Hydrolysis and rearrangement reactions of riboflavin phosphates. An explicit kinetic study.
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Hydrolysis and rearrangement reactions of riboflavin phosphates. An explicit kinetic study. / Nielsen, Peter; Harksen, J; Bacher, A.
in: EUR J BIOCHEM, Jahrgang 152, Nr. 2, 2, 1985, S. 465-473.Publikationen: SCORING: Beitrag in Fachzeitschrift/Zeitung › SCORING: Zeitschriftenaufsatz › Forschung › Begutachtung
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TY - JOUR
T1 - Hydrolysis and rearrangement reactions of riboflavin phosphates. An explicit kinetic study.
AU - Nielsen, Peter
AU - Harksen, J
AU - Bacher, A
PY - 1985
Y1 - 1985
N2 - Four isomeric monophosphates and five isomeric bisphosphates of riboflavin were isolated from commercial FMN or were prepared by acid-catalyzed isomerization. The reaction of riboflavin monophosphates in aqueous solution was studied in the pH range between 0 and 9 under various conditions. The predominant reaction at pH values below 2 is the acid-catalyzed migration of the phosphate group. A detailed kinetic study of this reaction was performed by high pressure liquid chromatography. Experimental data were fitted with computer-generated curves based on an algorithm for a network of first-order reactions. Rate constants and activation parameters were obtained for the temperature range of 50-80 degrees C at pH 1. At thermodynamic equilibrium, the reaction mixture contains about 66% 5'-phosphate, 11% 4'-phosphate, 8% 3'-phosphate, and 15% 2'-phosphate (pH 1.0, 50 degrees C). In the pH range between 3 and 7, the hydrolysis of FMN is the prevailing reaction with a rate maximum at about pH 4. The same experimental approach was used in a subsequent kinetic study on the isomerization of riboflavin bisphosphates. The formation of five out of six possible isomers was studied quantitatively and rate constants for each partial reaction were obtained.
AB - Four isomeric monophosphates and five isomeric bisphosphates of riboflavin were isolated from commercial FMN or were prepared by acid-catalyzed isomerization. The reaction of riboflavin monophosphates in aqueous solution was studied in the pH range between 0 and 9 under various conditions. The predominant reaction at pH values below 2 is the acid-catalyzed migration of the phosphate group. A detailed kinetic study of this reaction was performed by high pressure liquid chromatography. Experimental data were fitted with computer-generated curves based on an algorithm for a network of first-order reactions. Rate constants and activation parameters were obtained for the temperature range of 50-80 degrees C at pH 1. At thermodynamic equilibrium, the reaction mixture contains about 66% 5'-phosphate, 11% 4'-phosphate, 8% 3'-phosphate, and 15% 2'-phosphate (pH 1.0, 50 degrees C). In the pH range between 3 and 7, the hydrolysis of FMN is the prevailing reaction with a rate maximum at about pH 4. The same experimental approach was used in a subsequent kinetic study on the isomerization of riboflavin bisphosphates. The formation of five out of six possible isomers was studied quantitatively and rate constants for each partial reaction were obtained.
M3 - SCORING: Zeitschriftenaufsatz
VL - 152
SP - 465
EP - 473
IS - 2
M1 - 2
ER -