Linked Life Data

10600111

Source:http://linkedlifedata.com/resource/pubmed/id/10600111

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
50
pubmed:dateCreated
2000-1-19
pubmed:abstractText
Cd-substituted forms of the Bacillus cereus metallo-beta-lactamases (BCII) were studied by perturbed angular correlation of gamma-rays (PAC) spectroscopy. At very low [Cd]:[apo-beta-lactamase] ratios, two nuclear quadrupole interactions (NQI) were detected. For [Cd]:[apo-beta-lactamase] ratios between 0.8 and 3.0, two new NQIs appear, and the spectra show that up to 2 cadmium ions can be bound per molecule of apoenzyme. These results show the existence of two interacting Cd-binding sites in BCII. The relative populations of the two NQIs found at low [Cd]:[apo-beta-lactamase] ratios yielded a 1:3 ratio for the microscopic dissociation constants of the two different metal sites (when only one cadmium ion is bound). X-ray diffraction data at pH 7.5 demonstrate that also for Zn(II) two binding sites exist, which may be bridged by a solvent molecule. The measured NQIs could be assigned to the site with three histidines as metal ligands (three-His site) and to the site with histidine, cysteine, and aspartic acid as metal ligands (Cys site), respectively, by PAC measurements on the Cys168Ala mutant enzyme. This assignment shows that cadmium ions preferentially bind to the Cys site. This is in contrast to the preference of Zn(II) in the hybrid Zn(II)Cd(II) enzyme, where an analysis of the corresponding PAC spectrum showed that Cd(II) occupied the Cys site, whereby Zn(II) occupied the site with three histidines. The difference between Zn(II) and Cd(II) in affinity for the two sites is combined with the kinetics of hydrolysis of nitrocefin for different metal ion substitutions (Zn(2)E, ZnE, Cd(2)E, CdE, and ZnCdE) to study the function of the two metal ion binding sites.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
14
pubmed:volume
38
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
16500-6
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Preference of Cd(II) and Zn(II) for the two metal sites in Bacillus cereus beta-lactamase II: A perturbed angular correlation of gamma-rays spectroscopic study.
pubmed:affiliation
Department of Physics, The Royal Veterinary and Agricultural University, Frederiksberg C, Denmark.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't