Serum albumin optical rotatory dispersion

ACS = anunonium (-l-)-DlO-camphorsulfonate BSA = bovine serum albumin CD = circular dichroism CT = charge transfer hCCS = human copper chaperone for superoxide dismutase hSCAN = human soluble calcium-activated nucleotidase-1 LMCT = ligand-to-metal charge transfer METP = miniaturized electron transfer protein MECT = metal-ligand charge transfer ORD = optical rotatory dispersion SODs = superoxide dismutases tCCS = tomato copper chaperone for superoxide dismutase UTP = uracil triphosphate. 

The initial decrease in optical rotation found in aqueous solutions of /3-lactoglobulin and ovalbumin is not, however, sufficient to differentiate globular proteins from simpler synthetic polypeptides in their transition behavior, for neither ribonuclease nor human serum albumin appear to exhibit it. The specific rotation of ribonuclease in water-2-chloroethanol mixtures becomes steadily less levorotatory as the proportion of nonpolar solvent increases (Weber and Tanford, 1959). In the case of human serum albumin Bresler (1958) and Bresler el al. (1959) find that only progre.ssive increases in specific rotation occur as the concentration of 2-chloroethanol is increased and that this change is accompanied by a steady rise in viscosity and the corresponding axial ratios characteristic of the formation of rodlike particles. If these proteins do have some initial helical content in water, as can be argued from their optical rotatory dispersion, then it appears that hydrophobic forces are not required for the stability of these regions. 

J9. Jirgensons, B., Optical-rotatory-dispersion studies on serum albumin of cancer patients. Cancer 10, 1086-1091 (1957). 

Unfortunately, many of the observations of Cotton effects in proteins must, in the absence of spectrophotometric details, be viewed with some skepticism. This caution arises from the ease with which rotatory artifacts may be produced in regions of high absorbance. Winkler and Markus (1959) found that the unusual rotatory dispersions observed in azo-dye complexes of human serum albumin between 550 and 750 m/i (Markus and Karush, 1958) were attributable to stray light polarized by reflection within the cell housing and which the opacity of dye solutions allowed to predominate. It has more recently been found (Urnes et al., 1961b) that stray light in the optical path can give rise to artifacts at absorption bands that simulate... 

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