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°C. as compared with that removed at 3°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.

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