Document Detail

A facilitative role for carbonic anhydrase activity in matrix vesicle mineralization.
MedLine Citation:
PMID:  7950506     Owner:  NLM     Status:  MEDLINE    
Carbonic anhydrase (CA) which catalyzes the reversible hydrolysis of carbon dioxide is known to be important in osteoclastic bone resorption, however, suggested roles in calcium phosphate mineral formation have not been previously demonstrated. Biochemical evidence is provided for the presence of CA in growth plate matrix vesicles (MV) and the level of activity determined by enzyme assay. Inhibition of CA activity with the specific inhibitor acetazolamide resulted in reduced rates of MV mineralization. Other inhibitor studies showed that MV mineralization was also impaired by 4,4-diisothiocyanatostilbene-2, 2-disulfonic acid (DIDS), a blocker of membrane bicarbonate channels. No evidence was found for the presence of any proton pumps or channels. When acetazolamide and DIDS were combined, their inhibitory effects on MV mineralization were additive. These findings suggest that MV possess a pH regulation system composed of carbonic anhydrase and a putative bicarbonate channel. This system may function in the MV by providing intraluminal buffering capacity. The control of intravesicular pH is important for the stabilization of the acid-labile nucleational core complex and in preventing the build-up of protons during calcium phosphate phase transformations.
G R Sauer; B R Genge; L N Wu; J E Donachy
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Bone and mineral     Volume:  26     ISSN:  0169-6009     ISO Abbreviation:  Bone Miner     Publication Date:  1994 Jul 
Date Detail:
Created Date:  1994-12-23     Completed Date:  1994-12-23     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8610542     Medline TA:  Bone Miner     Country:  IRELAND    
Other Details:
Languages:  eng     Pagination:  69-79     Citation Subset:  IM; S    
Department of Chemistry and Biochemistry, University of South Carolina, Columbia 29208.
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MeSH Terms
4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / pharmacology
Acetazolamide / pharmacology
Blotting, Western
Calcification, Physiologic*
Carbonic Anhydrases / metabolism*
Electrophoresis, Polyacrylamide Gel
Growth Plate / enzymology,  metabolism*
Hydrogen-Ion Concentration
Intracellular Membranes / metabolism
Microsomes / metabolism
Grant Support
Reg. No./Substance:
53005-05-3/4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; 59-66-5/Acetazolamide; EC Anhydrases

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