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Conformational effects of nucleotide exchange in ras p21 proteins as studied by fluorescence spectroscopy
Author(s) -
Skelly Jane V.,
Suter David A.,
Kuroda Reiko,
Neidle Stephen,
Hancock John F.,
Drake Alex
Publication year - 1990
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(90)80170-n
Subject(s) - tryptophan , fluorescence , chemistry , circular dichroism , tyrosine , nucleotide , mutant , fluorescence spectroscopy , biophysics , crystallography , biochemistry , biology , amino acid , gene , physics , quantum mechanics
The intrinsic fluorescence properties of the oncogene protein p21 N‐ras , p21 H‐ras and one of its transforming mutants, p21 N‐ras (Va1112), have been investigated. A mutant containing a single tryptophan at position 28 in p21 H‐ras (Trp28) has been specifically engineered to provide a probe of protein conformation on nucleotide binding. The proteins produced essentially similar circular dichroism spectra typical of alpha/beta proteins. A decrease in the intensity of the fluorescence emission spectrum due to tyrosine occurred on GDP/GTP nucleotide exchange in the native and mutant proteins. Selective excitation of the single tryptophan in p21 produced a decrease in fluorescence intensity which was accompanied by a blue shift in the wavelength of maximum emission on nucleotide exchange. A reduction in the residual Mg 2+ ion concentration enhanced this effect.