ABSTRACT
The manufacture of human serum albumin by chromatographic procedures involves gel filtration chromatography as a final polishing step. Despite this step being essential to remove high molecular weight impurity proteins and thus ensure a stable and safe final product, it is relatively inefficient. This paper explores the use of hydrophobic charge induction chromatographic media, MEP HyperCel as an alternative to Sephacryl S200HR gel filtration for the polishing of human serum albumin derived by ion exchange chromatographic purification of Cohn Supernatant I. The use of MEP HyperCel results in a product with a higher purity than achieved with gel filtration and in a less time consuming manner and with potential resource savings. MEP HyperCel appears to have great potential for incorporation into downstream processes in the plasma fractionation industry as an efficient means of achieving polishing of intermediates or capture of proteins of interest.
Subject(s)
Chromatography, Ion Exchange/methods , Serum Albumin/isolation & purification , Chromatography, Ion Exchange/instrumentation , Drug Contamination , Humans , Hydrophobic and Hydrophilic Interactions , Serum Albumin/analysis , Serum Albumin/chemistry , Serum Albumin/standardsABSTRACT
Sensory functions of primary cilia rely on ciliary-localized membrane proteins, but little is known about how these receptors are targeted to the cilium. To further our understanding of this process, we dissected the ciliary targeting sequence (CTS) of fibrocystin, the human autosomal recessive polycystic kidney disease gene product. We show that the fibrocystin CTS is an 18-residue motif localized in the cytoplasmic tail. This motif is sufficient to target green fluorescent protein (GFP) to cilia of ciliated cells and targets GFP to lipid rafts if the cells are not ciliated. Rab8, but not several other Rabs implicated in ciliary assembly, binds to the CTS in a coimmunoprecipitation assay. Dominant-negative Rab8 interacts more strongly than wild-type or constitutively active Rab8, and coexpression of this dominant-negative mutant Rab8 blocks trafficking to the cilium. This suggests that the CTS functions by binding regulatory proteins like Rab8 to control trafficking through the endomembrane system and on to the cilium.
Subject(s)
Cytoplasm/chemistry , Cytoplasm/metabolism , Receptors, Cell Surface/chemistry , Receptors, Cell Surface/metabolism , Amino Acid Sequence , Animals , Cell Line , Cilia/chemistry , Cilia/metabolism , Humans , Mice , Molecular Sequence Data , Protein Transport , Receptors, Cell Surface/genetics , rab GTP-Binding Proteins/genetics , rab GTP-Binding Proteins/metabolismABSTRACT
Human serum albumin is a well tolerated therapeutic for the treatment of hypovolemia. Despite all commercial human albumin preparations being derived from plasma, these products can have a highly variable colour. Albumin samples derived from ethanol precipitation and chromatographic fractionation procedures were evaluated for bilirubin and biliverdin levels and by spectrophotometry. It was shown that albumin derived from a chromatographic process, which had a bilirubin:albumin ratio similar to that observed in plasma, had a vibrant yellow appearance. The albumin derived from ethanol precipitation had undetectable levels of bilirubin, and the amber colour of this product was attributed mainly to residual haem. The presence of bilirubin during pasteurisation led to oxidation to biliverdin, with a resultant colour change from yellow to yellow/green. Given that the antioxidant properties of bilirubin are well established, it is possible that bilirubin helps protect albumin from oxidation during the pasteurisation step.
