Glucose, fructose, mannose and/or glucose-1-phosphate-releasing activity stains for glycosidases and glycosyltransferases in gels after isoelectric focusing

beta-Fructofuranosidase, alpha-glucosidase, beta-glucosidase, alpha-mannosidase, beta-mannosidase, sucrose phosphorylase, glucosyltransferase and fructosyltransferase were separated by isoelectric focusing and sensitively detected to be slightly diffuse and insoluble spots in thin-layer gels, supported by a glass plate, by release of monosugars or a sugar phosphate, followed by conversion to glucose-6-phosphate (G6P) and then by reduction of NADP+ to NADPH, terminated by the formation of reduced Nitroblue Tetrazolium (NBT). Approximately 1-10 mU of enzyme was focused and the gel, after washing with a buffer, was partially dried and directly stained by uniformly spreading on the gel surface a staining medium containing sucrose or nitrophenyl glycosides as substrates, intermediary enzymes such as hexokinase, mutase and/or isomerase, NADP+, ATP, Mg+, phenazine methosulfate (PMS) and NBT. Specific staining procedures for each of these activities, on sucrose or on the glycosides as substrates, and staining procedures for multiple activities are described, with the conditions necessary for optimal development.

Isoelectric focusing in immobilized pH gradients: applications in clinical chemistry and forensic analysis

The applications of isoelectric focusing in immobilized pH gradients in clinical chemistry and forensic analysis are reviewed. Strong emphasis is given to the separation of serum proteins, in particular alpha 1-acidic glycoprotein, acid phosphatase, alkaline phosphatase, alpha 1-antitrypsin, apolipoproteins, complement component, factor B, factor XIIIB, group-specific component, lecithin:cholesterol acyltransferase, phosphoglucomutase, prealbumin, protein C and transferrin. The analysis of human parotid salivary proteins is discussed and an assessment is given of the state of the art in thalassaemia screening.

Use of physiological substrates for zymograms of disaccharidases after separation in immobilized pH gradients

A new technique is described for in situ visualization of the activity of intestinal disaccharidases after isoelectric focusing in immobilized pH gradients using their physiological substrates. The reaction principle is based on the oxidation of D-glucose, liberated by the disaccharidases, into D-gluconolactone and the production of NADH by glucose dehydrogenase. At the sites of enzymatic activity, tetrazolium salts present in the reaction mixture are reduced to relatively water-insoluble formazans by NADH. The rate of formazan production is increased by the presence of phenazine methosulfate. An additional modification of the technique involves the use of polyvinyl alcohol in the substrate solution. Due to the increase in the viscosity of the substrate solution, leakage of the enzyme from the IPG gels is minimized. Incubation times can thus be prolonged without loss of resolution and band-blurring.

Isoelectric focusing of basic proteases in immobilized pH gradients

By exploiting a new, alkaline immobilized pH gradient spanning the pH 10-11 interval, it has been possible to focus and to detect, by in situ zymogramming with cellulose acetate foils impregnated with fluorogenic substrates, 2 alkaline proteases, namely elastase and trypsin. Elastase gave a sharp array of 3 bands, with the following pIs (at 10 degrees C): 10.60 (major component), 10.53 (intermediate species) and 10.45 (minor isoform). Trypsin was resolved into 2, about equally abundant, species having pIs of 10.70 and 10.53. However, the latter enzyme gave smears in between these 2 forms and also anodic to the lower pI species. As hydrophobic interaction with the Immobiline matrix was excluded, it is suggested that these smears represent product of auto-digestion due to the very alkaline pH during the focusing process.