Near-ultraviolet circular dichroic activity of apomyoglobin: resolution of the individual tryptophanyl contributions by site-directed mutagenesis.

摘要: The individual tryptophanyl contributions to the near-ultraviolet circular dichroic activity of apomyoglobin in its native conformation have been resolved by studying recombinant proteins with single substitutions. Site-directed mutagenesis sperm whale was performed order obtain containing only Trp A-5 or A-12. These amino acid substitutions very little effect on overall globin fold as indicated comparing spectroscopic properties mutants those wild type protein. dichroism spectra two near ultraviolet were found be significantly different, both indole residues having significant but opposite sign. In particular, shows presence a main positive peak centered 294 – 295 nm marked shoulder at 285 nm, ascribed 1LBtransition. spectrum mutant protein A-12 large negative contribution minimum 283 and 293 nm. broadness exhibited suggests that it may originate mainly from 1LA transition.