title: Measurement of the electronic properties of the flavoprotein old yellow enzyme (OYE) and the OYE:p-Cl phenol charge-transfer complex using Stark spectroscopy.
abstract: Low-temperature absorption and Stark spectroscopy have been used to study the electronic properties of oxidized flavin mononucleotide (FMN) in old yellow enzyme (OYE) and OYE complexed with p-chlorophenol (p-Cl phenol). The low-temperature absorbance spectrum of OYE showed splittings of the blue and near-UV vibronic bands, which appears to be due to hydrogen bonding between the isoalloxazine moiety and the protein. A Stark spectroscopic analysis showed that the electronic structure of the FMN cofactor in OYE is not significantly perturbed relative to flavins in simple solvents. However, the charge-transfer band in the OYE:p-Cl phenol complex showed a large Stark effect indicative of substantial charge displacement. The magnitude and direction of this charge displacement are consistent with significant charge transfer along the charge-transfer transition dipole moment direction. In addition, the Stark spectrum of the CT band showed unexpected fine structure that could correlate with vibrational progressions in either the p-Cl phenol donor or the flavin acceptor.
authors.affiliation: Department of Chemistry, Rutgers University, 315 Penn Street, Camden, New Jersey 08102, USA.
authors.forename: Nancy
authors.initials: N
authors.lastname: Hopkins
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Stanley
mesh_terms: D002733:Chlorophenols / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods; D004579:Electron Transport; D004735:Energy Transfer; D005486:Flavin Mononucleotide / Q000737:chemistry; D005415:Flavins / Q000737:chemistry; D005420:Flavoproteins / Q000737:chemistry*; D005615:Freezing; D046911:Macromolecular Substances; D008956:Models, Chemical; D009252:NADPH Dehydrogenase / Q000737:chemistry*; D010084:Oxidation-Reduction; D013056:Spectrophotometry, Ultraviolet; D013057:Spectrum Analysis / Q000379:methods; D055672:Static Electricity
chemical_list: D002733:Chlorophenols; D005415:Flavins; D005420:Flavoproteins; D046911:Macromolecular Substances; C029107:4-chlorophenol; C008173:isoalloxazine; D005486:Flavin Mononucleotide; D009252:NADPH Dehydrogenase