Purification of proteins from polyacrylamide gels, free of detergent or dye

The effect of monostearoylglycerol on the metabolism of chylomicron-like lipid emulsions injected intravenously in rats

In rats, remnant particles derived from chylomicron-like emulsions containing 1,3-dioleoyl-2-stearoylglycerol (OSO) are removed from plasma more slowly than remnants derived from triolein emulsions. The effect associated with a saturated acyl chain at the glycerol 2-position could be reproduced by incorporating 2-stearoylglycerol (MS) in a triolein emulsion. When MS solubilized with rat albumin or in plasma was injected before the injection of a triolein emulsion, clearance of the triolein emulsion was unchanged. The metabolic fate of MS, monitored with 14C-labelled MS, was similar whether incorporated in triacylglycerol emulsion or injected independently. More than 95% of MS had disappeared from the circulation by 5 min after the injection and the radioactivity was found in liver, spleen, muscle and adipose tissue. Some MS label appeared in plasma triacylglycerol. Remnants made in vitro by incubating triolein or OSO emulsions with post-heparin plasma showed no differences in their disappearance from plasma. With OSO emulsion, the in vitro remnants were found to contain more MS than remnants made in vivo in hepatectomized rats. Simultaneous injections of mixtures containing OSO and triolein emulsions, or triolein emulsions with and without MS, each labelled with either [3H]cholesteryl oleate or [14C]cholesteryl oleate showed consistently slower remnant removal and decreased liver uptake of the emulsions containing OSO or MS. Affinity columns and immunodiffusion all indicated that there was no difference in the amounts of apolipoprotein E associated with OSO or triolein particles. The protein spectra of in vivo remnants derived from OSO and triolein emulsion were also similar when examined by SDS-PAGE and isoelectric focusing gels. Our results show that the effects due to OSO or MS are mediated by the presence of MS in the emulsion particle surface, while indirect effects expressed in plasma or liver are excluded. The precise mechanism of the effect remains to be established, but it does not correlate with measurable changes in the spectra of apolipoproteins associated with the emulsion remnants.

Isolation of aldehyde oxidase (EC 1.2.3.1) from potato extracts by preparative page

A method is proposed for the isolation (and purification) of enzymes, with retention of their activity, from solutions or gels of preparative PAGE runs. It is based on the inclusion of Sephadex G-25 as a supporting medium for a collector buffer in otherwise normal disc-PAGE gels. The collector buffer has a lower pH and higher concentration than the stacking gel buffer. This makes the proteins concentrate in a very narrow, slowly moving band in the Sephadex on electrophoresis, and makes their recovery easy. The method is illustrated by the isolation of aldehyde oxidase from potato extracts (which was unsuccessful by classical methods), and of one isoenzyme from commercial lipoxygenase after preparative PAGE. Recovery of chicken egg albumin after PAGE was over 90%.