Transition-State Vibrational Analysis and Isotope Effects for COMT-Catalyzed Methyl Transfer.

ABSTRACT: Isotopic partition-function ratios (IPFRs) computed for transition structures (TSs) of the methyl-transfer reaction catalyzed by catechol O-methyltransferase and modeled by hybrid QM/MM methods are analyzed. The ability of smaller Hessians to reproduce trends in α-³H₃ and ¹⁴C_α IPFRs as obtained using the much larger subset QM/MM Hessians from which they are extracted is investigated critically. A 6-atom-extracted Hessian reproduces perfectly the α-T₃ IPFR values from the full-subset Hessians of all the TSs but not the α-¹⁴CIPFRs. Average AM1/OPLS-AA harmonic frequencies and mean-square amplitudes are presented for the 12 normal modes of the α-CH₃ moiety within the active site of several enzymic transition s

SUBMITTER: Roca M 

PROVIDER: S-EPMC7498148 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature