Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum Transition State Theory for proton transfer reactions in enzymes   We consider the role of quantum effects in the transfer of hyrogen-like
species in enzyme-catalysed reactions. This study is stimulated by claims that
the observed magnitude and temperature dependence of kinetic isotope effects
imply that quantum tunneling below the energy barrier associated with the
transition state significantly enhances the reaction rate in many enzymes. We
use a path integral approach which provides a general framework to understand
tunneling in a quantum system which interacts with an environment at non-zero
temperature. Here the quantum system is the active site of the enzyme and the
environment is the surrounding protein and water. Tunneling well below the
barrier only occurs for temperatures less than a temperature $T_0$ which is
determined by the curvature of potential energy surface near the top of the
barrier. We argue that for most enzymes this temperature is less than room
temperature. For physically reasonable parameters quantum transition state
theory gives a quantitative description of the temperature dependence and
magnitude of kinetic isotope effects for two classes of enzymes which have been
claimed to exhibit signatures of quantum tunneling. The only quantum effects
are those associated with the transition state, both reflection at the barrier
top and tunneling just below the barrier. We establish that the friction due to
the environment is weak and only slightly modifies the reaction rate.
Furthermore, at room temperature and for typical energy barriers environmental
degrees of freedom with frequencies much less than 1000 cm$^{-1}$ do not have a
significant effect on quantum corrections to the reaction rate.

32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
10
The categories of this paper are: q-bio