Isolation and physical characterization of hyaluronic acid prepared from bovine nasal septum by cetylpyridinium chloride precipitation.

Raw extract in 2 m CaCl2 of bovine nasal septum cartilage was eluted from 4 per cent agarose gel to give a "void volume" Fraction v-4, which was indistinguishable in composition and behavior on viscometric and sedimentation analysis from the densest fraction obtained by associative centrifugation in a cesium chloride density gradient. The sulfated proteoglycan was precipitated (Fraction A) by cetylpyridinium chloride from acidic solutions of Fraction v-4 or of dialyzed raw ectract. Neutralization under conditions of low ionic strength precipitated a further small fraction (B), which contained from 0.5 to 1 per cent of the uronic acid in the original extract. Analysis by associative and dissociative density gradient centrifugation demonstrated that Fraction B resembled in effective density known samples of hyaluronic acid from other sources. Gel chromatography of proteolytic digests of Fractions A and B on 6 per cent agarose indicated that cetylpyridinium chloride precipitation essentially separated sulfated proteoglycan (A) from hyaluronic acid (B). A viscosity-average molecular weight of about 5 x 10(5) was estimated for a sample of Fraction B purified in a dissociative (4 M guanidine hydrochloride + CsCl) density gradient. Sedimentation velocity data were consistent with this result. Analysis of hexosamines showed that the sample contained 96 per cent glucosamine, confirming the identification of hyaluronic acid. The proteoglycan fraction (A) resembled "subunits" in its sedimentation behavior.