BSA‐Polysaccharide Interactions at Negatively Charged Electrode Surface. Effects of Current Density.

Constant current chronopotentiometric stripping (CPS) peak H due to catalytic hydrogen evolution reaction on Hg‐containing electrodes appeared useful in the analysis of protein complexes with single‐stranded and double‐stranded DNA as well as with peptides. In dependence on stripping current (I_str), structural transition of the protein alone or in complexes can be followed as a result of the protein exposure to electric field effects. For the first time we show here that the CPS analysis can be used for the study of the interaction of BSA with a polysaccharide namely sodium alginate (SA). BSA‐SA complex formation was accompanied by the shift of the structural transition of BSA to lower ‐I_str intensities. Another polysaccharide dextran did not alter I_str‐dependent structural transition of BSA. BSA‐SA complex can be disturbed by an electric field effect or high ionic strength confirming the electrostatic nature of BSA‐SA interaction.     

Chronopotentiometric Analysis of Proteins at Charged Electrode Surfaces

Protein properties and functions are strongly dependent on the structure and amino acid content. In this work, catalytic hydrogen evolution reaction (CHER) of five proteins (human serum albumin, lysozyme, β‐synuclein, H2 A and H3 histones) were studied using constant current chronopotentiometric stripping (CPS) with the aim to find out the association between protein content and its electrochemical response. We have shown that the height and potential of CPS peak H in dependence on accumulation potential differed for the studied proteins, while the CPS peak area was almost the same for all of them. CV and CPS peaks H of Cys‐containing proteins appeared at less negative potentials in comparison to proteins without Cys, suggesting easier CHER. Acidic and basic proteins not containing Cys can be also recognized due to their different CPS response after their adsorption at the positive and negative charged interface.     

A Prym Construction for the Cohomology of a Cubic Hypersurface

Mumford defined a natural isomorphism between the intermediatejacobian of a conic-bundle over P² and the Prym variety of anaturally defined étale double cover of the discriminantcurve of the conic-bundle. Clemens and Griffiths used this isomorphismto give a proof of the irrationality of a smooth cubic threefold,and Beauville later generalized the isomorphism to intermediatejacobians of odd-dimensional quadric-bundles over P². We furthergeneralize the isomorphism to the primitive cohomology of asmooth cubic hypersurface in Pⁿ. We give two applications ofour construction: one is a special case of the generalized Hodgeconjectures and the other is an Abel-Jacobi isomorphism. 1991Mathematics Subject Classification: primary 14J70; secondary14J45.