54 research outputs found
Towards Quantitative Classification of Folded Proteins in Terms of Elementary Functions
A comparative classification scheme provides a good basis for several
approaches to understand proteins, including prediction of relations between
their structure and biological function. But it remains a challenge to combine
a classification scheme that describes a protein starting from its well
organized secondary structures and often involves direct human involvement,
with an atomary level Physics based approach where a protein is fundamentally
nothing more than an ensemble of mutually interacting carbon, hydrogen, oxygen
and nitrogen atoms. In order to bridge these two complementary approaches to
proteins, conceptually novel tools need to be introduced. Here we explain how
the geometrical shape of entire folded proteins can be described analytically
in terms of a single explicit elementary function that is familiar from
nonlinear physical systems where it is known as the kink-soliton. Our approach
enables the conversion of hierarchical structural information into a
quantitative form that allows for a folded protein to be characterized in terms
of a small number of global parameters that are in principle computable from
atomary level considerations. As an example we describe in detail how the
native fold of the myoglobin 1M6C emerges from a combination of kink-solitons
with a very high atomary level accuracy. We also verify that our approach
describes longer loops and loops connecting -helices with
-strands, with same overall accuracy.Comment: 3 figure
Research on the transition dynamics and linear (nonlinear) optical properties of mCherry
In this study, we explore the electron transition mechanism and optical
properties of the popular red fluorescent protein mCherry. By examining the
charge transfer spectrum and combining it with the mCherry hole-electron
distribution, we identify that the charge transfer between the phenolate and
imidazolinone loops significantly contributes to the absorption spectrum.
Quantitative analysis of charge transfer shows that, overall, the electrons are
transferred to the C16 atom in the middle of phenolate and the imidazolinone
loops during absorption. We speculate that C16 may also absorb protons to
enable the photoconversion of mCherry in the excited state, similar to the
blinking mechanism of IrisFP. In addition, we further investigated the optical
properties of mcherry in the external field by polarizability
(hyperpolarizability), showing the anisotropy of the polarization, the first
hyperpolarization and the second hyperpolarization by unit spherical
representation. Our results suggest that significant polarization and second
hyperpolarizability occur when the field direction and electron transfer
direction are aligned. We also analyzed the polarizability and first
hyperpolarizabilities for different external fields. The polarizability mutated
when the external field satisfies the S_0,min-> S_1 transition. Finally, the
study of the first hyperpolarizability shows that adjusting the appropriate
field can lead to a linear photoelectric effect or second harmonic generation
of mCherry. These studies have certain reference values for various red
fluorescent protein correlation simulations and experiments because of the
similarity of the red fluorescent protein
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