The sephadex gel filtration characteristics of the neutral soluble proteins of embryonic bovine enamel

Abstract

1. 1.|The behaviour of the neutral soluble proteins of embryonic enamel when filtered through columns of Sephadex G-75 and G-100 resin was investigated. 2. 2.|The relative proportion of the protein which was retarded and which was excluded from the resin was dependent on the initial concentration of the protein solution. 3. 3.|Each of the peaks eluted from the Sephadex columns was studied by ultracentrifugation, amino acid analysis, and by its elution profile when rerun through the Sephadex column. All but one of the peaks were found to contain both high and low molecular weight material in a state of labile equilibrium. 4. 4.|The composition of the fractions which were retarded on the Sephadex columns was found to be dependent on both a concentration effect and the elution of distinctive chemical moieties at particular void-volume to elution-volume ratios. Each of the fractions which was retarded on the Sephadex columns formed high molecular weight aggregates of variable composition. 5. 5.|High molecular weight material which did not dissociate on dilution, and which was apparently unrelated to the interacting system, dissociated in 6 M urea, and was therefore also composed of non-covalently bonded aggregates. The average molecular weight of the aggregates was found to be 2.9·10 6, and the estimated molecular weight of the smallest aggregate, 1.86·10 6. 6. 6.|The results of these experiments characterize the enamel proteins as a multicomponent system involving different aggregate complexes of approximately the same size.