Structural properties of polyC–scleroglucan complexes

✍ Scribed by Marit Sletmoen; Bjørn T. Stokke

• Book ID: 101720257
• Publisher: Wiley (John Wiley & Sons)
• Year: 2005
• Tongue: English
• Weight: 304 KB
• Volume: 79
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.20340

✦ Synopsis

Abstract

Successive changes of solvent conditions can be used to dissociate and reassociate the triple‐helical structure of (1,3)‐β‐D‐glucans. Ultramicroscopic techniques have revealed a blend of circular and other structures following renaturation. When this solvent exchange process is carried out in the presence of certain polynucleotides, the process creates a novel macromolecular complex. Here, we use size exclusion chromatography (SEC) to study such (1,3)‐β‐D‐glucan‐polynucleotide complexes. Online multiangle laser‐light scattering (MALLS) and refractive index (RI) detectors allowed determination of molecular weight and radius of gyration of the molecules. An ultraviolet (UV) detector allowed specific detection of the polynucleotide. The poly‐cytidylic acid (polyC) shifted to coelution with the linear fraction of the scleroglucan following the renaturation of polyC–scleroglucan blends, indicating that polyC is incorporated in linear, but not in circular, structures of scleroglucan. This conclusion was consistent with AFM topographs that revealed a decreased fraction of circular structures upon addition of polyC during the renaturation process. The combined information about radius of gyration (R~g~) and molecular weight (M~w~) allowed us to conclude that the polyC–scleroglucan complexes are more dense and have a higher persistence length than linear scleroglucan triple helixes. The experimentally determined mass per unit length was used as a basis for elucidating possible molecular arrangements within the polyC–scleroglucan complex. © 2005 Wiley Periodicals, Inc. Biopolymers 79: 115–127, 2005

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