Fluoresence quenching of riboflavin in aqueous solution by methionin and cystein |
| |
Institution: | 1. Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering, University of Alcalá, Ctra. Madrid-Barcelona, Km. 33.6, 28871 Alcalá de Henares, Madrid, Spain;2. Institute of Chemistry Research “Andrés M. del Río” (IQAR), University of Alcalá, Ctra, Madrid-Barcelona, Km. 33.6, Alcalá de Henares 28871, Madrid, Spain |
| |
Abstract: | The fluorescence quantum distributions, fluorescence quantum yields, and fluorescence lifetimes of riboflavin in methanol, DMSO, water, and aqueous solutions of the sulphur atom containing amino acids methionin and cystein have been determined. In methanol, DMSO, and water (pH=4–8) only dynamic fluorescence reduction due to intersystem crossing and internal conversion is observed. In aqueous methionin solutions of pH=5.25–9 a pH independent static and dynamic fluorescence quenching occurs probably due to riboflavin anion–methionin cation pair formation. In aqueous cystein solutions (pH range from 4.15 to 9) the fluorescence quenching increases with rising pH due to cystein thiolate formation. The cystein thiol form present at low pH does not react with neutral riboflavin. Cystein thiolate present at high pH seems to react with neutral riboflavin causing riboflavin deprotonation (anion formation) by cystein thiolate reduction to the cystein thiol form. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|