PubMed · 5637735
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Y Z Frohwein. 1968-02-17. De-esterification using ion exchangers.. https://doi.org/10.1038/217642a0
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To investigate the effect of automated isoelectric focusing conditions in the PhastSystem, e.g., the point of sample application, prerun and separation times, and minimized gels on isotransferrin band pattern, human sera were analyzed with native transferrin iron load, after iron saturation or iron depletion in vitro. Varying the focusing conditions we found (i) Point of sample application (anode, middle of the gel, cathode) strongly affected transferrin iron loss. It was greatest at the anode and least at the cathode. (ii) Without prerun, distinct transferrin iron loss also occurred. A short prerun time prevented iron loss, but increasing it did not improve transferrin iron load stability as stated by others. (iii) An inappropriately long separation time inevitably yielded iron loss. In conclusion, inappropriate isoelectric focusing conditions strongly affect iron load stability of isotransferrins (obviously via low pH within the gel), resulting in transferrin iron release and cofocusing of isotransferrins with different sialic acid or iron contents. For determination of carbohydrate-deficient transferrin, such conditions resulted in overestimation of the marker of chronic alcohol abuse. Our findings may be of guiding importance for isoelectric focusing of protein-ligand complexes. We recommend the procedure described for development of isoelectric focusing of protein-ligand complexes.
The molecular architecture of lipopolysaccharide (LPS) isolated from all O serotypes of Vibrio parahaemolyticus was investigated. In gel chromatography on a Sephadex G-50 column, the degraded polysaccharide fraction prepared from each serotype LPS by mild acid hydrolysis yielded only core oligosaccharide (Frc II) and monosaccharide (Frc III) fractions, but no fraction (Frc I) corresponding to O polysaccharide chain consisting of polymeric repeating oligosaccharide units. Compositional sugar analysis of Frc II and III suggested that the sugar chain of LPS of all the serotypes of V. parahaemolyticus consisted of at most ten monosaccharides. Sodium dodecylsulfate-polyacrylamide gel electrophoresis of the LPS resulted in no doublet ladder band similar to that observed for S-type enterobacterial LPS. These results are compatible with the interpretation that V. parahaemolyticus O serotypes from O1 to O13 all produce R-type LPS, despite the morphologically smooth appearance, demonstrated virulence and serological O-specificity.