Biology Reference
In-Depth Information
4.6 The Quantum Information and Enzymic Catalysis
The term “bit” (from binary digit) is defined as the unit of “classical information”
(
C-information
) which must be either 0 or 1. One bit of information allows a binary
choice/decision to be made. The unit of
quantum information
(
Q-information
)is
called “quibit” or “qbit” (from quantum binary digit). Unlike “bit”, “qubit” can be
0, 1 or a superposition of both (i.e., both simultaneously). A qubit assumes the value
of 0 or 1 only after being measured. In other words, a particle carrying Q-informa-
tion can be in both 0 and 1states simultaneously and chooses to be in the 0 or the 1
state only when measured or observed.
An enzyme may be considered to carry both
C-information
and
Q-information
in
the sense that the conformation of the enzyme can be either in the 0 (or substrate-
bound) state, the 1 (or product-bound) state, or in the (0/1) state at the transition state,
the state in which the active site conformation of the enzyme forces substrate S and
product P to lose their identities and assume an intermediate configuration/conforma-
tion designated as (S
,
P). We may represent this idea diagrammatically as follows:
z
S
E(0
Þ$ð
½
S
,
P
Þ
E(0
=
1
Þ
$
P
E(1)
ð
C - State
Þ
(Q - State)
(C - State)
(4.21)
P) denotes the
metastable
structure
or the
resonance hybrid,
intermediate between substrate and product, and
E(0), E(0/1), and E(1) indicate the enzyme conformations that binds S, the transi-
tion intermediate, (S
,
where S and P are the substrate and the product, (S
P), and P, respectively, and the symbol [ . . .]
{
indicates the
transition state conformation of the enzyme. In other words, the transition state of
the enzyme-ligand complex can be treated as the superposition of the substrate-
binding and the product-binding conformations, reminiscent of the ability of a
quantum object (quon or wavicle) to be in two places at the same time, a phenome-
non called the “nonlocality” in quantum physics (Herbert 1987).
The C- and
Q-states indicate the conformational states of the enzyme where the classical (C)
and quantum (Q) mechanical laws, respectively, are postulated to apply, thus
providing a possible answer to the question raised by H. Frauenfelder in
(Abbott
et al. 2009, p. 366 )
about the relative importance of the classical and quantum
If this description of enzyme catalysis is correct, we can view enzymes as carriers
of quantum information or as quantum computers powered by the free energy of
ligand-binding transformations. When a substrate binds to an enzyme or a hormone
to a receptor, we can say that the substrate or the hormone has meaning for the
enzyme and the receptor, since the latter recognizes the former. A messenger being
recognized by (or meaningful to) its receptor is necessary but not sufficient to
implement the information carried by the messenger. To effectuate (or implement,
or reify) the information, it is necessary to transform the information into a form that
can be recognized by the associated “effector” mechanisms so as to transform the
,
