Type-I trimer and type-I collagen in neutral-salt-soluble lathyritic-rat dentine

Triple-helical collagen molecules have been obtained from EDTA-demineralized lathyritic rat incisors by neutral buffer extraction. Component alpha chains, isolated by sequential ion-exchange and gel-filtration chromatography, were shown to be alpha1 I and alpha2 chains by cyanogen bromide peptide analysis. The alpha1 I:alpha2 chain ratio was approximately 3:1, which is greater than expected for type I collagen. The excess of alpha1 I chains over that required for type I collagen was due to the presence of type I trimer molecules. Fractional salt precipitation separated type I collagen from type I trimer. It is not known at present if type I trimer synthesis also occurs in normal rat tissues.