The EZ isomer of BE/HSA is shown to contribute to the ZZ →← ZE photoisomerization of BR/HSA through the excitation of a twisted-state intermediate. Although this isomer is present at extremely low concentration in the photoproducts of BR when bound to HSA, it represents a high quantum yield relaxation channel, competing with the ZZ-ZE isomerization, for the decay of excited BR/HSA to its ground state. Quantitative agreement between theoretical and experimental values of the photoequilibrium rise-times of ZZ →← ZE isomerization of BR/HSA is now obtained. Our results give further support to the recent hypothesis that the EZ isomer is an intermediate in the formation of the cyclized structural isomer of BR/HSA (lumirubin).
The role of E,Z-isomerization in the photochemistry of bilirubin bound to human-serum albumin 'in vitro' / Fusi F.; Agati G.; Pratesi R. - In: LETTERE AL NUOVO CIMENTO DELLA SOCIETÀ ITALIANA DI FISICA. - ISSN 0375-930X. - STAMPA. - 44:(1985), pp. 477-481. [10.1007/BF02746744]
The role of E,Z-isomerization in the photochemistry of bilirubin bound to human-serum albumin 'in vitro'
FUSI, FRANCO;PRATESI, RICCARDO
1985
Abstract
The EZ isomer of BE/HSA is shown to contribute to the ZZ →← ZE photoisomerization of BR/HSA through the excitation of a twisted-state intermediate. Although this isomer is present at extremely low concentration in the photoproducts of BR when bound to HSA, it represents a high quantum yield relaxation channel, competing with the ZZ-ZE isomerization, for the decay of excited BR/HSA to its ground state. Quantitative agreement between theoretical and experimental values of the photoequilibrium rise-times of ZZ →← ZE isomerization of BR/HSA is now obtained. Our results give further support to the recent hypothesis that the EZ isomer is an intermediate in the formation of the cyclized structural isomer of BR/HSA (lumirubin).
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