Isoelectric focusing of alkaline phosphatases. A focusing-disc electrophoresis transfer technique

Isoelectric focusing on cellulose acetate membrane: a separation procedure for alkaline phosphatase isoenzymes

An isoelectric focusing technique for the separation of alkaline phosphatase isoenzymes on cellulose acetate membrane is described. Optimal conditions for isoelectric focusing were established by changing ampholine concentration and focusing conditions. Bone, liver, intestinal, and placental isoenzymes can be resolved into various sub-bands in a pH range of 4.1 to 5.2. These sub-bands were correlated with the findings of electrophoretic isoenzyme separation. The whole procedure proves very simple to perform and comparatively time saving (4 h). This procedure may help clarify the problems of ALP isoenzyme differentiation when electrophoretic patterns are unresolved.

Isoelectric focusing of human tissue alkaline phosphatase isoenzymes in agarose gel

Human tissue alkaline phosphatases obtained by butanol treatment of tissue homogenates were subjected to isoelectric focusing in agarose gel. Inactivation of alkaline phosphatases by ampholytes was prevented by incorporating zinc into the gel prior to electrofocusing and to the authors' knowledge this has not been reported before. The addition of zinc did not alter the pH gradient and the method was reproducible. Ampholytes from two different manufacturers differed in their requirements for zinc in preventing inhibition of alkaline phosphatase. The method is more rapid than previously described methods and is very sensitive.

Biochemistry of alkaline phosphatase isoenzymes

The review discusses the similarities and differences between the common isoenzymatic forms of ALP. Methods for separating, measuring, and purifying the isoenzymes on the basis of these differing properties are described. The evidence is reviewed for the existence of different genes coding for different isoenzymes, and the current state of knowledge is surveyed concerning the location, development, function, and regulation of the isoenzymes. Finally, some unusual forms of ALP which may appear in the circulation are described.

Analysis of Staphylococcus aureus cytoplasmic membrane proteins by isoelectric focusing

Cytoplasmic membranes were isolated from late-exponential phase Staphylococcus aureus 6539 P and the membrane proteins examined under non-denaturing conditions by thin-layer isoelectric focusing (TLIEF) in a pH 3.5-9.5 gradient. Isolated membrane preparations retained protein integrity as judged by the demonstration of membrane bound adenosine triphosphatase (ATPase) activity in addition to four other solubilized membrane enzyme markers. Membranes were effectively solubilized with 2.5% Triton X-100 (final concentration). Examination of Triton X-100 solubilized membrane preparations established the presence of 22 membrane proteins with isoelectric points between 3.7 and 6.0. The focused proteins displayed the following enzymatic activities and isoelectric points by zymogram methods: ATPase (EC 3.6.1.3), 4.20; malate dehydrogenase (EC 1.1.1.37), 3.90; lactate dehydrogenase (EC 1.1.1.27), 3.85; two membrane proteins exhibited multiple bands upon enzymatic staining NADH dehydrogenase (EC 1.6.99.3), 4.25, 4.35; succinate dehydrogenase (EC 1.3.99.1), 4.85, 5.10, 5.35.

Affinity elution from a phosphonic acid-Sepharose derivative in the purification of human liver alkaline phosphatase

The compound p-aminobenzylphosphonic acid has been coupled via an azo linkage to tyraminyl-Sepharose 4B. This derivative at pH 6.0 bound most of the protein and all of the alkaline phosphatase in a crude preparation from human liver. The phosphatase was selectively eluted with the substrate 2-naphthylphosphate and a purification of 400-fold obtained. This step, when incorporated into a procedure for the purification of human liver alkaline phosphatase, yielded essentially pure enzyme.

Affinity purification and some molecular properties of human liver alkaline phosphatase

Alkaline phosphatase from human liver was purified to homogeneity. The purification procedure included solubilization with butanol, fractionation with acetone, and chromatography on concanavalin A-Sepharose, DEAE-cellulose, Sephadex G-200 and DEAE-Sephadex. Purity was established by standard and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. The isoelectric point of the protein was determined to be 4.0. Sephadex-gel filtration gave a mol.wt. of 146000, although a higher value was obtained in the presence of 100mM-NaC1. The subunit mol.wt. 76700, was determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Neuraminidase treatment resulted in two enzyme-activity bands on isoelectric-focused gels with isoelectric points of 6.6 and 6.8. The desialylated enzyme gave only one protein band on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis with a subunit molecular weight indistinguishable from that of the non-neuraminidase-treated protein. The desialylated enzyme was more readily denatured by sodium dodecyl sulphate in the presence of mercaptoethanol than was the native enzyme.

Alkaline phosphatase isoenzymes of human kidney and urine

Kidney and urinary alkaline phosphatases have been studied by starch gel electrophoresis. Kidney extracts have shown individual variations and the patterns obtained with cortex and medulla have been clearly different. There are in urine and kidney extracts, phosphatases which share similar properties with regard to electrophoretic mobility, non-susceptibility to treatment with neuraminidase and inhibition by L-phenylalanine.