Oscillatory Control of Glycolysis as Model for Timing Processes
215
20. HIGGINS, J.: Proc. Nat!. Acad. Sci. 51,989 (1964).
21. ATKINSON, D. E.: Regulation of Enzyme Activity. In: Annual Review of
Biochemistry 35, 611 (1966).
22. MOORE, C. L., A. BETZ and B. CHANCE: In: Control of Energy Metabolism
(B. CHANCE, R. W. ESTABROOK and J. R. WILLIAMSON, eds.), p. 97. New
York 1965.
23. BETZ, A., and C. L. ,VIOORE: ABB 120, 268 (1967).
Discussion
SnION:
What about a system of differential equations which describe the process and
behave oscillatory (undamped), as e.g. GOODWIN'S theoretical system?
BETZ:
This was done, as far as I know, by Dr. HIGGINS in Dr. CHANCE'S laboratory
in Philadelphia as well as by Dr. SEL'KOV in Moskow.
S~IITH :
To what extent dues the uncuntrolled step from DAP to iX-glycerophosphate
affect the oscillatory behavior of DPNH?
BETZ:
The shunt from DAP to glycerol is actually participating, the flux being somewhat like 10% of ethanol production. But we could not decide whether it is
uscillatory, too.
WALTER:
Do whole yeast cells that arc not synchronized exhibit oscillations?
BETZ:
The yeast cells are actually synchronized by our treatment, by feeding or by
switching over to anaerobic conditions. But from an experiment with a single
cell, Dr. CHANCE recently told me, it is evident that damping is merely a
population effect and is less efficient in single cells.
KACSER:
I would like to ask you about something I have not quite understood: the
rationale of the phase shift pattern and the assignment of control point effects.
BETZ:
A phase shift of 180
0
between F-6-P and FDP would be a perfect proof that
PFK is the main regulatory point, if we could assume the rate of glucose
incorporation to be constant. Since we know now that phosphorylation of
glucose is a pulsatory process, too, we have to consider that PFK may well be
controlled by F-6-P-concentration rather than by product activation.
ARLEY:
As a physicist I am most interested in your experiments because, as you know,
the concepts of time and ageing are fundamental and for more than 40 years
it has been thought that relativity theory could elucidate the biological aspects
of these problems, predicting that space travellers at relativistic velocities
should get younger as compared with their twin brothers resting on the earth
215
20. HIGGINS, J.: Proc. Nat!. Acad. Sci. 51,989 (1964).
21. ATKINSON, D. E.: Regulation of Enzyme Activity. In: Annual Review of
Biochemistry 35, 611 (1966).
22. MOORE, C. L., A. BETZ and B. CHANCE: In: Control of Energy Metabolism
(B. CHANCE, R. W. ESTABROOK and J. R. WILLIAMSON, eds.), p. 97. New
York 1965.
23. BETZ, A., and C. L. ,VIOORE: ABB 120, 268 (1967).
Discussion
SnION:
What about a system of differential equations which describe the process and
behave oscillatory (undamped), as e.g. GOODWIN'S theoretical system?
BETZ:
This was done, as far as I know, by Dr. HIGGINS in Dr. CHANCE'S laboratory
in Philadelphia as well as by Dr. SEL'KOV in Moskow.
S~IITH :
To what extent dues the uncuntrolled step from DAP to iX-glycerophosphate
affect the oscillatory behavior of DPNH?
BETZ:
The shunt from DAP to glycerol is actually participating, the flux being somewhat like 10% of ethanol production. But we could not decide whether it is
uscillatory, too.
WALTER:
Do whole yeast cells that arc not synchronized exhibit oscillations?
BETZ:
The yeast cells are actually synchronized by our treatment, by feeding or by
switching over to anaerobic conditions. But from an experiment with a single
cell, Dr. CHANCE recently told me, it is evident that damping is merely a
population effect and is less efficient in single cells.
KACSER:
I would like to ask you about something I have not quite understood: the
rationale of the phase shift pattern and the assignment of control point effects.
BETZ:
A phase shift of 180
0
between F-6-P and FDP would be a perfect proof that
PFK is the main regulatory point, if we could assume the rate of glucose
incorporation to be constant. Since we know now that phosphorylation of
glucose is a pulsatory process, too, we have to consider that PFK may well be
controlled by F-6-P-concentration rather than by product activation.
ARLEY:
As a physicist I am most interested in your experiments because, as you know,
the concepts of time and ageing are fundamental and for more than 40 years
it has been thought that relativity theory could elucidate the biological aspects
of these problems, predicting that space travellers at relativistic velocities
should get younger as compared with their twin brothers resting on the earth