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Spectral contribution of the individual tryptophan of αB‐crystallin: A study by site‐directed mutagenesis
Author(s) -
Liang Jack JN.,
Sun TianXiao,
Akhtar Nila J.
Publication year - 1999
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.8.12.2761
Subject(s) - tryptophan , circular dichroism , chemistry , fluorescence , mutagenesis , crystallin , site directed mutagenesis , mutant , near ultraviolet , biophysics , stereochemistry , crystallography , biochemistry , biology , amino acid , optics , physics , gene
There are two tryptophan residues in the lens αB‐crystallin, Trp9 and Trp60. We prepared two Trp → Phe substituted mutants, W9F and W60F, for use in a spectroscopic study. The two tryptophan residues contribute to Trp fluorescence and near‐ultraviolet circular dichroism (UV CD) differently. The major difference in the near‐UV CD is the contribution of 1 L a of Trp: it is positive in W60F but becomes negative in W9F. Further analysis of the near‐UV CD shows an increased intensity in the region of 270–280 nm for W60F, suggesting that the Tyr48 is affected by the W60F mutation. It appears that Trp60 is located in a more rigid environment than Trp9, which agrees with a recent structural model in which Trp60 is in a β‐strand.