The relationship of sulfhydryl and disulfide groups to protein synthesis in normal and rapidly growing tissues was investigated by quantitation of sulfhydryl groups in endoplasmic reticulum and polyribosomes of normal liver and hepatomas. Stripping by ethylenediaminetetraacetate and potassium chloride of normal liver smooth and rough endoplasmic reticulum reduced by 15 percent and increased 30 ...

Site-directed mutagenesis of the katE gene of Escherichia coli was used to change, individually and in combination, Cys438 and Cys669 to serine in catalase HPII. The Cys438-->Ser mutation caused a 30% reduction in the specific activity of the enzyme, whereas the Cys669-->Ser mutation did not affect enzyme activity. The titration of free sulfhydryl groups in HPII revealed that Cys669 was reactiv...

The rate of quenching by Ehrlich ascites cells of anionic 2,6-dimethoxy-p-semiquinone and ascorbyl free radicals is investigated as a function of cell concentration, the blocking of cell-surface sulfhydryl groups by N-ethylmaleimide, and the reduction of cell-surface charge by neuraminidase. The rate of quenching is found to be proportional to cell viability and to the number of free cell-surfa...

An experiment was conducted to study the biochemical and physicochemical changes with respect to improvement in tenderness of spent hen breast meat. Breast muscle obtained from freshly slaughtered spent hens (72 wk old) was divided into 5 equal lots and dipped in 1 mM NaN3 before being packed in low-density polyethylene pouches under aerobic conditions and stored at refrigeration temperature (4...

Sulfhydryl groups of ovalbumin were chemically modified under denaturing conditions in the absence and presence of dithiothreitol, and effects on the secondary structure of the protein were investigated by circular dichroic (CD) measurements. The contents of alpha-helix, beta-structure, and "random coil" (unordered, nonrepetitive structure) were estimated by simulation of the CD spectra and usi...

An initial rate approach was used to study the reaction of peroxynitrite with human serum albumin (HSA) through stopped-flow spectrophotometry. At pH 7.4 and 37 degreesC, the second order rate constant for peroxynitrite reaction with HSA was 9.7 +/- 1.1 x 10(3) M-1 s-1. The rate constants for sulfhydryl-blocked HSA and for the single sulfhydryl were 5.9 +/- 0.3 and 3.8 +/- 0.8 x 10(3) M-1 s-1, ...

A subunit structure for human superoxide dismutase has been demonstrated by sedimentation equilibrium, agarose gel filtration, and sodium dodecyl sulfate polyacrylamide gel electrophoretic studies. This protein appears to be composed of 2 subunits, not linked by covalent bonds, each with a molecular weight about 16,000. Dissociation of the subunits is facilitated by alkylation of the two sulfhy...

The contractile response of rabbit renal arteries and canine tibial arteries to prostaglandins A2, B2, F2alpha, E1, E2, D2, and B1 was associated with a reduction in total sulfhydryl group content of smooth muscle. The total sulfhydryl content of rabbit renal and canine tibial arteries and was not affected by norepinephrine or potassium chloride. Reduction of disulfide groups with dithiothreito...