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Biomedical subjects

H Arwin

Publications and source records attributed to H Arwin.

8 recordsLinked to original sources
PubMed1987

Non-chromogenic peptide substrates for detection of enzymes by means of capacitance changes at metal electrodes.

A new type of substrate for enzyme detection has been developed. The substrate is non-chromogenic and is used in an assay method based on electrode adsorption. The rate of change in the electric capacitance of the electrode is monitored and taken as a measure of the substrate adsorption. Substrate adsorption is in turn proportional to substrate bulk concentration and thus subject to changes by enzymes. The new substrate introduces a new concept in enzyme detection: as it is non-chromogenic it may contain appropriate amino acids on both sides of the bond subject to enzymatic cleavage.

Electrochemistry↗
PubMed1985

A reflectance method for quantification of immunological reactions on surfaces.

A simple optical method for determination of thicknesses of organic layers on solid substrates is described. The method is based on the use of a substrate with a high refractive index, e.g., silicon, and reflection of light at an angle of incidence close to the pseudo-Brewster angle. Under these conditions, a reflectance minimum is obtained for light polarized in the plane of incidence. The presence of an organic layer on the surface will increase the reflectance, which is used to determine the thickness of the layer. The physical basis of the method is described briefly, and the application to immunology is demonstrated.

Antigen-Antibody Reactions↗
PubMed1979

The isoelectric point of thrombin and its behaviour compared to prothrombin at some solid surfaces.

We have shown that the isoelectric point of thrombin is high and that thrombin is a cation at the pH of blood. On the other hand, prothrombin has a low isoelectric point, being more anionic at the pH of blood. It was also found that thrombin adsorbs readily to surfaces, especially negatively charged surfaces, like behenic acid surfaces at pH 8.2. Furthermore, thrombin adsorbed onto behenic acid was active in the sense that it coagulated fibrinogen. The significance of the electric charge of the thrombin molecule in the mechanism of atherosclerosis is discussed.

Adsorption↗