Some properties of cold neutral salt extracts of fresh guinea pig dermis have been described in terms of viscosity, electrophoresis and sedimentation patterns, partial composition, the collagen content, conditions for extraction of collagen, and the effect of certain enzymes. Viscosity of the extracts depended on the collagen in solution as demonstrated by removal of this protein by precipitation or enzymatic degradation. The intrinsic viscosity of the crude 0.45 M extract, as well as that of the isolated collagen was 14.5, identical with that for collagen dissolved by dilute acid, indicating the same high asymmetry ratio for both. Electrophoresis of the skin extracts revealed a slow moving, high, sharp, poorly diffusing boundary in addition to a pattern superficially resembling that of serum. The ultracentrifuge pattern revealed a slowly sedimenting, hypersharp boundary following a large rapidly diffusing peak. The slow moving boundaries in both patterns were abolished by collagenase or heat precipitation of the collagen fraction. Hyaluronidase had no effect on either pattern. Neutral sulfate, chloride, and phosphate extracted more collagen than did thiocyanate. Very little collagen was extracted at 37 degrees C. as compared with that removed at 3 degrees C. A two stage fractionation procedure employing dilute trichloroacetic acid and ethanol is described for the isolation and purification of soluble collagen from crude extracts.

Collagen↗

PubMed1958

Studies on the formation of collagen. II. The influence of growth rate on neutral salt extracts of guinea pig dermis.

The total amount of neutral salt-extractible collagen in the skin of growing, suckling guinea pigs amounted to about 10 per cent of the total collagen of the dennis. This is roughly equivalent to a 1 to 2 day increment in dermal collagen incident to growth. Fourteen days of static weight maintained by limited caloric intake reduced the neutral salt-extractible collagen to very low levels. Following this period, 5 to 7 days of steady weight gain induced by ad lib. feeding was required to produce significant increases in this collagen fraction. Return to control levels occurred within 12 days of continuous growth. The amount of collagen extracted from the dermis of young guinea pigs with cold neutral salt solutions varied directly with growth rate (weight gain) and was greatly diminished after short periods of restricted caloric intake. Two days of fasting diminished the total extracted collagen by one-half. Three consecutive extractions with citrate buffer pH, 3.5, of the residues remaining after exhaustive saline extraction removed 40 per cent more collagen from the skins of actively growing animals than from those of animals fasted for 2 days. However, subsequent extraction of residues with dilute acetic acid equalized the total amount of collagen extracted at acid pH from the two groups. The viscosity of cold neutral extracts was unrelated to the concentrations of non-collagenous proteins and carbohydrates but varied directly with the collagen content.

Animals↗

PubMed1958