Fluorescence properties of glutamine-binding protein from Escherichia coli and its complex with glutamine.
In this work, the fluorescence of glutamine-binding protein (GlnBP) and its complex with glutamine (GlnBP/Gln) in native and unfolded forms was studied. The experimental data were interpreted on the basis of the results of the analysis of Trp and Tyr microenvironments taking into the account the data for GlnBP mutated forms Trp32Phe(Tyr) and Trp220Phe(Tyr), which have been obtained by Axelsen et al. (Biophys. J. 1991, 60, 650-659). This allowed us to explain the negligible contribution of Tyr residues to the bulk fluorescence of the native protein, the similarity of the fluorescence characteristics of GlnBP and GlnBP/Gln, and the uncommon effect of the excess of the fluorescence intensity at 365 nm (Trp emission) upon excitation at 297 nm respect to the excitation at 280 nm. The last effect is explained by the spectral dependence of the Trp 32 and Trp 220 contributions to the protein absorption. The protein Trp fluorescence dependence on the excitation wavelength must be taken into account for the evaluation of the Tyr residues contribution to the bulk fluorescence of protein, and in principle, it also may be used for the development of an approach for the decomposition of a multicomponent protein fluorescence spectrum.
Kuznetsova
Irina M
IM
Institute of Cytology, Russian Academy of Science, 194064 St. Petersburg, Russia.
Stepanenko
Olga V
OV
Turoverov
Konstantin K
KK
Staiano
Maria
M
Scognamiglio
Viviana
V
Rossi
Mose'
M
D'Auria
Sabato
S
D002352:Carrier Proteins / Q000737:chemistry*; D004926:Escherichia coli / Q000737:chemistry*; D005453:Fluorescence; D005973:Glutamine / Q000737:chemistry*; D008958:Models, Molecular; D011487:Protein Conformation
D002352:Carrier Proteins; C037853:glutamine transport proteins; D005973:Glutamine