Complexing of riboflavin with the enolate form of barbituric acid

Malka Gorodetsky; Ruth F. Weiner; Wilhelm R. Frisell

doi:10.1016/0005-2728(72)90086-2

Complexing of riboflavin with the enolate form of barbituric acid

Malka Gorodetsky, Ruth F. Weiner, Wilhelm R. Frisell

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

Riboflavin and the enolate form of barbituric acid form a complex at pH 7.80 as demonstrated by the appearance of two new absorption bands at 400 and 490 nm. The association constant for the complex determined from a Benesi-Hildebrand analysis of absorbances at 490 nm is 30 M^-1. The K evaluated from fluorescence quenching at various barbiturate: riboflavin ratios is 33 M^-1. The complexing of the barbiturate and riboflavin is accompanied by an inhibition of the photo-oxidation of sarcosine to formaldehyde. Under the same conditions, the barbiturate enhances the rate of photo-oxidation of NADH. The 5,5-disubstituted barbiturates do not give a new absorption band with riboflavin and do not inhibit the photo-oxidation of sarcosine, indicating that an enolate configuration of the β-diketone system is involved in complexing with riboflavin.

Original language	English
Pages (from-to)	582-585
Number of pages	4
Journal	Biochimica et Biophysica Acta - Bioenergetics
Volume	256
Issue number	2
DOIs	https://doi.org/10.1016/0005-2728(72)90086-2
State	Published - 28 Feb 1972
Externally published	Yes

ASJC Scopus subject areas

Biophysics
Biochemistry
Cell Biology

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title = "Complexing of riboflavin with the enolate form of barbituric acid",

abstract = "Riboflavin and the enolate form of barbituric acid form a complex at pH 7.80 as demonstrated by the appearance of two new absorption bands at 400 and 490 nm. The association constant for the complex determined from a Benesi-Hildebrand analysis of absorbances at 490 nm is 30 M-1. The K evaluated from fluorescence quenching at various barbiturate: riboflavin ratios is 33 M-1. The complexing of the barbiturate and riboflavin is accompanied by an inhibition of the photo-oxidation of sarcosine to formaldehyde. Under the same conditions, the barbiturate enhances the rate of photo-oxidation of NADH. The 5,5-disubstituted barbiturates do not give a new absorption band with riboflavin and do not inhibit the photo-oxidation of sarcosine, indicating that an enolate configuration of the β-diketone system is involved in complexing with riboflavin.",

author = "Malka Gorodetsky and Weiner, {Ruth F.} and Frisell, {Wilhelm R.}",

note = "Funding Information: This work was supported in part by a Grant from the U.S. Public Health Service (AM-oo969-I6).",

year = "1972",

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day = "28",

doi = "10.1016/0005-2728(72)90086-2",

language = "English",

volume = "256",

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journal = "Biochimica et Biophysica Acta - Bioenergetics",

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T1 - Complexing of riboflavin with the enolate form of barbituric acid

AU - Gorodetsky, Malka

AU - Weiner, Ruth F.

AU - Frisell, Wilhelm R.

N1 - Funding Information: This work was supported in part by a Grant from the U.S. Public Health Service (AM-oo969-I6).

PY - 1972/2/28

Y1 - 1972/2/28

N2 - Riboflavin and the enolate form of barbituric acid form a complex at pH 7.80 as demonstrated by the appearance of two new absorption bands at 400 and 490 nm. The association constant for the complex determined from a Benesi-Hildebrand analysis of absorbances at 490 nm is 30 M-1. The K evaluated from fluorescence quenching at various barbiturate: riboflavin ratios is 33 M-1. The complexing of the barbiturate and riboflavin is accompanied by an inhibition of the photo-oxidation of sarcosine to formaldehyde. Under the same conditions, the barbiturate enhances the rate of photo-oxidation of NADH. The 5,5-disubstituted barbiturates do not give a new absorption band with riboflavin and do not inhibit the photo-oxidation of sarcosine, indicating that an enolate configuration of the β-diketone system is involved in complexing with riboflavin.

AB - Riboflavin and the enolate form of barbituric acid form a complex at pH 7.80 as demonstrated by the appearance of two new absorption bands at 400 and 490 nm. The association constant for the complex determined from a Benesi-Hildebrand analysis of absorbances at 490 nm is 30 M-1. The K evaluated from fluorescence quenching at various barbiturate: riboflavin ratios is 33 M-1. The complexing of the barbiturate and riboflavin is accompanied by an inhibition of the photo-oxidation of sarcosine to formaldehyde. Under the same conditions, the barbiturate enhances the rate of photo-oxidation of NADH. The 5,5-disubstituted barbiturates do not give a new absorption band with riboflavin and do not inhibit the photo-oxidation of sarcosine, indicating that an enolate configuration of the β-diketone system is involved in complexing with riboflavin.

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DO - 10.1016/0005-2728(72)90086-2

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JF - Biochimica et Biophysica Acta - Bioenergetics

IS - 2

ER -

Complexing of riboflavin with the enolate form of barbituric acid

Abstract

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