin appears to be preserved. A disaccharide, cellobiose, is lyophilized onto the zinc selenide ATR specimen holder, producing a glassy film onto which the protein is subsequently layered and dried. Curve fitting analysis of the deconvoluted spectra obtained in the presence of the cellobiose film showed that bovine serum albumin contained 64 (+/-0.5%) alpha-helix, a value similar to published ''aqueous-simulated CD'' values. The simple and rapid technique of coating an ATR crystal with cellobiose for FTIR spectroscopy may be useful for studying the aqueous conformation of other surface interactive proteins and may present several advantages over more cumbersome approaches. (C) 1994 Academic Press, Inc.