Linked Life Data

9741844

Source:http://linkedlifedata.com/resource/pubmed/id/9741844

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1999-1-19
pubmed:abstractText
Human placental alkaline phosphatase is a membrane-anchored dimeric protein. Unfolding of the enzyme by guanidinium chloride (GdmCl) caused a decrease of the fluorescence intensity and a large red-shifting of the protein fluorescence maximum wavelength from 332 to 346 nm. The fluorescence changes were completely reversible upon dilution. GdmCl induced a clear biphasic fluorescence spectrum change, suggesting that a three-state unfolding mechanism with an intermediate state was involved in the denaturation process. The half unfolding GdmCl concentrations, [GdmCl]0.5, corresponding to the two phases were 1.45 M and 2.50 M, respectively. NaCl did not cause the same effect as GdmCl, indicating that the GdmCl-induced biphasic denaturation is not a salt effect. The decrease in fluorescence intensity was monophasic, corresponding to the first phase of the denaturation process with [GdmCl]0.5 = 1.37 M and reached a minimum at 1.5 M GdmCl, where the enzyme remained completely active. The enzymatic activity lost started at 2.0 M GdmCl and was monophasic but coincided with the second-phase denaturation with [GdmCl]0.5 = 2.46 M. Inorganic phosphate provides substantial protection of the enzyme against GdmCl inactivation. Determining the molecular weight by sucrose-density gradient ultracentrifugation revealed that the enzyme gradually dissociates in both phases. Complete dissociation occurred at [GdmCl] > 3 M. The dissociated monomers reassociated to dimers after dilution of the GdmCl concentration. Refolding kinetics for the first-phase denaturation is first-order but not second-order. The biphasic phenomenon thereby was a mixed dissociation-denaturation process. A completely folded monomer never existed during the GdmCl denaturation. The biphasic denaturation curve thereby clearly demonstrates an enzymatically fully active intermediate state, which could represent an active-site structure intact and other structure domains partially melted intermediate state.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0887-3585
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
33
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
49-61
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Biphasic denaturation of human placental alkaline phosphatase in guanidinium chloride.
pubmed:affiliation
Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of China.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't