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Gas Phase Structure of Sodiated Amino Acids Probed by H/D Exchange Reactions

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Polje Vrijednost
 
Naslov Gas Phase Structure of Sodiated Amino Acids Probed by H/D Exchange Reactions
Određivanje strukture natrijem kationiranih aminokiselina u plinskoj fazi pomoću H/D izmjene
 
Autor Rožman, Marko
 
Tema gas phase structure sodium cationized amino acids sodium cationized amino acid esters mass spectrometry density functional theory zwitterionic structure
 
Opis Taking into account the difference in structure of a sodiated gas phase amino acid in its zwitterionic and charge solvated forms, gas phase structures of sodiated histidine, lysine, phenylalanine, proline, tryptophan and tyrosine were probed by H/D exchange reactions. Experiment results obtained from the site-specific reaction rate constants indicated the zwitterionic structure for all the sodiated amino acids studied. In contrast, B3LYP calculations for sodiated lysine, along with the already presented theoretical results for other amino acids studied, show the charge solvated form to be stable, except for proline which is in the zwitterionic form. Absence of H/D exchange in sodiated methyl esters of phenylalanine and histidine, along with the discrepancy between experimental and theoretical data for the amino acids studied, indicates that H/D exchange occurs only when sodiated amino acids are in the zwitterionic form.
Obzirom na različitu strukturu natrijem kationirane aminokiseline u zwitterionskoj formi od one u formi solvatiranoga naboja, moguće je promatrajući H/D izmjenu razlikovati te dvije strukture. Informacije dobivene određivanjem konstanti brzine kemijske reakcije na specifična mjesta u molekuli ukazuju da se promatrane natrijem kationirane aminokiseline: histidin, lizin, fenilalanin, prolin, triptofan i tirozin nalaze u zwitterionskoj formi. Nasuprot tome, B3LYP rezultati za natrijem kationirani lizin zajedno s već publiciranim rezultatima za ostale promatrane aminokiseline ukazuju da se iste u plinskoj fazi nalaze u formi solvatiranoga naboja, uz iznimku prolina koji se nalazi u zwitterionskoj formi. Izostanak H/D izmjene na natrijem kationiranim metilnim esterima histidina i fenilalanina zajedno s neslaganjem teorijskih i eksperimentalnih rezultata upućuje da u eksperimentima H/D izmjene do iste dolazi samo kada je natrijem kationirana aminokiselina u zwiterionskoj formi. . .
 
Izdavač Croatian Chemical Society
 
Datum 2005-06-15
 
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Format (na primjer PDF) pdf
 
Identifikator http://hrcak.srce.hr/10
http://hrcak.srce.hr/file/10
 
Izvor Croatica Chemica Acta (cca@chem.pmf.hr); Vol.78 No.2; ISSN 0011-1643 (Print); ISSN 1334-417X (Online)
 
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