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The inactivation of aspartate aminotransferase in the course of the incubation with L-serine O-sulfate is protected by thiosulfate. It has been found that also L-cysteine sulfinic acid is an inactivator when it is incubated with the enzyme, while L-serine-O-phosphate and L-cysteine-S-sulfonate are inactive. The inactivation by L-cysteine sulfinic acid is increased by the simultaneous addition of 2-oxoglutrate and is protected by thiosulfate. Cysteine-S-sulfonate has been detected in the incubates of the enzyme with L-serine-O-sulfate protected with thiosulfate. It has been concluded that the protection by thiosulfate is due to the β-addition of thiosulfate to the inactivator aminoacrylic acid. The resulting cysteine-S-sulfonate thus represents an inactive dead-end product formed in the course of the protection by thiosulfate. It is suggested that this reaction could play the role of protecting enzymes sensitive to aminoacrylic acid and of inserting inorganic sulfur into aminoacrylic acid, producing a cysteine derivative. [ABSTRACT FROM AUTHOR]

The substrate specificity of pantethinase, the mammalian enzyme which has been isolated from horse kidney cortex, has been studied. The real substrate has been found to be pantetheine in the reduced form, and the involvement of one or more —SH groups of the enzyme is also considered. A number of other compounds, chemically related to pantetheine, has also been tested as substrates. Pantethinase is able to metabolise pantetheine-4′-phosphate, with an activity about 10% of that exhibited for pantetheine; it is inactive on the other substances tested (pantothenoyl- cysteine-4′-phosphate, pantothenoylcysteine, pantetheine thiazoline, CoA). The metabolic role of pantethinase seems to be, in the light of the above results, connected with a degradative pathway of pantethcine-4′-phosphate, which is known to be one of the intermediates in the biosynthesis of CoA. [ABSTRACT FROM AUTHOR]

Cysteamine oxygenase has been further purified to a degree where it appeared homogeneous in disc gel electrophoresis. The purified enzyme possesses a molecular weight of 52000 when it is treated with either 8 M urea or with 0.1 % sodium dodecyl sulfate, The molecular weight of the native undissociated enzyme was 96000 when determined by dextran gel filtration and 92000 when determined by sedimentation equilibrium in the ultracentritfuge. These results are consistent with the occurrence of two similar subunits in the molecule of cysteamine oxygenase. [ABSTRACT FROM AUTHOR]

The addition of sodium sulfide to disulfide-containing proteins disolved in 0.01 N NaOH produces an absorption in the range of 320-350 nm similar to that exhibited by cystine or eystamine treated under the same conditions. Proteins free of cystine and cysteine and proteins containing disulfide bonds which have been reduced with sodium borohydride do not produce this .absorbance. Urea and guanidine at 6 M concentration increase the rate of production of the absorbance while sodium dodecyl sulfate at concentration of 0.02 M has an inhibitory effect both on the rate and the extent of the absorbance. The effect of pH, concentration of reagents and of the additions of cyanide and hypotaurine has been studied. The 320-350 nm absorbance as been related to the production of persulfide groups (R-SSH) as a result of the cleavage of disulfide bonds by sulfide. Attempts to prepare a purified model protein containing persulfide groups have failed owing to the instability of the persulfide group in conditions far from those used for its preparation. [ABSTRACT FROM AUTHOR]

Cysteamine oxygenase has been analysed for the presence of metals, by spectrographic analysis, and X-ray fluorescence. Iron, copper, and zinc have been found in the enzyme in the quantity accounting for 1 atom of each metal per molecule of enzyme. Passage of the enzyme through a chelating resin column did not appreciable change the specific activity but the metal content was decreased below the value of one atom per molecule of enzyme. Possible explanations for this finding are suggested. The effect of several chelating agents on enzymic activity has been studied. All the chelating agents assayed were found inhibitory when tested in suitable concentration. The highest inhibition was observed with 8-hydroxyquinoline, diethyldithiocarbamate and o-phenanthroline. KCN also was a good inhibitor. It is concluded that cysteamine oxygenase is a metal-containing enzyme and that the metals should play a functional role. [ABSTRACT FROM AUTHOR]

The results obtained with two drugs that were found to be effective against influenza virus infection in mice are reported. The two drugs are C. V. 57455 (4-biphenylylglyoxal bisulfite) and C. V. 58903 (α-oxo-α-(4-biphenylyl)-β-ethoxy-β-(4-carboxy-phenyl) amineethane). The drugs were active after administration by the subcutaneous, the oral or the nasal routes prior to and partly also 24 hours after, but not 48 hours after instillation of 5 LD of the virus. The drugs were active in low doses providing for an ample margin between the toxic and effective range. The hemagglutinin titers of the lungs of mice which died despite treatment were lower than those found in the lungs of untreated mice. The hemagglutinin titers of the lungs of surviving, unaffected, drugtreated mice were very low or undetectable. The surviving drug-treated mice were resistant to reinfection 2 to 6 weeks later. [ABSTRACT FROM AUTHOR]

1. Intrinsic fluorescences of the sulfur-transferring protein rhodanese (or thiosulfate : cyanide sulfurtransferase) and of artificially persulfurated bovine serum albumin were studied. Both are attributable mainly to tryptophan side-chains. Addition of cyanide or sulfite to these proteins causes a 20-25% increase in fluorescence. 2. Both proteins exhibit a low intensity absorption band at about 330 nm which disappears on addition of cyanide or sulfite. This absorption can be restored in rhodanese, after the treatment with cyanide, by excess thiosulfate; in the same time the fluorescence decreases to that of sulfur-containing enzyme. 3. A change in solvent viscosity, obtained by addition of glycerol, reduces the quenching effect in both proteins. On the basis of these data a long-range energy-transfer mechanism between the donor (tryptophan) and an acceptor is proposed. The acceptor involved seems to be one or more persulfide groups (R-SSH) in both proteins. 4. The presence of a persulfide group into rhodanese fits very well with the current knowledge of the mechanism of this enzyme. [ABSTRACT FROM AUTHOR]