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Geometric phaselike effects in a quantum heat engine
By periodically driving the temperatures of reservoirs in quantum heat
engines, geometric phase or Pancharatnam-Berry phase-like (PBp) effects in the
thermodynamics can be observed. The PBp can be identified from a generating
function (GF) method within an adiabatic quantum Markovian master equation
formalism. The GF is shown not to lead to a standard open quantum system's
fluctuation theorem in presence of phase-different modulations with an
inapplicability in the use of the popular large deviation theory. Effect of
coherences on the optimized value of the flux is nullified due to PBp
contributions. The PBp causes the universality of the linear coefficient in the
expansion of the efficiency at maximum power in terms of Carnot efficiency to
be violated.Comment: 8 pages, 4 figure
Toward an Alternative Intrinsic Probe for Spectroscopic Characterization of a Protein
The intrinsic fluorescent amino acid tryptophan is the unanimous choice for the spectroscopic investigation
of proteins. However, several complicacies in the interpretation of tryptophan fluorescence in a protein are
inevitable and an alternative intrinsic protein probe is a longstanding demand. In this contribution, we report
an electron-transfer reaction in a human transporter protein (HSA) cavity which causes the tryptophan residue
(Trp214) to undergo chemical modification to form one of its metabolites kynurenine (Kyn214). Structural
integrity upon modification of the native protein is confirmed by dynamic light scattering (DLS) as well as
near and far circular dichroism (CD) spectroscopy. Femtosecond-resolved fluorescence transients of the modified
protein describe the dynamics of solvent molecules in the protein cavity in both the native and denatured
states. In order to establish general use of the probe, we have studied the dipolar interaction of Kyn214 with
a surface-bound ligand (crystal violet, CV) of the protein. By using the sensitivity of FRET, we have determined
the distance between Kyn214 (donor) and CV (acceptor). Our study is an attempt to explore an alternative
intrinsic fluorescence probe for the spectroscopic investigation of a protein. In order to establish the efficacy
of the modification technique we have converted the tryptophan residues of other proteins (bovine serum
albumin, chymotrypsin and subtilisin Carlsberg) to kynurenine and confirmed their structural integrity. We
have also shown that catalytic activity of the enzymes remains intact upon the modification
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