The Circular Dichroism of Staphylococcal Enterotoxins A, B, and C.

摘要

The circular dichroism (CD) of staphylococcal enterotoxins A, B and C was measured. The CD of enterotoxins B and C were almost identical from 250-320 nm, but differed from the CD of enterotoxin A. The spectrum of enterotoxin A in this wavelength region contained the same bands with respect to both location and sign, but with significant differences in intensity. The CD spectra of enterotoxins B and C were also much more alike from 190-250 nm. Although all three enterotoxins had a major negative extremum at 215-218 nm, its magnitude was equal in enterotoxins B and C, but was substantially decreased in enterotoxin A. The secondary structure of the enterotoxins contained little alpha-helix as analyzed CD models. A secondary structure of enterotoxin B computed from a scheme based on a joint prediction histogram of five separate methods, placed 29 residues in alpha-helices, 71 in beta-pleated sheets, 88 in beta-turns and 55 in random coil.