Free software for complex kinetics and equilibria
pkuzmic at biokin.com
Wed Sep 17 07:43:21 EST 1997
Program D Y N A F I T U P D A T E
Public domain program DynaFit for the analysis and simula-
tion of enzyme kinetic and receptor binding data was upda-
ted to version 2.17.5 (09/16/97).
'RAPID-EQUILIBRIUM' ENZYME KINETICS
The notation for enzyme mechanisms analyzed under the
'rapid-equilibrium approximation' was simplified. We no
longer have to specify both dissociation and association
rate constants for each reaction step. Instead, the newly
introduced keywords ASSOC and DISSOC allow the definition
of association and dissociation equilibrium constants. An
example problem is based on the initial velocities for ami-
nopeptidase B (from the laboratory of Prof. D.H. Rich).The
most plausible inhibition mechanism (partial, noncompeti-
tive, double-site) is notated as follows:
E + S <==> ES : Ks dissoc.
ES ---> E + P : kcat
E + I <==> EI : Ki dissoc.
ES + I <==> ESI : Kis dissoc.
ESI ---> EI + P : kcat'
EI + I <==> EI2 : Ki2 dissoc.
It is important that the inhibitor can be 'tight-binding'.
See directory ./TEST/AMIPEP-B in the test problem archive.
The usefulness of the program DynaFit for enzyme and recep-
tor studies is obvious, but the following applications are
interesting in that they come from neighboring disciplines.
** CYTOFLUORIMETRY: DYNAMICS OF FLUORESCENT PHOTOBLEACHING
A zoologist working at an Italian university wrote:
"I wish to express to you my gratitude for making available
your program Dynafit. I think it works really great! I am
using it to study the bleaching kinetics of fluorophores
in cytofluorimetry, which appears to involve several concom-
itant and successive reversible and irreveversible reac-
tions. Indeed, solving analytically the underlying system
of differential equations would be extremely complicated."
** INDUSTRIAL REACTOR KINETICS: IMMOBILIZED ENZYMES
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