3 research outputs found
Landing Proteins on Graphene Trampoline Preserves Their Gas-Phase Folding on the Surface
Molecule–surface
collisions are known to initiate dynamics
that lead to products inaccessible by thermal chemistry. These collision
dynamics, however, have mostly been examined on bulk surfaces, leaving
vast opportunities unexplored for molecular collisions on nanostructures,
especially on those that exhibit mechanical properties radically different
from those of their bulk counterparts. Probing energy-dependent dynamics
on nanostructures, particularly for large molecules, has been challenging
due to their fast time scales and high structural complexity. Here,
by examining the dynamics of a protein impinging on a freestanding,
single-atom-thick membrane, we discover molecule-on-trampoline dynamics that disperse the collision impact away from the incident
protein within a few picoseconds. As a result, our experiments and ab initio calculations show that cytochrome c retains its
gas-phase folded structure when it collides onto freestanding single-layer
graphene at low energies (∼20 meV/atom). The molecule-on-trampoline dynamics, expected to be operative on many freestanding atomic membranes,
enable reliable means to transfer gas-phase macromolecular structures
onto freestanding surfaces for their single-molecule imaging, complementing
many bioanalytical techniques
Landing Proteins on Graphene Trampoline Preserves Their Gas-Phase Folding on the Surface
Molecule–surface
collisions are known to initiate dynamics
that lead to products inaccessible by thermal chemistry. These collision
dynamics, however, have mostly been examined on bulk surfaces, leaving
vast opportunities unexplored for molecular collisions on nanostructures,
especially on those that exhibit mechanical properties radically different
from those of their bulk counterparts. Probing energy-dependent dynamics
on nanostructures, particularly for large molecules, has been challenging
due to their fast time scales and high structural complexity. Here,
by examining the dynamics of a protein impinging on a freestanding,
single-atom-thick membrane, we discover molecule-on-trampoline dynamics that disperse the collision impact away from the incident
protein within a few picoseconds. As a result, our experiments and ab initio calculations show that cytochrome c retains its
gas-phase folded structure when it collides onto freestanding single-layer
graphene at low energies (∼20 meV/atom). The molecule-on-trampoline dynamics, expected to be operative on many freestanding atomic membranes,
enable reliable means to transfer gas-phase macromolecular structures
onto freestanding surfaces for their single-molecule imaging, complementing
many bioanalytical techniques
On the Influence of Water on the Electronic Structure of Firefly Oxyluciferin Anions from Absorption Spectroscopy of Bare and Monohydrated Ions in Vacuo
A complete
understanding of the physics underlying the varied colors
of firefly bioluminescence remains elusive because it is difficult
to disentangle different enzyme–lumophore interactions. Experiments
on isolated ions are useful to establish a proper reference when there
are no microenvironmental perturbations. Here, we use action spectroscopy
to compare the absorption by the firefly oxyluciferin lumophore isolated
in vacuo and complexed with a single water molecule. While the process
relevant to bioluminescence within the luciferase cavity is light
emission, the absorption data presented here provide a unique insight
into how the electronic states of oxyluciferin are altered by microenvironmental
perturbations. For the bare ion we observe broad absorption with a
maximum at 548 ± 10 nm, and addition of a water molecule is found
to blue-shift the absorption by approximately 50 nm (0.23 eV). Test
calculations at various levels of theory uniformly predict a blue-shift
in absorption caused by a single water molecule, but are only qualitatively
in agreement with experiment highlighting limitations in what can
be expected from methods commonly used in studies on oxyluciferin.
Combined molecular dynamics simulations and time-dependent density
functional theory calculations closely reproduce the broad experimental
peaks and also indicate that the preferred binding site for the water
molecule is the phenolate oxygen of the anion. Predicting the effects
of microenvironmental interactions on the electronic structure of
the oxyluciferin anion with high accuracy is a nontrivial task for
theory, and our experimental results therefore serve as important
benchmarks for future calculations