Systematic theoretical investigation on the light emitter of firefly

• This is a systematic theoretical investigation on all the possible light emitters of firefly using multireference method. Six chemical forms of oxyluciferin (OxyLH2) molecules/anions were studied by a multi-state complete active space second order perturbation (MS-CASPT2) method in vacuum and DMSO. The calculated results and subsequent analysis excluded enol-OxyLH2, keto-OxyLH2 and enolate-OxyLH- as possible light emitters. The remaining three candidates, phenolate-enol-OxyLH-, phenolate-keto-OxyLH- and OxyL2-, were further investigated in protein by a MS-CASPT2/molecular mechanics (MM) study to explain the natural bioluminescence of firefly. By comparison of the MS-CASPT2/MM calculated results of phenolate-enol-OxyLH-, phenolate-keto-OxyLH- and OxyL2- with the experimental observation and detailed analysis, we concluded that the direct decomposition excited-state product of firefly dioxetanone in vivo and the only light emitter of firefly in natural bioluminescence is the first singlet exited state (S1) of phenolate-keto-OxyLH-.

Ämnesord

NATURVETENSKAP  -- Kemi -- Teoretisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Theoretical Chemistry (hsv//eng)

Nyckelord

Quantum chemistry

Kvantkemi

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