Linked Life Data

8281934

Source:http://linkedlifedata.com/resource/pubmed/id/8281934

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1994-2-14
pubmed:databankReference
pubmed:abstractText
The blood of the teleost Chelodonichthys kumu, living in the temperate waters of New Zealand, contains a single hemoglobin. The complete amino acid sequence of the alpha and beta chain has been established. The presence of a reactive Cys in the external position beta CD8(49) causes polymerisation through intermolecular disulfide bridges between beta chains, with no alteration of functional features. C. kumu Root-effect hemoglobin displays very low or no subunit co-operativity in the physiological pH range. Kinetic experiments on the oxygen dissociation and binding of carbon monoxide show a marked, pH-dependent functional heterogeneity of the two chains, which contributes to the observed reduction of co-operativity. In contrast, kinetic heterogeneity was not observed in the process of CO dissociation, indicating that functional differences between the subunits are detectable only for the dynamic ligand association pathway. The allosteric effector, ATP, seems to increase the pKa of the proton-linked effect on the slow-reacting subunit, affecting the quaternary equilibrium through stabilisation of the T state at lower pH, rather than enhancing the functional heterogeneity itself. In position E11 of both chains, Val (usually present at the distal side of the heme), is substituted by Ile. Although this residue has been shown not to significantly alter ligand binding to the alpha chain, to some extent it can perturb the access of oxygen to the beta chain. Thus, this substitution may be the main reason for subunit functional heterogeneity.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
218
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
829-35
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
A polymerising Root-effect fish hemoglobin with high subunit heterogeneity. Correlation with primary structure.
pubmed:affiliation
Institute of Protein Biochemistry and Enzymology, Consiglio Nazionale delle Ricerche, Naples, Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't