Document Detail


A bound form of silicon in glycosaminoglycans and polyuronides.
MedLine Citation:
PMID:  4268099     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Silicon was found to be a constituent of certain glycosaminoglycans and polyuronides, where it occurs firmly bound to the polysaccharide matrix. 330-554 ppm of bound Si were detected in purified hyaluronic acid from umbilical cord, chondroitin 4-sulfate, dermatan sulfate, and heparan sulfate. These amounts correspond to 1 atom of Si per 50,000-85,000 molecular weight or 130-280 repeating units. 57-191 ppm occur in chondroitin 6-sulfate, heparin, and keratan sulfate-2 from cartilage, while hyaluronic acids from vitreous humor and keratan sulfate-1 from cornea were Si-free. Large amounts of bound Si are also present in pectin (2580 ppm) and alginic acid (451 ppm). The bound Si is not dialyzable, does not react with ammonium molybdate, is not liberated by autoclaving or 8 M urea, and is stable against weak alkali and acid. Strong alkali and acid hydrolyze the Si-polysaccharide bond. Free, direct-reacting, dialyzable silicate is obtained. Enzymatic hydrolysis of hyaluronic acid or pectin does not liberate silicic acid, but leads to products of low molecular weight still containing Si in bound form. It is concluded that Si is present as a silanolate, i.e., an ether (or esterlike) derivative of silicic acid, and that R(1)-O-Si-O-R(2) or R(1)-O-Si-O-Si-O-R(2) bridges play a role in the structural organization of glycosaminoglycans and polyuronides. Thus, Si may function as a biological crosslinking agent and contribute to architecture and resilience of connective tissue.
Authors:
K Schwarz
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  70     ISSN:  0027-8424     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  1973 May 
Date Detail:
Created Date:  1973-08-10     Completed Date:  1973-08-10     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1608-12     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Binding Sites
Cartilage / analysis
Cattle
Chondroitin / analysis
Colorimetry
Dextrans / analysis
Dialysis
Fishes
Glycogen / analysis
Glycosaminoglycans / analysis*
Heparin / analysis
Humans
Hyaluronic Acid / analysis
Hydrolysis
Inulin / analysis
Methods
Molecular Weight
Pectins / analysis
Polymers / analysis
Silicon / analysis*
Spectrophotometry
Starch / analysis
Umbilical Cord / analysis
Urea / pharmacology
Uronic Acids / analysis*
Chemical
Reg. No./Substance:
0/Glycosaminoglycans; 0/Pectins; 0/Polymers; 0/Uronic Acids; 57-13-6/Urea; 7440-21-3/Silicon; 9004-54-0/Dextrans; 9004-61-9/Hyaluronic Acid; 9005-25-8/Starch; 9005-49-6/Heparin; 9005-79-2/Glycogen; 9005-80-5/Inulin; 9007-27-6/Chondroitin
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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