Soluble collagen with high aldehyde content extracted from insoluble collagen with mercaptoethylamine

Effect of volatile thiol compounds on protein metabolism by human gingival fibroblasts

The levels of volatile sulphur compounds (VSC) in periodontal pockets and mouth air have been found to correlate with severity of the disease process. The purpose of this study was to examine the influence of hydrogen sulphide and methyl mercaptan on protein metabolism of human gingival fibroblasts. The incorporation of labelled amino acids into protein was used to evaluate effects on total protein content. Changes in collagenous protein concentration were monitored by release of radioactivity following collagenase digestion as well as direct analysis of hydroxyproline. Both thiols were found to reduce total protein synthesis, with mercaptan exerting a greater adverse effect. In cultures exposed to mercaptan, total protein was reduced by 35%. The changes in total protein were accompanied by a corresponding decrease in collagenase-digestible protein. Hydroxyproline analysis of CH3SH-exposed cultures confirmed the changes associated with collagenous proteins. It indicated that in comparison to the controls the CH3SH-exposed cultures had a 70% reduction in collagen which resulted from a combined effect of suppressed synthesis and increased rate of collagen degradation. The possibility of thiol reaction with collagen was determined using in vitro systems in which type I collagen was reacted with varying concentrations of [35S]-H2S. The carboxymethyl (CM) cellulose assays of resulting reaction mixtures indicate that [35S]-radioactivity was incorporated directly into alpha 1, alpha 2, beta 11, beta 12 peptide chains. Furthermore, upon exposure of collagen to elevated H2S concentrations, the H2S converted some of the acid-soluble collagen to a more soluble product which could be extracted in neutral salt and analyzed by CM-cellulose chromatography.(ABSTRACT TRUNCATED AT 250 WORDS)

Penicillamine and collagen metabolism

Penicillamine blocks the crosslinking of collagen in man and in all the animal species it has been tested in. At the standard dose in which it is used it binds to the aldehydes present in collagen and prevents them from forming crosslinks. It is more efficient in inhibiting the crosslinking of soft tissues, where the aldehydes are derived from lysine, and less effective in preventing crosslinking of bone, where the aldehydes involved are primarily those derived from hydroxylysine. At very high doses it can inhibit lysyloxidase activity by making Cu unavailable to the enzyme.

Differences in the collagen types synthesized by lapine articular chondrocytes in spinner and monolayer culture

In five different secondary monolayer cultures of rabbit articular chondrocytes, 72-89% of the the collagen synthesized was Type 1, as determined by alpha chain separation and CNBr-cleavage peptide analysis. When sister cells were transferred to spinner bottles after primary monolayer culture growth, 88% of the collagen formed in four separate experiments was Type II. A reversion to Type I collagen synthesis occurred when the spinner-cultured cells were returned to monolayer flasks. The change in the species of collagen depended on the suspension condition and not on the low Ca2+ content (0.33 mM) of the spinner medium. These findings parallel the switch to phenotypic glycosaminoglycan synthesis that also occurs when monolayer-cultured cells are transferred to spinner bottles. Whether this phenomenon arises through a genetic control mechanism rather than environmental selection for particular cohorts of cells has not yet been determined.

Characterization of the collagen synthesized by cultured cartilage cells

Cartilage cells from embryonic chick cartilage were grown in primary cultures. The cell layer was sequentially extracted with neutral saline, mercaptoethylamine and pepsin which revealed that these cells produced salt-soluble and salt-insoluble collagen. The alpha1- to alpha2-chain ratio was determined for the collagen extracted from the cultured cells and was found to be 13 to 1. Further analysis of the molecule was carried out by CNBr cleavage of the salt-extracted collagen and separation of resulting peptides by ion-exchange chromatography. It was shown that the cultured cartilage cells synthesize collagen of the type (alpha1[II])3.

Differences in collagen metabolism between normal and osteoarthritic human articular cartilage

Normal human articular cartilage synthesizes only one type of a chain, which exhibits the chromatographic behavior of the alpha(l)(II) chains described for chick and bovine cartilage. Osteoarthritic cartilage, on the other hand, synthesizes in addition a collagen containing alpha(2) chains and beta components. The different structural features of the two types of collagen may account for some of the functional defects of osteoarthritic cartilage.

Chemical changes associated with aging of collagen in vivo and in vitro

Collagen extracted from rat skin by neutral-salt solutions contains less aldehydes than the more insoluble collagen fractions. The concentration of aldehydes in collagen is directly related to its capacity to form stable cross-linked gels, which do not redissolve on cooling and become more insoluble in a variety of reagents. Whereas the absorption spectrum of neutral-salt-soluble collagen treated with N-methylbenzothiazolone hydrazone resembles that of acetaldehyde, the more insoluble collagen fractions show increasing amounts of a component that behaves like an alphabeta-unsaturated aldehyde. The ratio between alpha- and beta-sub-units present in a particular fraction of soluble collagen seems to be constant and independent of the age of the animal. Neutral-salt-soluble collagen, which has a low concentration of beta-components, will generate intramolecular bonds if gelled at 37 degrees . These intramolecular bonds seem to precede the formation of stable intermolecular cross-links, since these gels can redissolve when cooled to yield a soluble collagen with a higher content of beta-components of intramolecular origin.