Determination of hydrogen peroxide by iron(III) complex of thiacalix[4]arenetetrasulfonate on a modified ion-exchanger with peroxidase-like catalytic activity.

An iron(III) complex of thiacalix[4]arenetetrasulfonate on a modified anion-exchanger (Fe3+-TCAS(A-500)) has shown high peroxidase-like activity at pH 5 - 6 for the reaction of quinoid-dye formation between 3-methyl-2-benzothiazolinone hydrazone and N-(3-sulfopropyl)aniline in the presence of hydrogen peroxide. Utilizing the peroxidase-like activity of Fe3+-TCAS(A-500) for this reaction, a method using Fe3+-TCAS(A-500) was applied for the spectrophotometric determination of hydrogen peroxide. The calibration curve by the method using Fe3+-TCAS(A-500) was linear over the range from 1 to 10 microg of hydrogen peroxide in a 1 ml sample solution. The apparent molar absorptivity for hydrogen peroxide was 2.4 x 10(4) l mol(-1) cm(-1). which was about 80% of that by peroxidase under the same conditions. This determination method of hydrogen peroxide using Fe3+-TCAS(A-500) was applied for the determination of glucose in diluted normal and abnormal control serum I and II.

Adsorption of mutagens to chlorophyllin-chitosan, an insoluble form of chlorophyllin.

Chlorophyllin, a water soluble derivative of chlorophyll is known to suppress the mutagenic and carcinogenic actions of compounds having polycyclic structures, e.g. heterocyclic amines and aflatoxin B1. There is evidence that this suppressing effect arises, at least in part, by a complex formation between the porphyrin-like structure of chlorophyllin and the planar molecular surfaces of these compounds. We report here that chlorophyllin can form an insoluble salt-like material when mixed with chitosan, a polyglucosamine, and that the solid chlorophyllin-chitosan thus prepared can efficiently trap polycyclic mutagenic compounds. The adsorbed polycyclic mutagens were elutable with buffers of acidic pH, but only to small extents. Chlorophyllin-chitosan may be expected to be useful as an intercepting agent against polycyclic mutagens and carcinogens.

Uricase-like catalytic activity of ion-exchange resins modified with metalloporphyrins.

The uricase-like catalytic activity of the ion-exchange resins modified with metalloporphyrins has been investigated through the oxidation of uric acid. The anion-exchange resins modified with Mn(3+)-tetrakis(sulfophenyl)porphine and the cation-exchange resin modified with Mn(3+)-tetrakis(1-methylpyridinium-4-yl)porphine exhibited the highest uricase-like activity among the modified resins tested. The fact that these resins accelerated the oxidation of uric acid even after ten cycles of use indicates that the modified resins act as catalysts in the reaction catalysed by uricase. Some of the modified resins may be effectively used for the determination of uric acid in place of uricase.

Interactions of water-soluble metalloporphyrins with nucleic acids studied by resonance Raman spectroscopy.

The resonance Raman spectra of water-soluble porphyrins, M(TMpy-P4) (M = Cu(II), Ni(II) and Co(III] and their mixtures with poly(dG-dC)2, poly(dA-dT)2 and calf thymus and salmon DNAs were measured using a divided rotating cell to determine the magnitudes of frequency shift and intensity variation resulting from M(TMpy-P4)-nucleic acid interactions. Bands II(C beta-H bending, approximately 1100 cm-1) and VIII(C beta-C beta stretch, approximately 1570 cm-1) show a large and small upward shift, respectively, when Cu(TMpy-P4) and Ni(TMpy-P4) are intercalated at the G-C sites. In contrast, these bands show a small upward and downward shift, respectively, when Co(TMpy-P4) is groove-bound at the A-T sites of nucleic acids. Both Bands V (approximately 1260 cm-1) and IX (approximately 1646 cm-1) which originate in the N-methylpyridyl group always show small downward shifts due to coulombic interaction between the N-CH3+ group of TMpy-P4 and the PO2 group of the nucleic acid.

Determination of hydrogen peroxide with N,N-diethylaniline and 4-aminoantipyrine by use of an anion-exchange resin modified with manganese-tetrakis(sulphophenyl)porphine, as a substitute for peroxidase.

Amberlite IRA 900 anion-exchange resin modified with manganese-tetrakis(sulphophenyl)-porphine has been used as a catalyst instead of peroxidase for the determination of hydrogen peroxide by the reaction 2H(2)O(2) + N,N-diethylaniline + 4-aminoantipyrine (catalyst)--> quinonoid dye (lambda(max) 550 nm) + 4H(2)O. The apparent molar absorptivity for hydrogen peroxide was 1.1 x 10(4) 1.mole(-1).cm(-1), coefficient of variation 0.7%. This value is approximately 84% of that obtained by the use of peroxidase as catalyst. Similar conditions to those in the enzymatic reaction were suitable for use of the modified resin as catalyst, and the results show it to be a good substitute for peroxidase in this reaction system.