ISSN:
1075-4261
Keywords:
transferrin
;
Raman
;
absorption
;
mutants
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Physics
Notes:
The resonance Raman (RR) data for a variety of transferrin samples were investigated to explore differences between the two active sites. The excitation wavelength dependence of the RR data in the low energy shift region (〈900 cm-1) for diferric transferrin (Fe2Tf) reveals extensive changes in the relative intensities for some of the peaks, indicating that the visible and near ultraviolet absorption of the Fe2Tf protein is composed of several distinct transitions. The identity of the low-energy vibrations was explored by comparison of the data from Fe2Tf, two different binding site mutants of the N-terminal site half transferrin molecule, Tf/2N, and Fe2Tf in which the normal binding site carbonate was replaced with C18O32-. The higher energy RR spectra of the various samples are quite similar, whereas the low-energy band patterns are strongly influenced by the mutations and isotopic substitution. Comparison of the RR data obtained from Fe2Tf, Tf/2N, and C-terminal monoferric transferrin reveals that the intensities and energies of the modes below 900 cm-1 are different for the two binding sites. This result helps reveal an isolated electronic transition for the N-terminal active site near 365 nm, where laser excitation yields selective enhancement of the low-energy N-terminal modes. © 1997 John Wiley & Sons, Inc. Biospectroscopy 3: 435-444, 1997
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
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