Two major components of carbonic anhydrase were purified from porcine red cells by column chromatography and electrofocusing techniques. Both forms behaved as single components in sedimentation velocity experiments and during starch gel electrophoresis. The observed molecular weight of both forms was about 3 x lo*. On the basis of their specific COZ hydrase activities and ammo acid compositions...

Acid-base equilibria/disequilibria were evaluated in vivo in post-branchial arterial blood and pre-branchial venous blood of freshwater rainbow trout (Oncorhynchus mykiss). This was accomplished using arterial and venous extracorporeal circuits in conjunction with a stopped-flow apparatus. After the abrupt stoppage of circulating post-branchial blood within the stopped-flow apparatus, pH increa...

The reduction of cytochrome c by xanthine oxidase and the competitive inhibition of this process by carbonic anhydrase and by myoglobin have been studied by kinetic and by equilibrium binding methods. Carbonic anhydrases isolated from bovine and from human erythrocytes differed strikingly in their ability to inhibit competitively the reduction of cytochrome c. The KS for cytochrome c was a func...

The kinetics of catalysis of COZ hydration by human carbonic anhydrases B and C (EC 4.2.1.1) has been reinvestigated with use of an improved pH indicator stop-flow approach that was checked by studying the uncatalyzed rate of hydration. The Michaelis-Menten parameters were determined between pH 5.8 and 8.8 in noninhibitory buffers. For both isoenzymes K, was independent of pH, whereas V max inc...

The low-activity sulphonamide resistant isozyme of carbonic anhydrase 111 has been shown to be skeletal-muscle-specific in man (Carter et al., 1979), and preliminary experiments have demonstrated high activities of the homologous molecule in rabbit, bovine, sheep, baboon, pig, chicken, rat and mouse muscle (Jeffery & Carter, 1980). Several years ago a sulphonamide(Diamox)-resistant isoenzyme of...

The sequence of amino acid residues comprising the major form of sheep red cell carbonic anhydrase C has been determined. The primary sequences of peptides derived from cyanogen bromide cleavage and tryptic digestion were obtained primarily through the use of the Edman degradation procedure. The ordering of these peptides in the sheep molecule is based on the high degree of homology between the...

Carbonic anhydrase-azosulfonamide dissociation constants (Kd) were determined by gel filtration with high-performance liquid chromatography. By measuring the area of the elution peak at two wavelengths, Kd values were derived without having to measure a shallow trough. The procedure proved to be fast and reliable and has a general application. The dissociation constants were measured for 7-acet...

'13Cd NMR of the "3Cd(II)-substituted zinc metalloenzymes, human and bovine erythrocyte carbonic anhydrases, is reported. The high activity isozymes, human erythrocyte carbonic anhydrase, isozyme C (HCAC) and bovine erythrocyte carbonic anhydrase, isozyme B (BCAB), are characterized by relatively narrow '13Cd resonances around 220 ppm to lowfield of Cd(C104)Z. These resonances are relatively in...

The ability of rat liver zinc-thionein to donate its metal to the apo-enzymes of the zinc enzymes horse liver alcohol dehydrogenase, yeast aldolase, thermolysin, Escherichia coli alkaline phosphatase and bovine erythrocyte carbonic anhydrase was investigated. Zinc-thionein was as good as, or better than, ZnSO(4), Zn(CH(3)CO(2))(2) or Zn(NO(3))(2) in donating its zinc to these apo-enzymes. Apo-(...