scholarly journals Carbonic anhydrase in human platelets

1984 ◽  
Vol 217 (3) ◽  
pp. 727-730 ◽  
Author(s):  
W Siffert ◽  
G Gros
Keyword(s):  
Carbonic Anhydrase ◽  
Carbonic Anhydrase Activity ◽  
Human Platelets ◽  
Carbonic Anhydrase Ii ◽  
Affinity Column ◽  
Kinetic Properties ◽  
Km Value ◽  
Flow Apparatus ◽  
High Concentrations ◽  
Kinetics Of

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-centre activity kcat. of 130000 s-1 and an inhibition constant Ki towards ethoxzolamide of 0.3 nM. From these values, CO2 hydration inside platelets is estimated to be accelerated by a factor of 2500. When platelet lysates were subjected to affinity chromatography, only the high-activity carbonic anhydrase II could be eluted from the affinity column, whereas the carbonic anhydrase isoenzyme I, which is known to occur in high concentrations in human erythrocytes, appeared to be absent.

scholarly journals The Influence of Varying Fluorination Patterns on the Thermodynamics and Kinetics of Benzenesulfonamide Binding to Human Carbonic Anhydrase II

Biomolecules ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 509 ◽  
Author(s):  
Steffen Glöckner ◽  
Khang Ngo ◽  
Björn Wagner ◽  
Andreas Heine ◽  
Gerhard Klebe
Keyword(s):  
Carbonic Anhydrase ◽  
Carbonic Anhydrase Ii ◽  
The Novel ◽  
Binding Modes ◽  
X Ray ◽  
Structure Activity ◽  
Small Set ◽  
Novel Method ◽  
Human Carbonic Anhydrase ◽  
Kinetics Of

The fluorination of lead-like compounds is a common tool in medicinal chemistry to alter molecular properties in various ways and with different goals. We herein present a detailed study of the binding of fluorinated benzenesulfonamides to human Carbonic Anhydrase II by complementing macromolecular X-ray crystallographic observations with thermodynamic and kinetic data collected with the novel method of kinITC. Our findings comprise so far unknown alternative binding modes in the crystalline state for some of the investigated compounds as well as complex thermodynamic and kinetic structure-activity relationships. They suggest that fluorination of the benzenesulfonamide core is especially advantageous in one position with respect to the kinetic signatures of binding and that a higher degree of fluorination does not necessarily provide for a higher affinity or more favorable kinetic binding profiles. Lastly, we propose a relationship between the kinetics of binding and ligand acidity based on a small set of compounds with similar substitution patterns.

scholarly journals Microsecond Simulation Analysis of Carbonic Anhydrase – II in Complex with (+)- Cathechin Revealed Molecular Interactions Responsible for Its Amelioration Effect on Fluoride Toxicity

2020 ◽  
Author(s):  
Pulala Raghuveer Yadav ◽  
Hussain Syed ◽  
Sadam DV Satyanarayana ◽  
Pavan Kumar Pindi
Keyword(s):  
Carbonic Anhydrase ◽  
Conformational Changes ◽  
Simulation Analysis ◽  
Carbonic Anhydrase Activity ◽  
Catalytic Site ◽  
Carbonic Anhydrase Ii ◽  
Fluoride Ions ◽  
Skeletal Health ◽  
Ionic Bonds ◽  
Male Wistar Rats

Fluorosis is a chronic condition caused by overexposure to fluoride, marked by impaired dental, skeletal, and non-skeletal health. In presence of excess fluoride ions, in severe cases calcification of the ligaments observed. Earlier studies have suggested that the disruption of carbonic anhydrase activity via ionic homeostasis change was associated with F toxicity. In a recent study, it was demonstrated that Tamarind fruit extract was effective in increasing the urinary F excretion in male Wistar rats via studying the mRNA expression of carbonic anhydrase II (CA II) in kidney homogenates using western blotting, immunohistochemistry and quantitative Realtime PCR based studies. We have carried out this study to understand the detailed molecular level interactions responsible for this tamarind extract based (+)-cathechin compound towards lowering the F toxicity via targeting CA-II. From our study, it was revealed that due to the ability of (+)-cathechin compound to bind tightly filling complete available space at the catalytically important site forming metal coordinated ionic bonds with His94, His96 and His119 residues helps in restricting F ions to interact with Zn ion located at the core of catalytic site responsible for its functionality. On the other hand, interaction of (+)-cathechin compound with Gln92 was observed to be critically important towards inducing conformational changes in CA-II, thus allowing (+)-cathechin compound to burry even deeply inside the catalytic site.

Mechanism of acid adaptation of a fish living in a pH 3.5 lake

2003 ◽  
Vol 284 (5) ◽  
pp. R1199-R1212 ◽  
Author(s):  
Taku Hirata ◽  
Toyoji Kaneko ◽  
Toshihiro Ono ◽  
Takeru Nakazato ◽  
Norihisa Furukawa ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Basolateral Membrane ◽  
Single Species ◽  
Carbonic Anhydrase Ii ◽  
Chloride Cells ◽  
Apical Surface ◽  
Acidic Lake ◽  
Apical Side ◽  
High Concentrations

Despite unfavorable conditions, a single species of fish, Osorezan dace, lives in an extremely acidic lake (pH 3.5) in Osorezan, Aomori, Japan. Physiological studies have established that this fish is able to prevent acidification of its plasma and loss of Na+. Here we show that these abilities are mainly attributable to the chloride cells of the gill, which are arranged in a follicular structure and contain high concentrations of Na+-K+-ATPase, carbonic anhydrase II, type 3 Na+/H+ exchanger (NHE3), type 1 Na+-HCO[Formula: see text] cotransporter, and aquaporin-3, all of which are upregulated on acidification. Immunohistochemistry established their chloride cell localization, with NHE3 at the apical surface and the others localized to the basolateral membrane. These results suggest a mechanism by which Osorezan dace adapts to its acidic environment. Most likely, NHE3 on the apical side excretes H+ in exchange for Na+, whereas the electrogenic type 1 Na+-HCO[Formula: see text]cotransporter in the basolateral membrane provides HCO[Formula: see text] for neutralization of plasma using the driving force generated by Na+-K+-ATPase and carbonic anhydrase II. Increased expression of glutamate dehydrogenase was also observed in various tissues of acid-adapted dace, suggesting a significant role of ammonia and bicarbonate generated by glutamine catabolism.

scholarly journals Microsecond Simulation Analysis of Carbonic Anhydrase – II in Complex with (+)- Cathechin Revealed Molecular Interactions Responsible for Its Amelioration Effect on Fluoride Toxicity

2020 ◽  
Author(s):  
Pulala Raghuveer Yadav ◽  
Hussain Syed ◽  
Sadam DV Satyanarayana ◽  
Pavan Kumar Pindi
Keyword(s):  
Carbonic Anhydrase ◽  
Conformational Changes ◽  
Simulation Analysis ◽  
Carbonic Anhydrase Activity ◽  
Catalytic Site ◽  
Carbonic Anhydrase Ii ◽  
Fluoride Ions ◽  
Skeletal Health ◽  
Ionic Bonds ◽  
Male Wistar Rats

Fluorosis is a chronic condition caused by overexposure to fluoride, marked by impaired dental, skeletal, and non-skeletal health. In presence of excess fluoride ions, in severe cases calcification of the ligaments observed. Earlier studies have suggested that the disruption of carbonic anhydrase activity via ionic homeostasis change was associated with F toxicity. In a recent study, it was demonstrated that Tamarind fruit extract was effective in increasing the urinary F excretion in male Wistar rats via studying the mRNA expression of carbonic anhydrase II (CA II) in kidney homogenates using western blotting, immunohistochemistry and quantitative Realtime PCR based studies. We have carried out this study to understand the detailed molecular level interactions responsible for this tamarind extract based (+)-cathechin compound towards lowering the F toxicity via targeting CA-II. From our study, it was revealed that due to the ability of (+)-cathechin compound to bind tightly filling complete available space at the catalytically important site forming metal coordinated ionic bonds with His94, His96 and His119 residues helps in restricting F ions to interact with Zn ion located at the core of catalytic site responsible for its functionality. On the other hand, interaction of (+)-cathechin compound with Gln92 was observed to be critically important towards inducing conformational changes in CA-II, thus allowing (+)-cathechin compound to burry even deeply inside the catalytic site.

Carbonic anhydrase activity of intact carbonic anhydrase II-deficient human erythrocytes

1988 ◽  
Vol 65 (4) ◽  
pp. 1472-1480 ◽  
Author(s):  
S. J. Dodgson ◽  
R. E. Forster ◽  
W. S. Sly ◽  
R. E. Tashian
Keyword(s):  
Carbonic Anhydrase ◽  
Normal Subjects ◽  
Relative Difference ◽  
Carbonic Anhydrase Activity ◽  
Carbonic Anhydrase Ii ◽  
Normal Cells ◽  
Reaction Velocity ◽  
Fractional Reduction ◽  
Lower Temperature ◽  
Exchange Technique

Intact erythrocytes from subjects with deficiency of blood carbonic anhydrase (CA) II and from normal subjects were assayed for enzyme activity by use of an 18O exchange technique in a solution containing 25 mM (CO2 + NaHCO3) plus 125 mM NaCl. At 25 degrees C and pH 7.4, the catalyzed reaction velocity was 0.32 +/- 0.04 M/s for the CA II-deficient and 1.60 +/- 0.12 M/s for the normal cells, a ratio of 1:5. Under the same conditions at 37 degrees C the relative difference between the CA II-deficient and normal cells was much less: the velocity for the CA II-deficient cells was 0.84 +/- 0.07 M/s and for the normal cells 1.60 +/- 0.32 M/s, a ratio of 1:1.9. Results were comparable for the hemolysates with the NaHCO3 reduced to 85 mM (the corresponding intracellular concentration): at 25 degrees C CA II-deficient cells had a velocity of 0.36 +/- 0.01 M/s compared with 1.12 +/- 0.04 M/s for the normal cells, a ratio of 1:3.1. At 37 degrees C again the relative difference between hemolysates from CA II normal and deficient cells was much less: the CA II-deficient cells had a reaction velocity of 1.17 +/- 0.22 M/s vs. 2.60 +/- 0.36 M/s for the normal cells, a ratio of 1:2.2. The greater fractional reduction of enzyme velocity of CA II-deficient cells at 25 degrees C compared with 37 degrees C appears to be explained by a greater chloride inhibition of the presumed CA I at the lower temperature.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Intracellular Binding/Unbinding Kinetics of Approved Drugs to Carbonic Anhydrase II Observed by in-Cell NMR

2020 ◽  
Vol 15 (10) ◽  
pp. 2792-2800
Author(s):  
Enrico Luchinat ◽  
Letizia Barbieri ◽  
Matteo Cremonini ◽  
Alessio Nocentini ◽  
Claudiu T. Supuran ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Carbonic Anhydrase Ii ◽  
Intracellular Binding ◽  
Approved Drugs ◽  
Kinetics Of
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