Human lysosomal beta-galactosidase catalyzes the hydrolysis of beta-galactosides via a double displacement mechanism involving a covalent glycosyl enzyme intermediate. By use of the slow substrate 2,4-dinitrophenyl-2-deoxy-2-fluoro-beta-D-galactopyranoside, a glycosyl enzyme intermediate has been trapped on the enzyme. This has allowed the catalytic nucleophile to be identified as Glu-268 by pe...

Displacement of spin-labeled drugs from drug-specific antibodies in human serum can be measured by use of electron spin resonance. This "spin immunoassay" has advantages of speed, simplicity, and small volume requirements over other standard techniques such as gas-liquid, liquid-liquid, or thin-layer chromatography. Unlike radioimmunoassay, there is no need to separate free and bound label and ...

Tethering is a screening technique for discovering small-molecule fragments that bind to pre-determined sites via formation of a disulphide bond. Tethering screens traditionally rely upon mass spectrometry to detect disulphide bind formation, which requires a time-consuming liquid chromatography step. Here we show that Tethering can be performed rapidly and inexpensively using a homogenous fluo...

The determination of creatinine by HPLC was performed by direct injection of serum onto the column, and after ultrafiltration of the sample, and the results were compared. A modified weak cation exchange column was used for HPLC. This eliminates the protein displacement effect and the Gibbs-Donnan effect, thus permitting a rapid direct analysis. Three of the four ultrafiltration methods gave al...

In the present paper the separation of three amino acids applying ligand exchange chromatography in single and dual chiral systems was modeled using the dispersive equilibrium model. The investigated systems consist of a commercially available non chiral column and a commercially available chiral column using a chiral mobile phase. With the experimentally determined model parameters and the mul...

In the present article we describe the design and evaluation of a synthetic receptor that binds to the exterior surface of chymotrypsin and disrupts its interaction with proteinaceous inhibitors, such as soybean trypsin inhibitor, basic pancreatic trypsin inhibitor, ovomucoid turkey inhibitor, and Bowman-Birk inhibitor. Using enzyme kinetics, nondenaturing gel electrophoresis, and gel filtratio...

Zinc isotope separations were studied by displacement chromatography using the chelating properties of malate, citrate and lactate exchange resin and EDTA as ligands. After each chromatographic operation, the heavier zinc isotopes were found to preferentially fractionated into the carboxylate complex solution phase. The separation coefficients (epsilon) for zinc isotope separation had the large...