Isolation of copper biochelates from Methylosinus trichosporium OB3b and soluble methane monooxygenase mutants.

Methylosinus trichosporium OB3b produces an extracellular copper-binding ligand (CBL) with high affinity for copper. Wild-type cells and mutants that express soluble methane monooxygenase (sMMO) in the presence and absence of copper (sMMOc) were used to obtain cell exudates that were separated and analyzed by size exclusion high-performance liquid chromatography. A single chromatographic peak, when present, contained most of the aqueous-phase Cu(II) present in the culture medium.

Evaluation of Surface Plasmon Resonance (SPR) for Heparin Assay.

Heparin adsorption onto polyethylene imine (PEI) films was investigated. The adsorption was followed with time-dependent surface plasmon resonance (SPR) for PEI cast on gold films, and the thickness of the adsorbed heparin was determined by fitting the angular reflection curves to Fresnel's equations. The average thickness of the PEI determined the heparin adsorption range and it was found that both heparin binding capacity and sensitivity increased with PEI thickness.

Evaluation of Surface Plasmon Resonance (SPR) for Heparin Assay.

The concentration of heparin, an anticoagulant in blood, is usually inferred from clotting type assay, which determines a parameter related to the heparin activity. Because of the heterogeneity of heparin, however, it is desirable to monitor the absolute concentration of heparin directly in the clinical range of 0-2 U/ml. Surface plasmon resonance (SPR) provides a optical direct method of monitoring binding events.