Studies of Collagen Tissue Aging

Abstract

In a previous communication(1) it has been indicated that only those intermediary metabolites which are aldehydes are apparently able to act as tanning agents for hide powder collagen. Tanning in this context has been defined primarily by the relative repression at equivalent equilibrium pH's of the swelling phenomena of metabolite-treated as contrasted to untreated hide powders. As such, one, but only one of the several requisites for tannning ability have been fulfilled (2). In this report are recorded additional data indicating that improved stability of collagen preparations follows interaction with such metabolites.

Experimental. Glyceraldehyde - treated American Standard Hide Powder collagen (Frank F. Marshall, Ridgeway, Pa.) was prepared by reacting 15 g aliquots of isoelectric (pH 5.4) hide powder with 500 ml of 0.15M dl-glyceraldehyde in 0.15M phosphate buffers (pH 7.2) at 40°C for one week. (Less than 15% of the hide powder was solubilized by this treatment, whereas virtually all other metabolites resulted in drastic solubilization of the collagen preparation when similarly reacted.)

The neutral collagen was then washed with three 500-ml aliquots of distilled water at room temperature and dried to constant weight at 40°C. Two hundred milligram samples of this treated material were placed in graduated centrifuge tubes and overlaid with 10 ml of 0.5M aqueous solutions of NaCl, acetic acid, citric acid, 8M urea solutions and with a solution (1 mg/ml in PO₄ buffer) of purified bacterial collagenase (Worthington Biochemical Corp., Freehold, N. J.) at both room temperature and 40°C.

The apparent hydrated swelling volume of the solid (collagen) phase was recorded for each tube with respect to time of interaction, as indicated previously(3). The mean value of a minimum of 5 tubes was noted for each time interval.hyde. It is suggested accordingly that glyceraldehyde, the one major intermediary through which all known carbohydrate metabolic pathways must pass, can act as a potent tanning agent for collagen under conditions roughly approximating those of the extra-cellular body fluids.