[Assignment of a component of serine proteinase fluorescence spectrum to a cluster of tryptophan residues].
The two log-normal spectral components in, alpha-chymotrypsin, trypsinogen and beta-trypsin fluorescence and the single component of chymotrypsinogen A emission were analyzed using characteristics of microenvironment of atoms of indolic fluorophores of individual tryptophan residues in the three-dimensional structures of the proteins. Tryptophan residues (eight ones in chymotrypsinogen A and alpha-chymotrypsin and four ones in trypsinogen and beta-trypsin) in these homologous proteins form three clusters with resonance excitation energy exchange between fluorophores within each of them. In all the proteins, Trp51 and 141 determine the shorter-wavelength spectral components (ca. 330 nm) and Trp215 and 237 emit as longer-wavelength ones (ca. 340 nm). Excited states of fluorophores of Trp27, 29, 207 (cluster A) and 172 (in cluster B) are deactivated by the near disulfide bonds. The longer-wavelength component is quenched in chymotrypsinogen emission due probably to the formation of an electron trap including Asn91 amide and several water molecules. The contribution of longer-wavelength component in trypsin spectrum increases comparing with that of trypsinogen due to some little changes in localization and a huge rise of mobility of Met180 sulfur atom nearly Trp215 in trypsin.
Reshetniak
Ia K
IaK
Burshteĭn
E A
EA
D004220:Disulfides / Q000737:chemistry; D012697:Serine Endopeptidases / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D014364:Tryptophan / Q000737:chemistry*
D004220:Disulfides; D014364:Tryptophan; D012697:Serine Endopeptidases