Linked Life Data

7730353

Source:http://linkedlifedata.com/resource/pubmed/id/7730353

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
17
pubmed:dateCreated
1995-6-1
pubmed:abstractText
Crystallographic analysis indicated that Clostridium thermocellum endoglucanase CelD contained three Ca(2+)-binding sites, termed A, B, and C, and one Zn(2+)-binding site. The protein contributed five, six, and three of the coordinating oxygen atoms present at sites A, B, and C, respectively. Proteins altered by mutation in site A (CelDD246A), B (CelDD361A), or C (CelDD523A) were compared with wild type CelD. The Ca(2+)-binding isotherm of wild type CelD was compatible with two high affinity sites (Ka = 2 x 10(6) M-1) and one low affinity site (Ka < 10(5) M-1). The Ca(2+)-binding isotherms of the mutated proteins showed that sites A and B were the two high affinity sites and that site C was the low affinity site. Atomic absorption spectrometry confirmed the presence of one tightly bound Zn2+ atom per CelD molecule. The inactivation rate of CelD at 75 degrees C was decreased 1.9-fold upon increasing the Ca2+ concentration from 2 x 10(-5) to 10(-3) M. The Km of CelD was decreased 1.8-fold upon increasing the Ca2+ concentration from 5 x 10(-6) to 10(-4) M. Over similar ranges of concentration, Ca2+ did not affect the thermostability nor the kinetic properties of CelDD523A. These findings suggest that Ca2+ binding to site C stabilizes the active conformation of CelD in agreement with the close vicinity of site C to the catalytic center.
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
28
pubmed:volume
270
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
9757-62
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Structural and functional analysis of the metal-binding sites of Clostridium thermocellum endoglucanase CelD.
pubmed:affiliation
URA 1300 CNRS, Département des Biotechnologies, Institut Pasteur, Paris, France.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't