Important discrepancies in isoelectric points (pI) of beta-lactamases were observed depending on the experimental procedure used for their determination: isoelectric focusing (IEF) in sucrose density gradients or analytical IEF in thin-layer polyacrylamide gels (PA). The variations, negligable in the case of TEM-like beta-lactamases, appeared to be important in the case of cephalosporinases and...

Isoelectric focusing of proteins in a silica nanofluidic channel filled with citric acid and disodium phosphate buffers is investigated via numerical simulation. Ions in the channel migrate in response to (i) the electric field acting on their charge and (ii) the bulk electroosmotic flow (which is directed toward the cathode). Proteins are focused near the low pH (anode) end when the electromig...

Analytical isoelectric focusing (IEF) has been applied to the study of the apolipoprotein components of rat serum high density and very low density lipoproteins. The apolipoproteins were separated on 7.5% polyacrylamide gels containing 6.8% urea, with a pH gradient of 4-6. The middle molecular weight range apolipoproteins were identified on IEF gels by the use of apolipoproteins purified by ele...

Factitious proteinuria is an unusual finding. We present a case in which clinical suspicion was aroused by the disparity between the clinical history and findings and the 24-h excretion of protein in urine. Electrophoresis of the patient's serum and urine confirmed the presence of an unusual protein. By isoelectric focusing we identified it as egg-white, a finding confirmed by immunofixation wi...

A comparative chromatography of polyphenoloxidase isolated from barley, steeped barley, and green malt was made. It consisted ofextraction, precipitation, ion-exchange chromatography, gel filtration, and electrofocusing. Polyphenoloxidase was resolved into a high-molecularweight enzyme and a low-molecular-weight one. The proportion of the two enzymes underwent variations during malting. An incr...

Fast and slow rat transferrins were isolated by isoelectric focusing and prepared in their di- and monoferric forms. A comparison of the rates of iron release between fast and slow monoferric transferrins when incubated with reticulocytes or injected in vivo showed no significant difference in the behavior of the two isotransferrin species. Reticulocyte uptake of diferric transferrin resulted i...

We report a microchip-based method for separating charged molecules according to electrophoretic mobility. The method is based on opposed electroosmotic, electrophoretic and convective forces. Similar to isoelectric focusing, solute can be accumulated into stationary zones, but without use of ampholytes. The method of "microchip countercurrent electroseparation" described here has potential app...

Isoelectric focusing of proteins is now well established as a powerful tool in protein chemistry following its introduction a few years ago (1, 2). Unfortunately, this new technique has not yet found practical day to day use in the·, clinical laboratory. This communication describes a reproducible and easy method for gel isoelectric focusing (3, 4, 5)! It also contains the preliminary' results ...

Three and four N-acetylhexosaminidase components, from ram testis and epididymis respectively, have been separated by ion-exchange chromatography on DEAE-cellulose. Although they all have the same molecular weight (approx. 140000) and very similar catalytic properties towards the synthetic substrates, 4-methylumbelliferyl N-acetyl-beta-glucosaminide and N-acetyl-beta-galactosaminide, isoelectri...