Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Parallel versus off-pathway Michaelis-Menten mechanism for single-enzyme
  kinetics of a fluctuating enzyme   Recent fluorescence spectroscopy measurements of the turnover time
distribution of single-enzyme turnover kinetics of $\beta$-galactosidase
provide evidence of Michaelis-Menten kinetics at low substrate concentration.
However, at high substrate concentrations, the dimensionless variance of the
turnover time distribution shows systematic deviations from the
Michaelis-Menten prediction. This difference is attributed to conformational
fluctuations in both the enzyme and the enzyme-substrate complex and to the
possibility of both parallel and off-pathway kinetics. Here, we use the
chemical master equation to model the kinetics of a single fluctuating enzyme
that can yield a product through either parallel or off-pathway mechanisms. An
exact expression is obtained for the turnover time distribution from which the
mean turnover time and randomness parameters are calculated. The parallel and
off-pathway mechanisms yield strikingly different dependences of the mean
turnover time and the randomness parameter on the substrate concentration. In
the parallel mechanism, the distinct contributions of enzyme and
enzyme-substrate fluctuations are clearly discerned from the variation of the
randomness parameter with substrate concentration. From these general results
we conclude that an off-pathway mechanism, with substantial enzyme-substrate
fluctuations, is needed to rationalize the experimental findings of
single-enzyme turnover kinetics of $\beta$-galactosidase.

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The categories of this paper are: atom-ph
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The categories of this paper are: adap-org
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: bayes-an
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The categories of this paper are: supr-con
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The categories of this paper are: astro-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ph
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The categories of this paper are: q-fin
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-bio
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The categories of this paper are: eess
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The categories of this paper are: quant-ph