title: The aggregation behavior of native collagen in dilute solution studied by intrinsic fluorescence and external probing.
abstract: The aggregation behavior of type I collagen in acid solutions with the concentrations covering a range of 0.06-1.50mg/mL was studied utilizing both of the fluorescence resonance energy transfer (FRET) between the phenylalanine and tyrosine residues and the external probing of 1,8-anilinonaphthalene sulfonate (ANS). FRET at 0.30 mg/mL showed the distance among collagen monomers was within 10nm without the obvious aggregates formed. The predominance of tyrosine fluorescence in FRET in the range of 0.45-0.75 mg/mL identified the existence of collagen aggregates companied with the formation of hydrophobic microdomains revealed by the change of the fluorescence of ANS. The blue-shift of tyrosine fluorescence from 303 to 293 nm for 0.90-1.50mg/mL dedicated the formation of high order aggregates. The results from the two-phase diagrams of the intrinsic fluorescence for the guanidine hydrochloride-induced unfolding of collagen confirmed these conclusions. By the two-dimensional correlation analysis for the intrinsic fluorescence of collagen solutions of 0.45, 0.75 and 1.05 mg/mL, the probable characteristic fluorescence peaks for the interactions of proline-aromatic (CH∼π) among the collagen molecules were found at 298 and 316 nm.
authors.affiliation: National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Wu
authors.forename: Wentao
authors.initials: W
authors.lastname: Liu
authors.forename: Guoying
authors.initials: G
authors.lastname: Li
mesh_terms: D000817:Anilino Naphthalenesulfonates / Q000737:chemistry; D000818:Animals; D002417:Cattle; D024042:Collagen Type I / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer; D019791:Guanidine / Q000737:chemistry; D010649:Phenylalanine / Q000737:chemistry; D058767:Protein Unfolding; D012996:Solutions; D014443:Tyrosine / Q000737:chemistry
chemical_list: D000817:Anilino Naphthalenesulfonates; D024042:Collagen Type I; D012996:Solutions; D014443:Tyrosine; D010649:Phenylalanine; D019791:Guanidine