Low Carbonic Anhydrase Activity Research Articles

Deficiency of a carbonic anhydrase (CAI) isoenzyme in the chinchilla.

Summary1. A marked deficiency of the low activity carbonic anhydrase isoenzyme (CAI) has been found in chinchillas, resulting in a 90% reduction in CAI.2. The trace of CAI found in deficient animals exhibits a similar immunological reaction and electrophoretic migration to the usual CAI (+).

Carbonic anhydrase isonenzymes in infants with respiratory distress syndrome

Carbonic anhydrase (CA), a zinc metalloenzyme existing in several isoenzymic forms, is involved in CO2 transport at the cellular and pulmonary levels. Previously we reported (N. Engl. J. Med. 277:1t57, 1967) that infants with respiratory distress syndrome (RDS) had lower cord blood CA activity than infants without RDS. The present study includes a larger number of premature infants (104) to distinguish between the low CA due to immaturity or to RDS. Cord red blood cell CA activity increased with gestational age but at all stages of maturity infants with RDS had lower CA activity than similar infants without RDS (p ~ 0.05 for all gestational age groups). CA isoenzymes B and C (CA-B and CA-C) increased with maturation but were lower in infants with than without RDS (p ~ 0.05). Specific activities (enzyme activity/enzyme protein) of CA-B and CA-C were the same for infants with RDS, normal infants, and adults indicating that the low CA activity in infants with RDS is not due to CA inhibitors or abnormal types of CA but to diminished enzyme protein. Total red blood cell zinc was the same for all newborn infants but the ratio, red blood cell zinc/CA protein, was higher for infants with RDS (p ~ 0.05) than any others. This could be due to either: (a) inability to incorporate zinc into CA molecule, (b) an abnormal zinc metalloprotein, or (c) a defect in CA protein synthesis after zinc incorporation into CA precursor. COValENT. Carbonic anhydrase activity was measured using the carbon dioxide hydration reaction; isoenzymes of carbonic anhydrase were identified by immunochemical techniques. Carbonic anhydrase activity is not inhibited by elevated Pco~ or by acidosis. The relationship between carbonic anhydrase activity and the age of the red cell is unknown. As a group, newborn infants with R D S who died had lower carbonic anhydrase activity than infants who survived. However, deaths were more frequent in infants of shorter gestational age, who were the infants who also had lower carbonic anhydrase activity. Within given gestational age periods the number of infants who died was too small to permit statistical comparison. In older children with elevation of Pco2, decreased carbonic anhydrase activity has not been demonstrated.

Properties of Carbonic Anhydrase Isozymes Isolated from Porcine Erythrocytes

Abstract 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 104. On the basis of their specific CO2 hydrase activities and amino acid compositions, these two carbonic anhydrase isozymes were designated as high activity (carbonic anhydrase C) or low activity (carbonic anhydrase B) forms which appear to be homologous to the high and low activity carbonic anhydrases, respectively, of other mammals. When these pig B and C isozymes were compared with the red cell carbonic anhydrases of other ungulates (cattle and horse), several interesting features were observed. In contrast to the electrophoretic gel patterns of the horse B and C isozymes in which the C form is markedly more basic than the B form, the high activity C form of pig was observed to be more acidic than the low activity B form. The tryptic peptide map of bovine carbonic anhydrase appears to be more similar to that of porcine carbonic anhydrase C than to B, indicating that they are probably homologous proteins. Neoprontosil binding by the pig and horse B isozymes give rise to essentially identical spectra in the 425- to 600-mµ region, whereas the C isozymes, from these two sources, generate quite different spectra.

CO2Compensation Concentration, Rate of Photosynthesis, and Carbonic Anhydrase Activity of Plants

Leaves of a number of plant species were surveyed for their CO2compensation concentration which is one of the distinguishing characteristics used to classify plants on the basis of their photosynthetic capacity. Monocot genera with low CO2compensation values are mainly limited to tribes of Chlorideae, Paniceae, Andropogoneae, Tripsaceae, and a part of Festuceae in Gramineae. Major grain crops, except corn (Zea maysL.) and sorghum (Sorghum vulgarePers.), are primarily in the tribes of Hordeae, Aveneae, and Oryzeae, and have high CO2compensation concentrations. Seven genera of dicots with low CO2compensation occur in the four families of Amaranthaceae, Chenopodiaceae, Portulacaceae, and Euphorbiaceae. Major dicot crops are in the families Leguminosae and Malvaceae and have high CO2compensation points. Low CO2compensation concentration also is correlated with low carbonic anhydrase activity. Conversely, high CO2compensation concentration plants have a high carbonic anhydrase activity. Data on the influence of light intensity and temperature on the rate of photosynthetic CO2fixation in leaves from plants with high and low CO2compensation concentration indicate differential responses of photosynthesis to these environmental factors. The data are interpreted as supporting a hypothesis for competition by specific plants.

Localization of carbonic anhydrase in the nervous system.

Single-cell analyses of carbonic anhydrase demonstrate that this enzyme is selectively concentrated in the glial and choroid cells of the rat brain. The nerve cells show a very low carbonic anhydrase activity. This specific localization supports the view that glial carbonic anhydrase is implicated in a mechanism for the active transport of chloride from the capillaries to the interstitial and cerebrospinal fluids.

Studies on carbonic anhydrase activity in children. II. Possibilities of influencing the carbonic anhydrase activity in the blood of premature infants

Summary An account of the results of intravenous and intramuscular injections of whole blood, plasma and serum into premature infants is given. In all cases there is an increase of carbonic anhydrase activity in the infant's blood. The cause for the increase in enzyme activity is discussed. This is found to be probably due to an activating factor in plasma; this factor is thermostable, dialysable and seemingly of non‐electrolyte character. The possible inconveniences that premature infants could suffer on account of their low carbonic anhydrase activity and the help possibly afforded to these infants by transfusions are discussed.

Studies on carbonic anhydrase activity in children. 1. Enzyme activity in the blood of infants and children of different ages, particularly in premature infants.

Summary A short review of the literature on the enzyme earbonic anhydrase is given. Special weight has been laid on earlier clinical work. An account of the author's method, which is a modification of the “boat method” of Meldrum and Roughton, is given. A number of normal values for the C.a. activity in the blood of adults, children in various age groups and infants are given. It is concluded, that the activity for new‐born infants is about one third that of adults, and that the enzyme activity in infants and children increases with increasing age. The enzyme activity in the blood of premature infants is shown to be only about 5–10 per cent that of adults. The activity increases slowly during the first months of life. The relationships between the enzyme activity and the degree of maturity, length and weight at birth are discussed. There seems to be a good correlation between enzyme activity and maturity. The clinical importance of the low enzyme activity for cyanosis and vitality in premature infants is discussed. The author has not been able to verify the finding of Stevenson, that cyanosis often is associated with low carbonic anhydrase activity. A parallel relationship between the enzyme activity and the zinc content of the blood is demonstrated.