Linked Life Data

11054655

Source:http://linkedlifedata.com/resource/pubmed/id/11054655

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
2000-12-11
pubmed:abstractText
The zinc(II)-L-carnosine system was investigated at different pH and metal/ligand ratios by Raman and IR spectroscopy. The Raman and IR spectra present some marker bands useful to identify the sites involved in metal chelation at a specific pH value. In particular, the neutral imidazole group gives rise to some Raman bands, such as the nu C(4)===C(5) band, that change in wave number, depending on whether the imidazole ring takes the tautomeric form I or II. Even if tautomer I is predominant in the free ligand, metal coordination can upset tautomeric preference and N(tau)- and N(pi)-ligated complexes can be identified. Although weak compared to those of aromatic residues, these Raman marker bands may be useful in analyzing metal-histidine interaction in peptides and proteins. On the basis of the vibrational results, conclusions can be drawn on the species existing in the system. Depending on the available nitrogen atoms, various complexes can be formed and the prevalent form of the species depends mainly on the pH. At basic pH carnosine gives rise to two different neutral complexes: a water-insoluble polymeric species, [ZnH(-1)L](0)(n), and a dimer, [Zn(2)H(-2)L(2)](0). The first is predominant and involves the tautomeric I form of the imidazole ring in metal chelation; the second contains tautomer II and increases its percentage by going from a 2 to 0.25 metal/ligand ratio. Conversely, the dimeric species dominates at pH 7, whereas two charged species, [ZnHL](2+) and [ZnL](+), are formed under slightly acidic conditions. In the [ZnHL](2+) complex the imidazole ring takes part in the Zn(II) coordination in the tautomeric I form, whereas in [ZnL](+) the ring is protonated and not bound to the Zn(II) ion. In addition, the curve fitting analysis of the 1700-1530 cm(-1) Raman region was helpful in indicating the predominant species at each pH.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
0006-3525
pubmed:author
pubmed:copyrightInfo
Copyright 2000 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 57: 352-364, 2000
pubmed:issnType
Print
pubmed:volume
57
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
352-64
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Raman and IR spectroscopic investigation of zinc(II)-carnosine complexes.
pubmed:affiliation
Centro di Studio Interfacoltà sulla Spettroscopia Raman, Department of Biochemistry, University of Bologna, via Belmeloro 8/2, 40126 Bologna, Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't