Near UV Protein CD

Synonyms
Protein aromatic circular dichroism; Protein side chain circular dichroism

Definition
Protein circular dichroism (CD) spectroscopy is usually separated into (1) far UV or backbone CD with data collected from ~190 to 250 nm and (2) near UV or aromatic CD with data collected from 250 to 300 nm. The aromatic chromophores of protein side chains (tryptophans, tyrosines, and phenyl alanines) are planar and so have no intrinsic CD. However, their location as part of an amino acid results in an induced CD signal in their transitions. This is further enhanced when they are located in the chiral environment of a peptide or protein. The signs and intensities of the CD signals induced into the achiral aromatic side chain transitions are dependent on their environment. It is a useful fingerprint of protein identity and conformation, but seldom leads to direct structural analysis. Disulfide bonds are often counted as honorary aromatic groups since their CD may be apparent between 250 and...