title: Degradation of insoluble bovine collagen and human dentine collagen pretreated in vitro with lactic acid, pH 4.0 and 5.5.
abstract: The purpose of the study was to test the hypothesis that both insoluble pure type I collagen from bovine Achilles tendon and dentine collagen in root dentine powder from human teeth required acid pretreatment for subsequent degradation by trypsin, a non-specific protease. Pure type I collagen or dentine powder was treated with lactic acid, at pH 4 or 5.5, or distilled, deionized water (pH 7) as a negative control. After incubation at 37 degrees C for 24 h, extracts of pure type I collagen solutions were analysed for soluble collagen with the hydroxyproline assay. Extracts of dentine powder solution were analysed for Ca2+, total protein, final pH, and hydroxyproline. Residual, undegraded pellets were washed and then treated with trypsin or collagenase. After 24 h of incubation, the soluble fractions from the enzyme-treated pure type I collagen and dentine powder solutions were analysed for hydroxyproline. Results showed that almost no pure type I collagen was degraded during acid pretreatment. Trypsin degraded significantly more pure type I collagen in the pH 4-treated group than in the other groups. Collagenase degraded about 70% of the pure type I collagen irrespective of acid pretreatment. While acid pretreatment at pH 4 did not degrade dentine collagen, data from Ca2+ analyses and collagen breakdown by trypsin suggested that pretreatment at pH 4 demineralized and denatured dentine collagen so that the collagen could be subsequently degraded by enzymes. After pretreatment at pH 4, about 27 and 57% of the dentine collagen was degraded by trypsin and collagenase, respectively, in contrast to minimal degradation of non-acid-treated dentine collagen by the same enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Oral Biology, School of Dentistry, Indiana University, Indianapolis 46202, USA.
authors.forename: S Z
authors.initials: SZ
authors.lastname: Dung
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: A J
authors.initials: AJ
authors.lastname: Dunipace
authors.forename: G K
authors.initials: GK
authors.lastname: Stookey
mesh_terms: D000125:Achilles Tendon / Q000737:chemistry; D000818:Animals; D002118:Calcium / Q000032:analysis; D002417:Cattle; D003094:Collagen / Q000032:analysis / Q000737:chemistry*; D017364:Collagenases / Q000737:chemistry; D003804:Dentin / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006909:Hydroxyproline / Q000032:analysis; D007773:Lactates / Q000737:chemistry*; D019344:Lactic Acid; D010750:Phosphoproteins / Q000032:analysis; D011506:Proteins / Q000032:analysis; D012995:Solubility; D014357:Trypsin / Q000737:chemistry
chemical_list: D007773:Lactates; D010750:Phosphoproteins; D011506:Proteins; C017630:phosphophoryn; D019344:Lactic Acid; D003094:Collagen; D014357:Trypsin; D017364:Collagenases; D006909:Hydroxyproline; D002118:Calcium