Linked Life Data

15271520

Source:http://linkedlifedata.com/resource/pubmed/id/15271520

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
2004-7-23
pubmed:databankReference
pubmed:abstractText
Lactoferrin (Lf) is a mammalian iron binding protein present in external secretions and in polymorphonuclear leukocytes. Its role in host defense mechanisms related to the non-immune defense system has been definitively established. Lf has two identical iron-binding sites, far from each other (44.3 A) and magnetically non-interacting. Fe(III) ions are six-coordinated, with four donor atoms provided by protein sidechains (two Tyr, one His, one Asp) and two oxygen atoms from a bridged HCO(3)(-). This set of ligands provides an ideal coordination scheme for stable and reversible iron binding. Nuclear magnetic relaxation dispersion (NMRD) profiles of Lf are consistent with a closest distance for a single water hydrogen atom of 3.1 A. By looking at the X-ray structure of Lf (PDB ID code: 1BLF) we can locate two water oxygens at 3.95 and 4.27 A from each Fe(III), respectively. Temperature dependence data suggest that an important contribution to the overall paramagnetic contribution to the solvent water relaxation rate arises from one or more second sphere water molecules in slow exchange with the bulk. A decreasing value of the exchange rate is obtained, ranging from 1.2 to 0.7 micros in the observed temperature range (25-65 degrees C), with an activation enthalpy of 7.3+/-0.8 kJ mol(-1). The low exchange rate obtained from NMRD data can be explained by the observation that both water molecules are bound to several polar groups of the protein backbone and side chains. By increasing the pH from 6.5 to 12 two distinct titrations are observed, consistent with sequential removal of both water molecules.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0162-0134
pubmed:author
pubmed:issnType
Print
pubmed:volume
98
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1421-6
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
1H NMR relaxometric characterization of bovine lactoferrin.
pubmed:affiliation
Dipartimento di Biologia Strutturale e Funzionale, Università dell'Insubria, Via Alberto da Giussano 12, I-21052 Busto Arsizio (VA), Italy. mauro.fasano@uninsubria.it
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't