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Titolo:
CHIRAL DISCRIMINATION IN THE FORMATION OF DIASTEREOMERIC PAIRS - A THERMODYNAMIC AND CONFORMATIONAL INVESTIGATION
Autore:
PISPISA B; VENANZI M; PALLESCHI A;
Indirizzi:
UNIV ROMA TOR VERGATA,DIPARTIMENTO SCI & TECNOL CHIM I-00133 ROME ITALY UNIV ROMA LA SAPIENZA,DIPARTIMENTO CHIM I-00185 ROME ITALY
Titolo Testata:
Journal of the Chemical Society. Faraday transactions
fascicolo: 3, volume: 90, anno: 1994,
pagine: 435 - 443
SICI:
0956-5000(1994)90:3<435:CDITFO>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
IRON(III) COMPLEX-IONS; STEREOSELECTIVE ELECTRON-TRANSFER; HYDROGEN-BOND INTERACTIONS; OCCURRING AMINO-ACIDS; ASYMMETRIC POLYMERS; NONBONDED INTERACTIONS; ENERGY PARAMETERS; POLYPEPTIDES; OXIDATION; BINDING;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
38
Recensione:
Indirizzi per estratti:
Citazione:
B. Pispisa et al., "CHIRAL DISCRIMINATION IN THE FORMATION OF DIASTEREOMERIC PAIRS - A THERMODYNAMIC AND CONFORMATIONAL INVESTIGATION", Journal of the Chemical Society. Faraday transactions, 90(3), 1994, pp. 435-443

Abstract

Chiral discrimination in the formation of diastereomeric adducts between L-(+)-ascorbic acid and enantiomeric alpha-helical polypeptides carrying Fe-III complex ions has been investigated by microcalorimetric measurements (25 degrees C) as well as by theoretical conformational analysis. Stereoselectivity in the binding results from a complex interplay of ionic and non-bonded interactions that ultimately leads to modest effects, in full agreement with experimental data. These results are consistent with those obtained earlier by using L-dopa (L-dihydroxyphenylalanine) and L-adrenaline as substrates. The diastereomeric complexes were also found to undergo an intramolecular electron transfer from the substrate to the central metal ion with a kinetic stereoselectivity definitely higher than the thermodynamic one. Both these effectsand the lack of stereoselectivity in the formation of the associationcomplexes with L-cysteine are discussed in the light of the relationship between chiral discrimination and modes of binding of asymmetric species. A statistical analysis is reported, suggesting that efficiencyin chiral recognition and discrimination demands sterically constrained species in that conformational rigidity enhances steric differencesbetween the diastereomeric pairs.

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Documento generato il 22/09/20 alle ore 03:09:07