  Biological order provided by $\alpha$-helical secondary protein structures is
an important resource exploitable by living organisms for increasing the
efficiency of energy transport. In particular, self-trapping of amide I energy
quanta by the induced phonon deformation of the hydrogen-bonded lattice of
peptide groups is capable of generating either pinned or moving solitary waves
following the Davydov quasiparticle/soliton model. The effect of applied
in-phase Gaussian pulses of amide I energy, however, was found to be strongly
dependent on the site of application. Moving solitons were only launched when
the amide I energy was applied at one of the $\alpha$-helix ends, whereas
pinned solitons were produced in the $\alpha$-helix interior. In this paper, we
describe a general mechanism that launches moving solitons in the interior of
the $\alpha$-helix through phase-modulated Gaussian pulses of amide I energy.
We also compare the predicted soliton velocity based on effective soliton mass
and the observed soliton velocity in computer simulations for different
parameter values of the isotropy of the exciton-phonon interaction. The
presented results demonstrate the capacity for explicit control of soliton
velocity in protein $\alpha$-helices, and further support the plausibility of
gradual optimization of quantum dynamics for achieving specialized protein
functions through natural selection.
