Analytical use of a biochemical luminous membrane

Luminous membranes were prepared by immobilizing peroxidase (POD) to collagen matrix. The POD luminous membrane generated luninescence in the presence of luminol and H₂O₂, and the peroxide was determined in the concentration range 10-⁶-10-³ M by following luminescence emitted from the membrane. Glucose was determined using a luminous membrane in which POD and glucose oxidase (GOD) were coimmobilized. The luminous membranes appear to be feasible for the determination of enzyme substrates and enzyme activity.     

Stabilization and translation of immobilized mRNA on latex beads for cell-free protein synthesis system

The stability of immobilized mRNA against ribonucleases was investigated in a cell-free protein synthesis system. The plasmid-encoding protein A with the 20-mer poly(A) tail under the control of T7 promoter was constructed, and the corresponding mRNA was synthesized by T7 RNA polymerase reaction. The resulting mRNA was immobilized on oligo(dT)-immobilized latex beads by hybridization utilizing the poly(A) tail of mRNA at the 3'-terminus. The mRNA was stabilized against three types of nucleases (3'-OH exonuclease, 5'-OH exonuclease, and endonuclease) by immobilization. Translation of immobilized mRNA with a continuous-flow cell-free protein-synthesizing system from Saccharomyces cerevisiae was ascertained. Reusability of the immobilized mRNA as genetic information was also examined.     

Regioselective oxidative polymerization of 1,5-dihydroxynaphthalene catalyzed by bilirubin oxidase in a water–organic solvent mixed solution

Bilirubin oxidase (EC1.11.1.7) was used to catalyze the oxidative polymerization of 1,5-dihydroxynaphthalene to its polymer in a mixed solvent composed of dioxane, ethyl acetate, and acetate buffer. In an aqueous solution, the enzymatic oxidative polymerization hardly occurred and resulted in negligible yield mainly due to the poor solubility of 1,5-dihydroxynaphthalene. In the mixed solvent the conversion proceeded with a yield of ca. 70%. The polymer yield was studied with respect to reaction time and solvent components. Elemental analysis, UV-visible, fluorescent, and FT-IR spectroscopic analyses, proton NMR and electrochemical studies, and solubility in various organic solvents revealed that 1,5-dihydroxynaphthalene is polymerized by the C? C coupling. The molecular weight of the polymeric products solubilized with DMF varied from low molecular weight product to high molecular weight polymer. From the chromatographic studies, the organic solvent–insoluble residue was suggested to be highly polymerized material. Based on these findings a possible mechanism for enzymatic polymerization of 1,5-dihydroxynaphthalene is presented: less stable intermediates produced enzymatically from 1,5-dihydroxynaphthalene undergo coupling and polymerization to ortho-1,5-dihydroxynaphthalene polymer, thereby resulting in a regioselective polymerization of 1,5-dihydroxynaphthalene. © 1993 John Wiley & Sons, Inc.     

Silk protein production by the immobilized silk gland

The posterior silk glands of the silkworm, (itBombyx mori,) were immobilized in acrylamide gel. This immobilized organ produced silk protein in the presence of amino acids and energy sources. Amino acids began to be incorporated into the immobilized silk glands 2.5 h after incubation, and the incorporation continued for more than 20 h. The apparent lifetime of the posterior silk gland was remarkably elongated by the immobilization.     

Delayed luminescence of luminol initiated by a membrane-bound peroxidase

The luminescense of the luminol-H₂O₂ system was initiated by either free or membrane-bound horseradish peroxideae (HRP). The instantaneous luminescene decayed rapidly and was followed by the delayed luminescence in the presence of excess luminol. The delayed luminescence was characterized by a chain reaction, in which luminescence intensity increased exponentially. Membrane-bound HRP demonstrated that the delayed luminescence took place even in the absence of HRP if the instantaneous luminescence was initiated by HRP. A mechanism for the nonenzymatic luminescence is proposed and discussed.     

Nonenzymatic regeneration of NADPH from nadp in water-soluble polymer matrix-bound form

In order to inhibit the dimerization during the electrolytic reduction of nicotinamide adenine dinucleotide phosphate (NADP), NADP was covalently attached to a water-soluble polymer at proper intervals. Matrix-bound NADP was found to exhibit coenzymatic functions comparable to that of free NADP when it was coupled with glucose-6-phosphate dehydrogenase. According to the polarographic behaviors, matrix-bound NADP was electrolytically reduced at a controlled potential of -1.8 V vs. saturated calomel electrode (SCE). The electrolytically reduced product was identified as the enzymatically active NADPH by means of spectrophotometric and enzymatic assays. The dimerization of radical (NADP ) during the electrolytic reduction might be significantly retarded by immobilizing NADP to a water-soluble polymer matrix.     

Cell-free protein synthesis by posterior silk gland polyribosome

Polyribosome was prepared from the posterior gland of silkworms, where silkfibroin is specifically synthesized. Coupled with the corresponding enzymes, amino acids, ATP and GTP, silkfibroin was produced in a cell-free system. The production of silkfibroin was monitored by SDS polyacrylamide gel electrophoresis of the dansylated polypeptides. The polysome fraction was adsorbed on DEAE Sephadex. Using the immobilized polysomes, a genetic information-transducing bioreactor for producing a specified protein was assembled. The promising features of this bioreactor are discussed.     

Electrolytic process for regenerating nadp from nadph in a polymer matrix-bound form

Regeneration of nicotinamide adenine dinucleotide phosphate (NADP) from its reduced form (NADPH) was performed in a matrix-bound form by an electrolytic method. NADP was immobilized to alginic acid. No significant loss of coenzymic function was induced by the immobilization of NADP on the matrix. Bound NADP was soluble in water. Glucose-6-phosphate dehydrogenase (G-6-PDH) was taken as a model system of coenzyme requiring enzyme. G-6-PDH immobilized on alumina particles was coupled with the soluble form of bound NADP in a fluidized bed type of reactor. The enzymatically reduced coenzyme was electrolytically oxidized in the coenzyme regenerator of NADP from NADPH, which was found to cause no harmful loss of coenzymic function.     

Solid-phase luminescent catalyst immunoassay for human serum albumin with hemin as labeling catalyst

A solid-phase luminescent catalyst immunoassay is described for the determination of human serum albumin (HSA) in solution; hemin is used as a label which catalytically amplifies the sensitivity. The method is essentially a non-radioactive and non-enzymatic sandwich immunoassay. Anti-HSA antibody is covalently bound to a transparent plate, which then undergoes the immunochemical reaction with HSA in the test solution, and with the fixed amount of hemin-labeled anti-HSA antibody. After the two-step immunoreaction, the immunochemically-adsorbed hemin-antibody conjugate is quantified by means of the luminescence produced in a solution containing luminol and hydrogen peroxide. The luminescence intensity is correlated with the amount of HSA. The limit of detection for HSA is 1 ng ml^-1.