Enzyme Tunneling Flashcards
(21 cards)
What is tunnelling?
Tunnelling is the phenomenon where a species passes through a physical or energetic barrier.
What is a particle?
Something solid
Obeys classical Newtonian physics
What is a wave?
Something intangible
Obeys quantum mechanics
_ exists as both a particle and a wave, but it is a spectrum
Everything
The only things that meaningfully tunnel are things up to a _
Hydride
What is the de Broglie relation?
λ=h/mv
Large mass means more or less particle like?
More
What is the wavefunction?
It describes the probability of where something might be found.
The greater percentage of the wavefunction on the acceptor side of the barrier, the greater the _
Probability of the transfer.
What is the key determiner in whether an electron will tunnel?
Width of the barrier
What is Marcus theory?
Reorganisation of environment prior to electron transfer.
Electron transfer is not activationless
Replaces TST for redox reactions
What is the reorganisation energy λ
The energy required to ‘reorganise’ the nuclear coordinates to a configuration which allows ET
What is the Frank-Condon principle
The positions and momentum of nuclei varies much more slowly than for electrons.
The rate of ET is maximal when -ΔG° _ λ
=
It is _ which determines the free energy of activation and thus the reaction rate
Solvent polarization
What is gating
Where enzymes kinetically distinguish the back reaction by making it slower and slower.
Barrier compression _ the rate of H-tunnelling
Increases
True or false:
Isotopic substitution will alter the potential energy surface for nuclear motion but will not alter the frequency of nuclear motion
False
Isotopic substitution will not alter the potential energy surface for nuclear motion but will alter the frequency of nuclear motion
Born Oppenheimer enzyme
Increasing the mass of a molecule will not alter the structure of that molecule but it will make it vibrate more slowly
Mass change changes an enzymes susceptibility to _ changes
Temperature
Vectorial electron transfer is driven by enzyme _
Motion
