INVESTIGADORES
VIÑARTA Silvana Carolina
congresos y reuniones científicas
Título:
FRET-assisted conformational studies of b-glucan biopolymers with biological activity
Autor/es:
VIRGILI ALEMAN I.M.; VIÑARTA S.C. ; FIGUEROA L.I.C. ; FARIÑA J.I.
Lugar:
Chubut
Reunión:
Congreso; XLVI Reunión Anual Sociedad Argentina de Investigación Bioquímica (SAIB 2010); 2010
Institución organizadora:
Sociedad Argentina de Investigación Bioquímica
Resumen:
(1g3)-β-D-glucans such as Laminarin (Lam) are known to behave as immunopotentiators. Triple-helix is the prevailing conformation in aqueous solution and can be denatured with NaOH as single or partially opened-helices conformers. Which of these conformers is biologically most active or, if complete strands separation actually occurs is unclear. Fluorescence resonance energy transfer (FRET) spectroscopy represents an indirect method to characterize conformational changes of NaOH-treated Lam. FRET phenomenon occurs when a donor excitation energy is transferred to an acceptor over a short distance (10-80 Å). In this work, Lam was derivatized with 1-aminopyrene (AP) as donor (λem 450 nm), and fluorescein-5-isothyocyanate (FITC) as acceptor (λem 520 nm). The chain opening degree was assessed by treating double-labeled Lam (Lam-AP-FITC) with different concentrations of NaOH (0·10 ? 1·00 M). FRET results demonstrated that partially opened triple-helix rather than single-helix conformation would be formed upon NaOH treatment of Lam. Increasing degrees of strand opening were associated with increasing concentrations of NaOH. From 0·10 to 0·25 M, FRET showed a significant decrease, involving an actual separation between AP and FITC probes. A conformational change degree between closed triple-helix and partially opened-triple-helix would be more reliable than the complete strands separation.