Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Kinetically Trapped Liquid-State Conformers of a Sodiated Model Peptide
  Observed in the Gas Phase   We investigate the peptide AcPheAla5LysH+, a model system for studying helix
formation in the gas phase, in order to fully understand the forces that
stabilize the helical structure. In particular, we address the question of
whether the local fixation of the positive charge at the peptide's C-terminus
is a prerequisite for forming helices by replacing the protonated C-terminal
Lys residue by Ala and a sodium cation. The combination of gas-phase
vibrational spectroscopy of cryogenically cooled ions with molecular
simulations based on density-functional theory (DFT) allows for detailed
structure elucidation. For sodiated AcPheAla6, we find globular rather than
helical structures, as the mobile positive charge strongly interacts with the
peptide backbone and disrupts secondary structure formation. Interestingly, the
global minimum structure from simulation is not present in the experiment. We
interpret that this is due to high barriers involved in re-arranging the
peptide-cation interaction that ultimately result in kinetically trapped
structures being observed in the experiment.

11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
9
The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
30
The categories of this paper are: q-alg