Abstract.
The reaction mechanism of flavin-catalyzed dehydrogenation of glycine has been studied by ab initio molecular orbital calculations using the 6-31G* basis set. 10-Methyl isoalloxazine (10-MIA) has been used as the flavin model compound. The results showed that when we assume a proton transport channel in amino acid oxidase, which is switched on by the substrate anion, the O12-protonated 10-MIA [10-MIAH+(O12)] is generated. The main structure of 10-MIAH+(O12) is one in which the central ring is expressed by an NAD+-like structure, which is favorable for driving the hydride-transfer reaction, i.e., the abstraction of the α-hydrogen of glycine by the hydride-transfer mechanism. We have found that this protonation results in a dramatic lowering of the activation energy of the reaction. The proposed mechanism is summarized as follows: the hydride transfer proceeds via two-electron transfer and synchronous intramolecular proton transfer → intermolecular proton transfer.
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Received: 10 August 1998 / Accepted: 17 September 1998 / Published online: 8 February 1999
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Nishimoto, K., Higashimura, K. & Asada, T. Ab initio molecular orbital study of the flavin-catalyzed dehydrogenation reaction of glycine - protein transport channel driving hydride-transfer mechanism. Theor Chem Acc 102, 355–365 (1999). https://doi.org/10.1007/s002140050507
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DOI: https://doi.org/10.1007/s002140050507