Linked Life Data

11401577

Source:http://linkedlifedata.com/resource/pubmed/id/11401577

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
24
pubmed:dateCreated
2001-6-12
pubmed:abstractText
Allium sativum agglutinin (ASAI) is a heterodimeric mannose-specific bulb lectin possessing two polypeptide chains of molecular mass 11.5 and 12.5 kDa. The thermal unfolding of ASAI, characterized by differential scanning calorimetry and circular dichroism, shows it to be highly reversible and can be defined as a two-state process in which the folded dimer is converted directly to the unfolded monomers (A2 if 2U). Its conformational stability has been determined as a function of temperature, GdnCl concentration, and pH using a combination of thermal and isothermal GdnCl-induced unfolding monitored by DSC, far-UV CD, and fluorescence, respectively. Analyses of these data yielded the heat capacity change upon unfolding (DeltaC(p) and also the temperature dependence of the thermodynamic parameters, namely, DeltaG, DeltaH, and DeltaS. The fit of the stability curve to the modified Gibbs-Helmholtz equation provides an estimate of the thermodynamic parameters DeltaH(g), DeltaS(g), and DeltaC(p) as 174.1 kcal x mol(-1), 0.512 kcal x mol(-1) x K(-1), and 3.41 kcal x mol(-1) x K(-1), respectively, at T(g) = 339.4 K. Also, the free energy of unfolding, DeltaG(s), at its temperature of maximum stability (T(s) = 293 K) is 13.13 kcal x mol(-1). Unlike most oligomeric proteins studied so far, the lectin shows excellent agreement between the experimentally determined DeltaC(p) (3.2 +/- 0.28 kcal x mol(-1) x K(-1)) and those evaluated from a calculation of its accessible surface area. This in turn suggests that the protein attains a completely unfolded state irrespective of the method of denaturation. The absence of any folding intermediates suggests the quaternary interactions to be the major contributor to the conformational stability of the protein, which correlates well with its X-ray structure. The small DeltaC(p) for the unfolding of ASAI reflects a relatively small, buried hydrophobic core in the folded dimeric protein.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
19
pubmed:volume
40
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
7291-300
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:11401577-Agglutinins, pubmed-meshheading:11401577-Calorimetry, pubmed-meshheading:11401577-Carrier Proteins, pubmed-meshheading:11401577-Circular Dichroism, pubmed-meshheading:11401577-Collectins, pubmed-meshheading:11401577-Cotyledon, pubmed-meshheading:11401577-Dimerization, pubmed-meshheading:11401577-Garlic, pubmed-meshheading:11401577-Lectins, pubmed-meshheading:11401577-Mannans, pubmed-meshheading:11401577-Mannose-Binding Lectins, pubmed-meshheading:11401577-Models, Chemical, pubmed-meshheading:11401577-Plant Lectins, pubmed-meshheading:11401577-Plant Proteins, pubmed-meshheading:11401577-Plant Roots, pubmed-meshheading:11401577-Plants, Medicinal, pubmed-meshheading:11401577-Protein Denaturation, pubmed-meshheading:11401577-Protein Folding, pubmed-meshheading:11401577-Protein Structure, Secondary, pubmed-meshheading:11401577-Spectrometry, Fluorescence, pubmed-meshheading:11401577-Thermodynamics
pubmed:year
2001
pubmed:articleTitle
The reversible two-state unfolding of a monocot mannose-binding lectin from garlic bulbs reveals the dominant role of the dimeric interface in its stabilization.
pubmed:affiliation
Molecular Biophysics Unit, Indian Institute of Science, Bangalore-560012, India. kiran@mbu.iisc.ernet.in
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't