Document Detail

Degradation of keratan sulphate by beta-N-acetylhexosaminidases A and B.
MedLine Citation:
PMID:  6458277     Owner:  NLM     Status:  MEDLINE    
Enzymic cleavage of beta-N-acetylglucosamine residues of keratan sulphate was studied in vitro by using substrate a [3H]glucosamine-labelled desulphated keratan sulphate with N-acetylglucosamine residues at the non-reducing end. Both lysosomal beta-N-acetylhexosaminidases A and B are proposed to participate in the degradation of keratan sulphate on the basis of the following observations. Homogenates of fibroblasts from patients with Sandhoff disease, but not those from patients with Tay--Sachs disease, were unable to release significant amounts of N-acetyl[3H]glucosamine. On isoelectric focusing of beta-N-acetylhexosaminidase from human liver the peaks of keratan sulphate-degrading activity coincided with the activity towards p-nitrophenyl beta-N-acetylglucosaminide. A monospecific antibody against the human enzyme reacted with both enzyme forms and precipitated the keratan sulphate-degrading activity. Both isoenzymes had the same apparent Km of 4mM, but the B form was approximately twice as active as the A form when compared with the activity towards a chromogenic substrate. Differences were noted in the pH--activity profiles of both isoenzymes. Thermal inactivation of isoenzyme B was less pronounced towards the polymeric substrate than towards the p-nitrophenyl derivative.
T Ludolph; E Paschke; J Glössl; H Kresse
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Biochemical journal     Volume:  193     ISSN:  0264-6021     ISO Abbreviation:  Biochem. J.     Publication Date:  1981 Mar 
Date Detail:
Created Date:  1982-01-09     Completed Date:  1982-01-09     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  811-8     Citation Subset:  IM    
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MeSH Terms
Cells, Cultured
Fibroblasts / enzymology
Glycosaminoglycans / metabolism*
Hexosaminidases / immunology,  metabolism*
Isoelectric Focusing
Keratan Sulfate / metabolism*
Skin / enzymology
Reg. No./Substance:
0/Glycosaminoglycans; 9056-36-4/Keratan Sulfate; EC 3.2.1.-/Hexosaminidases; EC

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

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