The effect of different isolation procedures on the yields of insulin-like growth factors from XXXX plasma.

@entity1 @entity12067 @entity442 @entity5100 @entity3459 @entity1068
Various procedures for the isolation of insulin-like growth factors (IGF's) from @entity1 plasma were evaluated with emphasis upon the yields of each species obtained. The procedures which were evaluated as first steps from plasma and mixed Cohn fractions included acid- @entity1068 extraction, @entity3459 , ion-exchange chromatography and gel filtration. Certain two-step combinations of these techniques were also evaluated in order to obtain higher fold-purification. Fractions obtained were tested initially using a competitive binding protein assay and then by radioimmunoassay (RIA) for @entity12067 . The results indicated that acceptable yields of @entity12067 were obtained by initial gel filtration of acidified plasma on Sephadex G-75 at pH 2.5 followed by chromatography on S.P. Sephadex C-25. Isoelectric focusing of the active fraction thereby obtained under these conditions and subsequent R.I.A. indicated total recoveries of @entity12067 of about 23 and 96 mU/litre respectively. Peak recoveries of @entity442 were obtained in a fraction of pI 7.6-8.2 and @entity5100 between pI 5.9 and 6.9. The order in which the two steps of gel filtration and ion exchange chromatography were carried out appeared to alter the distribution of IGF's obtained. When ion exchange chromatography was used as the first step, most of the activity was obtained in fractions of pI 4.4-5.9 and was not immunoreactive @entity442 or II.
