Temperature influence on the secondary structure of avidin and avidin-biotin complex: A vibrational circular dichroism study

Citation
F. Wang et Pl. Polavarapu, Temperature influence on the secondary structure of avidin and avidin-biotin complex: A vibrational circular dichroism study, J PHYS CH B, 105(32), 2001, pp. 7857-7864
Citations number
18
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHYSICAL CHEMISTRY B
ISSN journal
1520-6106 → ACNP
Volume
105
Issue
32
Year of publication
2001
Pages
7857 - 7864
Database
ISI
SICI code
1520-6106(20010816)105:32<7857:TIOTSS>2.0.ZU;2-T
Abstract
Vibrational absorption and vibrational circular dichroism spectra of avidin with and without d-biotin in phosphate buffer were recorded in the amide I ' (1800-1600 cm(-1)) region as a function of temperature. The differences in the unfolding pathway of avidin in the presence and absence of biotin we re examined using the curve-fitting results of absorption spectra, and the variable-temperature absorption and VCD spectra. This study reveals, contra ry to previous spectroscopic studies, but in agreement with X-ray structura l studies, that avidin contains beta -sheet structures with turns and bends , but does not contain a-helical structure. Also a cooperative structural t ransition leading to formation of aggregated antiparallel beta -strands, wi th increasing temperature, has been inferred. In avidin-biotin complex, how ever, some reversible unfolding of beta -sheet structure is noted but a coo perative structural transition has not been noted with increase in temperat ure. Two-dimensional (2D)-VCD correlation spectroscopy has also been used t o analyze the sequence of events in structural unfolding of avidin.