Download II. BIOPHYSICAL CHEMISTRY*

BIOPHYSICAL CHEMISTRY*
II.
Prof. G. G. Hammes
Dr. S. R. Miller
RESEARCH OBJECTIVES AND PRELIMINARY
STUDIES
This project is concerned with the elucidation of the mechanism of physiologically
Very fast reactions
important reactions, primarily through the use of kinetic methods.
involving purified enzymes and simpler model systems will be investigated with the use
of several different techniques.
A stopped-flow apparatus1 permits the study of reactions occurring in times as fast
This method simply involves rapid mixing of the reactants in a spe-
as milliseconds.
cially designed chamber and observation of the mixed solution after the flow has been
The reaction progress is followed through changes either in optical
stopped suddenly.
absorption or optical rotation.
Reactions
occurring
developed
recently
in
even
relaxation
times
shorter
techniques.2,3
by utilizing
will be investigated
principle
The
of these
methods
to disturb chemical equilibria by rapidly changing some external parameter
pressure)
temperature,
librium.
A
and studying
the
apparatus,
temperature-jump
reaction mixture 8°C in approximately 5
jump is
perature
then
tronic
and rotation
accessible
ultrasonic
as a
rapidly
by charging
through the
has
a
reaction
to 30,000
mixture.
Changes
and
with photomultipliers
are followed
of
a
This tem-
been constructed.
condenser
equi-
volts and
in
optical
associated
elec-
equipment.
The
wave
equilibria.
at frequencies
given
time
scale
extended
can be
attenuation in equilibrium reaction
pressure
chemical
a
it
discharging
absorption
accomplished
the temperature
which raises
sec,
of
re-establishment
subsequent
is
(e. g.,
in
aqueous
result
The
that are
related
solution,
is
in
the
a
to
-9
mixtures.
and thus
occurrence
known
10
sec by measurement
The
perturbs
ultrasonic wave acts
pressure-dependent
of maxima
way to the
of
formal
in
the
rate
attenuation
constants
of
mechanism.
These techniques will permit the study of elementary steps in chemical reactions,
and thus provide some details of the molecular mechanism.
Also, rates of fast con-
formational changes in macromolecules can be measured and related to chemical processes.
Preliminary experiments have already been carried out and the results will be
presented in a future report.
G. G. Hammes
This project is
RG-7803).
supported in part by the
National
Institutes
of Health (Grant
(II.
BIOPHYSICAL CHEMISTRY)
References
1.
B. Chance and V. Legallais, Discussions Faraday Soc.
2.
M. Eigen, Z. Elektrochem. 64, 115 (1960).
3.
L. De Maeyer, Z. Elektrochem. 64,
65 (1960).
17,
125 (1954).