Linked Life Data

9535885

Source:http://linkedlifedata.com/resource/pubmed/id/9535885

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
15
pubmed:dateCreated
1998-5-14
pubmed:abstractText
The reconstructions of an intermediate form of human alpha2-macroglobulin (half-transformed alpha2M) in which two of its four bait regions and thiol ester sites were cleaved by chymotrypsin bound to Sepharose were obtained by three-dimensional electron microscopy from stain and frozen-hydrated specimens. The structures show excellent agreement and reveal a structure with approximate dimensions of 195 (length) x 135 (width) and 130 A (depth) with an internal funnel-shaped cavity. The structure shows that a chisel-shaped body is connected to a broad base at the opposing end by four stands. Four approximately 45 A diameter large openings in the body of the structure result in a central cavity that is more accessible to the proteinase than those associated with the native or fully transformed structures. The dissimilarity in the shapes between the two ends of alpha2M half-transformed and the similarity between its chisel-shaped body and that of native alpha2M indicate that the chymotrypsin has cleaved both bait regions in the bottom-half of the structure. Consequently, its functional division lies on the minor axis. The structural organization is in accord with biochemical studies, which show that the half-transformed alpha2M migrates on native polyacrylamide gels at a rate intermediate to the native and fully transformed alpha2M and is capable of trapping 1 mol of proteinase. Even though its upper portion is similar to the native molecule, significant differences in their shapes are apparent and these differences may be related to its slower reaction with a proteinase than the native structure. These structural comparisons further support the view that the transformation of alpha2M involves an untwisting of its strands with an opening of the cavity for entrance of the proteinase and a retwisting of the strands around the proteinase resulting in its encapsulation.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
10
pubmed:volume
273
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
8987-93
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
On the structural changes of native human alpha2-macroglobulin upon proteinase entrapment. Three-dimensional structure of the half-transformed molecule.
pubmed:affiliation
Department of Pathology and Laboratory Medicine, University of Texas Medical School, Houston, Texas 77030, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't