The effect of calcitonin (CT) and parathyroid hormone (PTH) on carbonic anhydrase (carbonate hydrolyase, EC 4.2.1.1.) activity was tested in human erythrocyte hemolysates and with purified carbonic anhydrases I and II. The most important effect was on carbonic anhydrase II: CT showed a 2-fold increase and PTH showed a 50% decrease of carbonic anhydrase activity. This effect was observed at low ...

A physiologically significant level of intracellular carbonic anhydrase has been idenfified in Chlamydomonas reinhardtii after lysis of the cell wall-less mutant, cw15, and two intracellular polypeptides have been identified which bind to anti-carbonic anhydrase antisera. The susceptibility of the intracellular activity to sulfonamide carbonic anhydrase inhibitors is more than three orders-of-m...

Present understanding of gene expression in erythropoietic tissues is derived solely from studies of the globin genes. Of the three distinct carbonic anhydrase (carbonate dehydratase; carbonate hydro-lyase, EC 4.2.1.1) isozymes, carbonic anhydrase I is erythrocyte-specific and, in humans, is under developmental control. The appearance of carbonic anhydrase I in the erythrocyte late in fetal lif...

A series of benzimidazo[1,2-c][1,2,3]thiadiazole-7-sulfonamides were synthesized and their binding to two carbonic anhydrase isozymes measured by isothermal titration calorimetry (ITC). Human carbonic anhydrase I (hCAI) and bovine carbonic anhydrase II (bCAII) bound the inhibitors with observed association constants in the range from 1.1 x 10(6) to 2.6 x 10(7) M(-1).

It has been demonstrated that parathyroid hormone (PTH) inhibits the proximal tubular reabsorption of bicarbonate, and increases the urinary excretion of that ion. There is also a qualitative similarity between the alterations of the proximal tubular reabsorption of phosphate, sodium, and water after PTH administration and after acetazolamide administration. These findings suggest that the rena...

The carbonic anhydrase activity of human platelets was investigated by measuring the kinetics of CO2 hydration in supernatants of platelet lysates by using a pH stopped-flow apparatus. An average carbonic anhydrase concentration of 2.1 microM was determined for pellets of human platelets. Analysis of the kinetic properties of this carbonic anhydrase yielded a Km value of 1.0 mM, a catalytic-cen...

Gel permeation chromatography was used to fractionate zinc-bound constituents in haemolysates of human blood samples. The zinc content of the fractions was determined by electrothermal atomic absorption spectrometry. The zinc-containing enzyme, carbonic anhydrase, was identified by isoelectric focusing. A fraction of more than 0.9 of the zinc eluted from the column was bound to the carbonic anh...

1. Carbonic anhydrase was measured in tissues of silkmoths, Hyalophora cecropia, reared on either a wheatgerm-based synthetic diet or wild cherry foliage in feeding fifth-instar larvae, throughout the larval-pupal transformation and in newly ecdysed pupae. 2. Carbonic anhydrase activity was present in fat body, midgut and intgeumentary epithelial cells, but not in haemolymph, cuticle or the int...

alpha-Crystallin, a multimeric protein, exhibits chaperone-like activity in preventing aggregation of several proteins. We have studied the chaperone-like activity of alpha-crystallin toward heat-induced aggregation of bovine and human carbonic anhydrase. Human carbonic anhydrase aggregates at 60 degrees C, while bovine carbonic anhydrase does not aggregate significantly at this temperature. Re...

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...