Linked Life Data

10833408

Source:http://linkedlifedata.com/resource/pubmed/id/10833408

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2000-8-14
pubmed:abstractText
alpha-N-Acetylglucosaminidase (EC 3.2.1.50) is a lysosomal enzyme that is deficient in the genetic disorder Sanfilippo syndrome type B. To study the human enzyme, we expressed its cDNA in Lec1 mutant Chinese hamster ovary (CHO) cells, which do not synthesize complex oligosaccharides. The enzyme was purified to apparent homogeneity from culture medium by chromatography on concanavalin A-Sepharose, Poros 20-heparin, and aminooctyl-agarose. The purified enzyme migrated as a single band of 83 kDa on SDS-PAGE and as two peaks corresponding to monomeric and dimeric forms on Sephacryl-300. It had an apparent K(m) of 0.22 mM toward 4-methylumbelliferyl-alpha-N-acetylglucosaminide and was competitively inhibited by two potential transition analogs, 2-acetamido-1,2-dideoxynojirimycin (K(i) = 0.45 microM) and 6-acetamido-6-deoxycastanospermine (K(i) = 0.087 microM). Activity was also inhibited by mercurials but not by N-ethylmaleimide or iodoacetamide, suggesting the presence of essential sulfhydryl residues that are buried. The purified enzyme preparation corrected the abnormal [(35)S]glycosaminoglycan catabolism of Sanfilippo B fibroblasts in a mannose 6-phosphate-inhibitable manner, but its effectiveness was surprisingly low. Metabolic labeling experiments showed that the recombinant alpha-N-acetylglucosaminidase secreted by CHO cells had only a trace of mannose 6-phosphate, probably derived from contaminating endogenous CHO enzyme. This contrasts with the presence of mannose 6-phosphate on naturally occurring alpha-N-acetylglucosaminidase secreted by diploid human fibroblasts and on recombinant human alpha-l-iduronidase secreted by the same CHO cells. Thus contrary to current belief, overexpressing CHO cells do not necessarily secrete recombinant lysosomal enzyme with the mannose 6-phosphate-targeting signal; this finding has implications for the preparation of such enzymes for therapeutic purposes.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
1046-5928
pubmed:author
pubmed:copyrightInfo
Copyright 2000 Academic Press.
pubmed:issnType
Print
pubmed:volume
19
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
202-11
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Purification and characterization of recombinant human alpha-N-acetylglucosaminidase secreted by Chinese hamster ovary cells.
pubmed:affiliation
Department of Biological Chemistry, University of California, Los Angeles 90095-1737, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't