Isolation and Partial Characterization of a Human Vitamin D-binding Plasma Protein

摘要: Abstract Vitamin D circulates in human plasma bound to a specific transport protein. This protein differs from the lipoproteins and has hydrated density greater than 1.21. The purification of vitamin D-binding was accomplished by use ammonium sulfate fractionation, DEAE-Sephadex chromatography, sulfoethyl-Sephadex gel chromatography. These procedures resulted highly purified preparation which had been approximately 15,000-fold. appeared homogeneous Ouchterlony immunodiffusion analyses, immunoelectrophoresis, analytical ultracentrifugation. separated into two components on electrophoresis, both with α1 mobility. most anodal component carried D3, whereas cathodal form devoid this vitamin. molecular weight determined equilibrium ultracentrifugation estimated sedimentation coefficient chromatography 53,000. Determinations reduced alkylated 6 m guanidine hydrochloride gave same value as found under physiological conditions, suggesting that is not composed subunits. frictional ratio (f/f0) low for protein, indicating close spherical appearance occurrence normal serum, urine, cerebrospinal fluid established analyses antiserum against Indirect estimates indicated concentration serum 5 µg per ml.