Most cellular interactions essential for the development of an immune response involve the membrane glycoproteins encoded in the major histocompatibility gene complex. The products of the I region, the class II histocompatibility molecules (Ia molecules), are essential for accessory cells such as macrophages to present polypeptide antigens to helper T cells. This interaction, antigen presentation, is needed for T-cell recognition of the antigen and its consequent activation. How the Ia molecules regulate the immune response during antigen presentation is not known, although it is commonly thought to result from their association with the presented antigen. Recent studies, including the elucidation of the structure of the T-cell receptor, favour recognition of a single structure, an antigen-Ia complex. Here we report attempts to determine whether purified Ia glycoproteins have an affinity for polypeptide antigens presented by intact cells in an Ia-restricted manner. We first identified the epitope of a peptide antigen involved in presentation. Several laboratories have shown that globular proteins are altered (processed) in intracellular vesicles of the antigen-presenting cell before antigen presentation. A major component of the T-cell response is directed toward determinants found in the unfolded or denatured molecule, and our laboratory has shown that the determinant of the hen-egg lysozyme protein (HEL), presented in H-2k mice to T cells, is a sequence of only 10 amino acids. This portion resides in an area of the native molecule partially buried inside the molecule, in a beta-sheet conformation. To be presented, intact or native HEL must first be processed in acidic intracellular vesicles. Having isolated the peptide responsible for T-cell recognition of HEL, we sought a physical association of this peptide with purified, detergent-solubilized I-Ak molecules from B-hybridoma cells. We have found such an association, which may explain the role of the Ia glycoproteins in cellular interactions.

Binding of immunogenic peptides to Ia histocompatibility molecules

Determination of free and total homocysteine in human plasma by high-performance liquid chromatography with fluorescence detection.

Analysis of glutathione: implication in redox and detoxification.

Most synthetic polymers are made from petroleum feedstocks. Given the non-renewable nature of these materials, there is increasing interest in developing routes to polymeric materials from renewable resources. In addition, there is a growing demand for biodegradable polymeric materials. Polycarbonates made from CO(2) and epoxides have the potential to meet these goals. Since the discovery of catalysts for the copolymerization of CO(2) and epoxides in the late 1960's by Inoue, a significant amount of research has been directed toward the development of catalysts of improved activity and selectivity. Reviewed here are well-defined catalysts for epoxide-CO(2) copolymerization and related reactions.

Discrete Metal-Based Catalysts for the Copolymerization of CO2 and Epoxides: Discovery, Reactivity, Optimization, and Mechanism

Rapid high-performance liquid chromatographic assay for total homocysteine levels in human serum.

Fluorimetric determination of secondary amino acids by 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole

A novel fluorogenic reagent for thiols : ammonium 7-fluorobenzo-2-oxa-1, 3-diazole-4-sulfonate

High-performance liquid chromatography and sensitive detection of amino acids derivatized with 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole.

Pre-column labelling for high-performance liquid chromatography of amino acids with 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole and its application to protein hydrolysates☆

Apres separation par chromatographie d'echange d'ion, reaction avec le reactif du titre, les amino et iminoacides et les thiols sont doses par spectrometrie de fluorescence. La methode est appliquee a l'analyse d'echantillons de sang depose sur disques de papier afin de determiner les erreurs de metabolisme a la naissance

Yoshihiko Watanabe

Papers

Fluorimetric determination of secondary amino acids by 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole

A novel fluorogenic reagent for thiols : ammonium 7-fluorobenzo-2-oxa-1, 3-diazole-4-sulfonate

High-performance liquid chromatography and sensitive detection of amino acids derivatized with 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole.

Pre-column labelling for high-performance liquid chromatography of amino acids with 7-fluoro-4-nitrobenzo-2-oxa-1,3-diazole and its application to protein hydrolysates☆

Liquid chromatographic determination of amino and imino acids and thiols by postcolumn derivatization with 4-fluoro-7-nitrobenzo-2,1,3-oxadiazole.