Linked Life Data

3138240

Source:http://linkedlifedata.com/resource/pubmed/id/3138240

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
27
pubmed:dateCreated
1988-10-19
pubmed:abstractText
NMR spectroscopy of 13C-labeled human low density lipoprotein (LDL) has been employed to characterize the lysine (Lys) residues in apo B-100. Reductive methylation with [13C]formaldehyde converts up to two-thirds of the Lys to the dimethylamino derivative; this pool of Lys is exposed at the surface of the LDL particle. The [13C]dimethyl-Lys which are visualized exhibit resonances at chemical shifts of 42.8 and 43.2 ppm (pH 7.6) indicating that they exist in two different microenvironments; this is a reflection of the native conformation of apo B associated with lipid, because the labeled, reduced, and alkylated protein gives a single resonance when dissolved in 7 M guanidine hydrochloride. The pH dependences of the Lys chemical shifts indicate that the two types of Lys titrate with different pK values; "active" Lys have a pK of 8.9, while "normal" Lys have a pK of 10.5. About 53 active Lys and 172 normal Lys are exposed on the surface of LDL with the remaining 132 Lys which are present in the human apo B-100 molecule being buried and unavailable for methylation. Addition of paramagnetic ions indicates that the active and normal Lys have different exposures to the aqueous phase; apparently this is a reflection of folding of the apo B molecule. The relative involvement of active and normal Lys in binding of apo B-100 to the LDL receptor on fibroblasts was explored by measuring the decrease in receptor binding as a function of the degree of methylation of the two types of Lys. Upper limits of 21 active and 31 normal Lys in the entire apo B-100 molecule are involved in the binding of LDL to the receptor. It is likely that these Lys are located in domains of apo B which contain clusters of basic amino acid residues and also bind heparin. If the sequence corresponding to apo B-48 (residues 1-2151) which does not bind to the receptor is excluded, then the above limits are halved; an upper limit of 10 active Lys may be particularly involved in receptor binding.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
263
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
13831-8
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed-meshheading:3138240-Apolipoprotein B-100, pubmed-meshheading:3138240-Apolipoproteins B, pubmed-meshheading:3138240-Chemical Phenomena, pubmed-meshheading:3138240-Chemistry, pubmed-meshheading:3138240-Circular Dichroism, pubmed-meshheading:3138240-Electrophoresis, Polyacrylamide Gel, pubmed-meshheading:3138240-Ferricyanides, pubmed-meshheading:3138240-Formaldehyde, pubmed-meshheading:3138240-Humans, pubmed-meshheading:3138240-Hydrogen-Ion Concentration, pubmed-meshheading:3138240-Lipoproteins, LDL, pubmed-meshheading:3138240-Lysine, pubmed-meshheading:3138240-Magnetic Resonance Spectroscopy, pubmed-meshheading:3138240-Methylation, pubmed-meshheading:3138240-Peptide Fragments, pubmed-meshheading:3138240-Receptors, LDL, pubmed-meshheading:3138240-Structure-Activity Relationship, pubmed-meshheading:3138240-Thrombin
pubmed:year
1988
pubmed:articleTitle
A 13C NMR characterization of lysine residues in apolipoprotein B and their role in binding to the low density lipoprotein receptor.
pubmed:affiliation
Department of Physiology and Biochemistry, Medical College of Pennsylvania, Philadelphia 19129.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.