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Vibrational modes of flavin bound to riboflavin binding protein from egg white. Resonance Raman spectra of lumiflavin and 8-substituted riboflavin.
J Biochem ; 88(2): 403-9, 1980 Aug.
Article em En | MEDLINE | ID: mdl-7419501
The resonance Raman (RR) spectra of 8-halogenated-riboflavin, 8-demethyl-riboflavin(8-H-RF), 8-amino-riboflavin(8-NH2-RF), 8-methoxy-riboflavin(8-OCH3-RF), lumiflavin, and 3-methyl-lumiflavin were observed. The Raman lines with the highest frequency are at 1624, 1620, and 1615 cm-1 for 8-chloro-riboflavin, 8-bromo-riboflavin, and 8-iodo-riboflavin, respectively. This systematic shift confirms that the 1631 cm-1 line of riboflavin is derived from the benzene part of isoalloxazine. Substitution at the 8-position by an amino or methoxy group, which has a large influence on the electronic structure of isoalloxazine, changes the RR spectrum markedly in comparison with that of 8-halogenated riboflavin. The 1583 cm-1 line of riboflavin, which involves the vibrational displacement of N(5) and C(4a) atoms of isoalloxazine, is shifted to the low frequency side by substitution at the 8-position with an amino or methoxy group. The corresponding line of 8-H-RF, on the contrary, shifts to the high frequency side. The RR spectrum of lumiflavin is very different from that of riboflavin in the range from 1200 to 1300 cm-1. Although the pi-electronic structure is little affected by the substitution at the 10-position, the Raman spectrum of lumiflavin in this region is very sensitive.
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Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Proteínas de Membrana Transportadoras / Riboflavina / Proteínas de Transporte / Flavinas Idioma: En Ano de publicação: 1980 Tipo de documento: Article
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Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Proteínas de Membrana Transportadoras / Riboflavina / Proteínas de Transporte / Flavinas Idioma: En Ano de publicação: 1980 Tipo de documento: Article