Vol. 178, No. 2, 1991 July 31, 1991
KINETIC
BIOCHEMICAL
STUDIES
Gilbert0
Instituto Medicina,
Received
May
AND BIOPHYSICAL RESEARCH COMMUNICATIONS Pages 672-678
OF HUMAN POLYMORPHONUCLEAR PHOSPHOFRUCTOKINASE
Campos,
Elena Ryder*, Luz Marina and Xiomara Raleigh
de Investigaciones Clinicas, Universidad de1 Zulia, Apartado Venezuela
27,
LEUKOCYTE
Morales
Facultad de 1151, Maracaibo
1991
Phosphofructokinase from human polymorphonuclear leukocytes has low cooperativity and high affinity for its substrate, F-6-P. It is resistant to ATP inhibition at pH 8; however, at pH 7.1 it becomes sensitive to the effect of this compound. It is activated by F-1,6-P2; it is not very sensitive to citrate inhibition and F-2,6-P2 has no effect on its activity. With these kinetic characteristics we assume that perhaps the predominant L-type subunit is accompanied by an F-type component. 0 1991 Academic Press, Inc. Phosphofructokinase se,
EC 2.7.1.11),
losteric
ATP and citrate
In
(M),
liver
the
regulated
as inhibitors
humans
It
there
(L)
predominant
glycolytic
isozyme has been
granulocyte
by different
an increased
the
three
basic (F).
in human
entities
characterized are
susceptibility
rate
*TO whom correspondence
that
should
0006-291X/91 $1.50 Copyright 0 1991 by Academic Press, Inc. All rights of reproduction in any form reserved.
as well
in
PMN leukocytes
of glycolysis
is
both
to be the
from
(3).
as in
obesity
resistance, conditions
Since
decreased,
be addressed.
672
seems
by insulin since
muscle
leukocytes
to infection. in
types:
L isozyme
diabetes,
impaired
(F-
as activators
polymorphonuclear in
(6)
6-bisphosphate
PKF isozyme Type
that
has established
diabetics,
are
has al-
metabolites
(F-2,6-P2)
reported
reactions
pathway,
and fructose-l,
and fibroblast
two pathological
(4)
being
in
and fructose-2,6-bisphosphate
(2).
is
ATP-D-Fructose-6-Phosphotransfera-
a key enzyme
properties,
1,6-P2)
(PFK;
insulin defect
there
1972,
Esmann deprived
that
was
Vol.
178,
No.
2, 1991
corrected shown
upon that
BIOCHEMICAL
treatment
glucose
with
oxidation
AND
BIOPHYSICAL
insulin in
RESEARCH
and Kjosen
leukocytes
COMMUNICATIONS
and col(5)
from
obese
have
subjects
was reduced. Timmers reported cytes be able
and co1 (6)
an important isolated
from
to study
PFK activity
in
some extent
the
some kinetic isolated
the
decrease patients
diabetics,
EXPERIMENTAL
as our
in with
mechanism
the
normal
II
responsible
we decided
laboratory
activity
Type
polymorphonuclear
properties from
as well
first
have
of PFK from
diabetes. for
this
In
reporting
decrease
crude
extracts
in
leuko-
order
to characterize
enzyme,
of PFK from
(7)
to in to
this
paper
of granulccytes
individuals.
PROCEDURE
Polymorphonuclear leukocytes (PMN) were Isolation of the cells. isolated from 20 ml of blood of normal individuals, by a Dextran flotation technique, using Dextran T-500 (Pharmacia, Uppsala, Sweden) as described previously (8). The viability of the cells, checked by the Trypan Blue exclusion method was over 90%, being more than 95% PMN. The isolated cells were finally suspended in a cold solution containing 4 mmol/l EDTA, 1 mmol/l benzamidine, 0.1 mmol/l phenylmethylsulfonylflouride (PMSF) and 1 mmol/l DTT, pH 7 (8) and homogenized in a Polytron, two times for 15 sec. Kinetic studies. Reaction mixtures for kinetic studies contained Tris-HCl 33 mM, pH 8; MgS04, 5 mM; NADH, 0.16 mM; KCl, 50 mM; 0.16 IU/ml glycerophosphate dehyDTT, 1 t&l; 2 Ill/ml of aldolase; F-6-P drogenase; 6 IU/ml triosephosphate isomerase. To measure kinetics, the concentration of the substrate varied from 0.0662.66 mM, keeping constant ATP (2 mM). For ATP kinetics, the concentrations used were 0.033-3 mM, keeping constant F-6-P (2 mM). The effects of other effecters were determined at a fixed concentration of F-6-P (2 mM) and ATP (1.5 mM). Citrate was tested from 4-10 mM, F-1,6-P2 from 2-20 uM and F-2,6-P2, from l-80 uM. The reactions were performed at 27oC, pH 8 for non allosteric conditions, and pH 7.1 for allosteric conditions, starting the reaction y the addition of the enzyme extract (@ 40 u total protein Y and the linear decrease in absorbance at 34 8 Ei was measured in a 2400-2 Gilford spectrophotometer. One unit of enzyme is the amount which catalyze the formation of 1 umol of F-1,6-P2 per mg of extract protein, under the abave mentioned conditions. Protein was measured as described by The Lowry and co1 (9) using bovine serum aLbumin as standard. results presented are the average values from 6-9 determinations. which KO.5 is defined as the concentration of substrate produce one-half of the maximum activity. 673
Vol.
178,
No.
2, 1991
BIOCHEMICAL
AND
BIOPHYSICAL
RESEARCH
COMMUNICATIONS
RESULTS Saturation
curves
obtaining At
a Vrax of
pH 7.1,
the
ditions
only
towards
nmol/min/mg
the
curve
and a KO . 5 of
sigmoidicity not
so
of
strong.
42 nmol/min/mg
ATP.
and
inhibition
even
Vmx decreased (0.024
The
and
3)
at
concentrations
0.032
was
hyperbolic,
0.16
mM (Fig
the
1).
allosteric
The
Vmx under
the
K. . 5increased
inhibition
was
This the
decrease
effect
PMN enzyme in
we obtained mM. We could
as
34 mmol/min/mg
that
10 mM, the
pH 8 (Fig.2),
K. . 5 was
inhibition. (Fig
At
the
to
mM).
Citrate
01
pH 8,
en-
these
conto
0.46
1).
Kinetics
at
At
155 nmol/min/mg
although
reached
(Fig
F-6-P.
characteristic
zyme appeared,
ing
for
high
however evident
K. . 5 was
around
0.5
was
resistant only
I
0.5
1.0
1.5
mM 2.0
2.5
2
3.0
0
%-6-P]
I
any
pH 7.1
the
similar
mM.
only
at
pH 7.l,find-
to
this
inhibitor;
20%.
I
II
I
11
I
I
I
0.1 0.2 0.3 0.4 0.5 0.6 0.7 a3 0.a 1.0
IATPl mM
Figure
1. Saturation curves for 0 -0 allosteric and conditions.
fructose-6-phosphate under U0 non-allosteric
Figure
2. Saturation curves pH 7.1 O-O.
ATP at pH 8.0
for
138
observe
the
measured
was
not
of
Vmx
as 3 mM. At
was
activity
a
O-O
and
‘2.0
Vol.
BIOCHEMICAL
178, No. 2, 1991
AND BIOPHYSICAL
RESEARCH COMMUNICATIONS
aE 4 c E 2 ti S >
0
3
1
2
3
4
5
mM 6
7
8
9
0
10
Figure
Effect
2
4
6
8
10
16
18
3. Citrate inhibition curve for human PMN phosphofructokinase. 4. Effect of activators on the PMN phosphofructokinase activity. O- 0 fructose-1,6-bisphosphate and fructose-2,6-bisphosphate. 0 -cl
at pH 7.1.
These
F-1,6-P2
This
activation
city
at
tions
14
12
PM
of activators.
kinetic
was linear,
any important as high
studies
was a potent
a concentration
produce
6-P*
1111111111111111111t
4
[Citrate1
Figure
F-2,
activator
reaching of
as 80 uM (Fig
of
the
100% over
20 uM.
effect
were performed
on the
only
enzyme
its
(Fig
initial
F-2,6-P2,
however,
activity,
even at
4).
velodid
not
concentra-
4).
DISCUSSION In
this
properties
paper
of human
individuals.
weight
loblasts,
the
of
type
Their
gically
seemed
slighty
with
of the
F-type
mainly
antibodies. 675
the
time isolated
in
1979 have is
they
their
crude
activity
Meinhoffer
from
present,
normal that
in
having
leukemyc
extracts
of normal
of L-type
kinetic
reported
used
enzyme showed a single
to be composed
anti
first
of PFK subunit
activity
of magnitudeof
here.
the
Although
80.000.
specific
same order
reported
and co1 (10)
a single
molecular
for
PMN phosphofructokinase
Cottreau
granulocytes,
the
we describe
a
mye-
was
in
granulocytes
band and immunolo-
PFK,
reacting
and co1 (11)
only have
20
BIOCHEMICAL
Vol. 178, No. 2, 1991
studied
some kinetic
mers
L4 from
lets).
They
are
red
this
isozyme,
maximal
properties
cells
found
reporting
with
in
of human M4 (from
their
a not
being
intermediate
between
and F4 with
similar
KO5. was higher than conditions (2.3 vs 0.46).
isozyme
presented for
this
On the L-type
M-type
other
They
affinity
for the
isozyme
F-6-P,
L-rich
isozymes, pronounced
to ATP, inhibited
was less
co1 (11)
In
in
these
effect.
we obtained
under
study,
the
F-type
had a higher
have
components,
placenta
M-type
with
the
subunit
the
characterized M-type
C or F type
Km for
from
lower,
Meinhoffer
and
co1 (11)
found
M4 and F4,
and that
the
than
0.5
mM, effect
and co1 on the sensitive
latter
to ATP than
ones,
the
greatest having
the
that
L4-
inhibition
similar
contrary,
C
fibro-
had the
L-type
and
predominant
cooperativity.
inhibition
reported
were using case,
at a concentration
the
found
previously
found
were completely
their
the
to found
the that
the C-type
ATP inhibition
rich
more
(12).
fer
they
for
presented
and higher
lower
isozyme
been
that
as we
pronounced
co1 (12)
the M-type
than
Dunaway
has not
types
from
the
affinity
The low citrate
and
but
predominant
found.
being
which
less
two minor
that
startsatconcentrations
the
and
being
relation
one we have
Dunaway
(with
concluded
is more
M4,
their
F-6-P
and the
lowest
In
In
F-6-P, at pH 7,
values
Kg5. for
one isolated
muscle
blasts.
F-type
hand,
enzyme
as the
from
the
plate-
substrate.
enriched
or F type)
toward
a far
homotetra-
and F4 (from
cooperativity
their
affinity
PFK comparing
studies
so strong
similar
RESEARCH COMMUNICATIONS
muscle)
kinetic
here,
cooperativity,
However,
AND BIOPHYSICAL
that
at
in
by other
However,
suboptimal
concentrations
sensitive
of F-6-P
was F4.
similar 676
to our
granulocyte
authors,
1 mM citrate,
inhibited.
leas-t
the
it
since
all
the
is
important of F-6-P
Tejedor conditions
PFK Meinhofisozyme to note (0.5
mM).
and co1 (13) (2 mM) and
Vol.
178, No. 2, 1991
1.5
mM ATP,
rat
bone
found
marrow
The report
BIOCHEMICAL
that cell
lack
of
AND BIOPHYSKAL
6 mM citrate
effect
of F-2,6-P2
(14)
that
as supply
of energy,
does
any role
as activator.
In
conclusion,
and a higher for
other
ATP inhibition the
of
inhibition
and
With
in
the
its
other
the
compound.
F-2,6-P2
these
such
human
that as the
to
tissues.
It
at is
F-6-P,
not
very
by a F-type
subunit
component
than
sensitive
the
reported
resistant
to
sensitive
to
to citrate
activity. we might
of
F-2,6-P2
low cooperativity
becomes
on its
characteristics, L-type
it
exclusively
leukocyte,
is completely
pH 7.1
by the
depend
PMN presented
substrate,
It
be explained
tissues
has no effect
kinetic
predominant
be accompanied kinetic
for
at pH 8, however
effect
perhaps
PFK from
affinity authors
50% inhibition
might
in
on glycolysis play
produced
enzyme.
of Hue & Rider
not
RESEARCH COMMUNICATIONS
granulocyte
responsible
for
conclude
that
PFK might some of
its
behavior.
ACKNOWLEDGMENT To Consejo de1 Zulia
de Desarrollo Cientifico y CONICIT, Venezuela, for
y Humanistico, Universidad financial support.
REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9c
Akkerman, J.W.N., Gorter, G., Sixma, J.J. and Stall. G.E.J. (1974). Int. J. Biochem. 5, 853-857. Van Schaftingen, E., Hue, L. and Hers, H.G. (1980) Biochem J. 192, 897-901. Kahn, A., Meinhoffer,M.C., Cottreau, D., Lagrange, J.L. and Dreyfus, J.C. (1979) Hum. Genet. 48, 93-108. Esmann, V. (1972) Enzyme 13, 32-55. Hjosen, B., Bassdeh, H. and Mycin, S.O. (1975) Stand. J. Clin Lab. Invest. 35, 447-454. Timmers, K.I., Dons, R., Grunberger, g. and Hodge, J. (1986) Enzyme 36, 247-253. L.M. (1987)BioRyder, E., Campos, G. and Morales-Villalobos, them. Medic. Metabol. Biol. 37, 205-217. Ryder, E. and Martinucci, D. (1977) Invest. Clin. 18, 108-122. Farr, A.L. and Randall, R.J. Lowry, O.H.? Rosebrough, H.J., (1951) J. Biol. Chem. 193, 265-275. 677
Vol.
10. 11. 12. 13. 14.
178,
No.
2, 1991
BIOCHEMICAL
AND
BIOPHYSICAL
RESEARCH
COMMUNICATIONS
Cottreau, D., Levin, M.J. and Kahn, A. (1979) Biochim. Biophys. Acta 568, 183-194. Meinhoffer, M.C., Cottreau, D., Dreyfus, J.C. and Kahn, A. (1980) FEBS lett. 110, 219-222. Duanway, G.A., Kasten, T.P., Sebo, T. and Trapp, R. (1988) Biochem. J. 251, 677-683. Tejedor, M.C., Ramirez, A. and Luque, J. (1984) Biochem. Int. 9, 577-586. Hue, L. and Rider, M.H. (1987) Biochem. J. 245, 313-324.
678
KINETIC
BIOCHEMICAL
STUDIES
Gilbert0
Instituto Medicina,
Received
May
AND BIOPHYSICAL RESEARCH COMMUNICATIONS Pages 672-678
OF HUMAN POLYMORPHONUCLEAR PHOSPHOFRUCTOKINASE
Campos,
Elena Ryder*, Luz Marina and Xiomara Raleigh
de Investigaciones Clinicas, Universidad de1 Zulia, Apartado Venezuela
27,
LEUKOCYTE
Morales
Facultad de 1151, Maracaibo
1991
Phosphofructokinase from human polymorphonuclear leukocytes has low cooperativity and high affinity for its substrate, F-6-P. It is resistant to ATP inhibition at pH 8; however, at pH 7.1 it becomes sensitive to the effect of this compound. It is activated by F-1,6-P2; it is not very sensitive to citrate inhibition and F-2,6-P2 has no effect on its activity. With these kinetic characteristics we assume that perhaps the predominant L-type subunit is accompanied by an F-type component. 0 1991 Academic Press, Inc. Phosphofructokinase se,
EC 2.7.1.11),
losteric
ATP and citrate
In
(M),
liver
the
regulated
as inhibitors
humans
It
there
(L)
predominant
glycolytic
isozyme has been
granulocyte
by different
an increased
the
three
basic (F).
in human
entities
characterized are
susceptibility
rate
*TO whom correspondence
that
should
0006-291X/91 $1.50 Copyright 0 1991 by Academic Press, Inc. All rights of reproduction in any form reserved.
as well
in
PMN leukocytes
of glycolysis
is
both
to be the
from
(3).
as in
obesity
resistance, conditions
Since
decreased,
be addressed.
672
seems
by insulin since
muscle
leukocytes
to infection. in
types:
L isozyme
diabetes,
impaired
(F-
as activators
polymorphonuclear in
(6)
6-bisphosphate
PKF isozyme Type
that
has established
diabetics,
are
has al-
metabolites
(F-2,6-P2)
reported
reactions
pathway,
and fructose-l,
and fibroblast
two pathological
(4)
being
in
and fructose-2,6-bisphosphate
(2).
is
ATP-D-Fructose-6-Phosphotransfera-
a key enzyme
properties,
1,6-P2)
(PFK;
insulin defect
there
1972,
Esmann deprived
that
was
Vol.
178,
No.
2, 1991
corrected shown
upon that
BIOCHEMICAL
treatment
glucose
with
oxidation
AND
BIOPHYSICAL
insulin in
RESEARCH
and Kjosen
leukocytes
COMMUNICATIONS
and col(5)
from
obese
have
subjects
was reduced. Timmers reported cytes be able
and co1 (6)
an important isolated
from
to study
PFK activity
in
some extent
the
some kinetic isolated
the
decrease patients
diabetics,
EXPERIMENTAL
as our
in with
mechanism
the
normal
II
responsible
we decided
laboratory
activity
Type
polymorphonuclear
properties from
as well
first
have
of PFK from
diabetes. for
this
In
reporting
decrease
crude
extracts
in
leuko-
order
to characterize
enzyme,
of PFK from
(7)
to in to
this
paper
of granulccytes
individuals.
PROCEDURE
Polymorphonuclear leukocytes (PMN) were Isolation of the cells. isolated from 20 ml of blood of normal individuals, by a Dextran flotation technique, using Dextran T-500 (Pharmacia, Uppsala, Sweden) as described previously (8). The viability of the cells, checked by the Trypan Blue exclusion method was over 90%, being more than 95% PMN. The isolated cells were finally suspended in a cold solution containing 4 mmol/l EDTA, 1 mmol/l benzamidine, 0.1 mmol/l phenylmethylsulfonylflouride (PMSF) and 1 mmol/l DTT, pH 7 (8) and homogenized in a Polytron, two times for 15 sec. Kinetic studies. Reaction mixtures for kinetic studies contained Tris-HCl 33 mM, pH 8; MgS04, 5 mM; NADH, 0.16 mM; KCl, 50 mM; 0.16 IU/ml glycerophosphate dehyDTT, 1 t&l; 2 Ill/ml of aldolase; F-6-P drogenase; 6 IU/ml triosephosphate isomerase. To measure kinetics, the concentration of the substrate varied from 0.0662.66 mM, keeping constant ATP (2 mM). For ATP kinetics, the concentrations used were 0.033-3 mM, keeping constant F-6-P (2 mM). The effects of other effecters were determined at a fixed concentration of F-6-P (2 mM) and ATP (1.5 mM). Citrate was tested from 4-10 mM, F-1,6-P2 from 2-20 uM and F-2,6-P2, from l-80 uM. The reactions were performed at 27oC, pH 8 for non allosteric conditions, and pH 7.1 for allosteric conditions, starting the reaction y the addition of the enzyme extract (@ 40 u total protein Y and the linear decrease in absorbance at 34 8 Ei was measured in a 2400-2 Gilford spectrophotometer. One unit of enzyme is the amount which catalyze the formation of 1 umol of F-1,6-P2 per mg of extract protein, under the abave mentioned conditions. Protein was measured as described by The Lowry and co1 (9) using bovine serum aLbumin as standard. results presented are the average values from 6-9 determinations. which KO.5 is defined as the concentration of substrate produce one-half of the maximum activity. 673
Vol.
178,
No.
2, 1991
BIOCHEMICAL
AND
BIOPHYSICAL
RESEARCH
COMMUNICATIONS
RESULTS Saturation
curves
obtaining At
a Vrax of
pH 7.1,
the
ditions
only
towards
nmol/min/mg
the
curve
and a KO . 5 of
sigmoidicity not
so
of
strong.
42 nmol/min/mg
ATP.
and
inhibition
even
Vmx decreased (0.024
The
and
3)
at
concentrations
0.032
was
hyperbolic,
0.16
mM (Fig
the
1).
allosteric
The
Vmx under
the
K. . 5increased
inhibition
was
This the
decrease
effect
PMN enzyme in
we obtained mM. We could
as
34 mmol/min/mg
that
10 mM, the
pH 8 (Fig.2),
K. . 5 was
inhibition. (Fig
At
the
to
mM).
Citrate
01
pH 8,
en-
these
conto
0.46
1).
Kinetics
at
At
155 nmol/min/mg
although
reached
(Fig
F-6-P.
characteristic
zyme appeared,
ing
for
high
however evident
K. . 5 was
around
0.5
was
resistant only
I
0.5
1.0
1.5
mM 2.0
2.5
2
3.0
0
%-6-P]
I
any
pH 7.1
the
similar
mM.
only
at
pH 7.l,find-
to
this
inhibitor;
20%.
I
II
I
11
I
I
I
0.1 0.2 0.3 0.4 0.5 0.6 0.7 a3 0.a 1.0
IATPl mM
Figure
1. Saturation curves for 0 -0 allosteric and conditions.
fructose-6-phosphate under U0 non-allosteric
Figure
2. Saturation curves pH 7.1 O-O.
ATP at pH 8.0
for
138
observe
the
measured
was
not
of
Vmx
as 3 mM. At
was
activity
a
O-O
and
‘2.0
Vol.
BIOCHEMICAL
178, No. 2, 1991
AND BIOPHYSICAL
RESEARCH COMMUNICATIONS
aE 4 c E 2 ti S >
0
3
1
2
3
4
5
mM 6
7
8
9
0
10
Figure
Effect
2
4
6
8
10
16
18
3. Citrate inhibition curve for human PMN phosphofructokinase. 4. Effect of activators on the PMN phosphofructokinase activity. O- 0 fructose-1,6-bisphosphate and fructose-2,6-bisphosphate. 0 -cl
at pH 7.1.
These
F-1,6-P2
This
activation
city
at
tions
14
12
PM
of activators.
kinetic
was linear,
any important as high
studies
was a potent
a concentration
produce
6-P*
1111111111111111111t
4
[Citrate1
Figure
F-2,
activator
reaching of
as 80 uM (Fig
of
the
100% over
20 uM.
effect
were performed
on the
only
enzyme
its
(Fig
initial
F-2,6-P2,
however,
activity,
even at
4).
velodid
not
concentra-
4).
DISCUSSION In
this
properties
paper
of human
individuals.
weight
loblasts,
the
of
type
Their
gically
seemed
slighty
with
of the
F-type
mainly
antibodies. 675
the
time isolated
in
1979 have is
they
their
crude
activity
Meinhoffer
from
present,
normal that
in
having
leukemyc
extracts
of normal
of L-type
kinetic
reported
used
enzyme showed a single
to be composed
anti
first
of PFK subunit
activity
of magnitudeof
here.
the
Although
80.000.
specific
same order
reported
and co1 (10)
a single
molecular
for
PMN phosphofructokinase
Cottreau
granulocytes,
the
we describe
a
mye-
was
in
granulocytes
band and immunolo-
PFK,
reacting
and co1 (11)
only have
20
BIOCHEMICAL
Vol. 178, No. 2, 1991
studied
some kinetic
mers
L4 from
lets).
They
are
red
this
isozyme,
maximal
properties
cells
found
reporting
with
in
of human M4 (from
their
a not
being
intermediate
between
and F4 with
similar
KO5. was higher than conditions (2.3 vs 0.46).
isozyme
presented for
this
On the L-type
M-type
other
They
affinity
for the
isozyme
F-6-P,
L-rich
isozymes, pronounced
to ATP, inhibited
was less
co1 (11)
In
in
these
effect.
we obtained
under
study,
the
F-type
had a higher
have
components,
placenta
M-type
with
the
subunit
the
characterized M-type
C or F type
Km for
from
lower,
Meinhoffer
and
co1 (11)
found
M4 and F4,
and that
the
than
0.5
mM, effect
and co1 on the sensitive
latter
to ATP than
ones,
the
greatest having
the
that
L4-
inhibition
similar
contrary,
C
fibro-
had the
L-type
and
predominant
cooperativity.
inhibition
reported
were using case,
at a concentration
the
found
previously
found
were completely
their
the
to found
the that
the C-type
ATP inhibition
rich
more
(12).
fer
they
for
presented
and higher
lower
isozyme
been
that
as we
pronounced
co1 (12)
the M-type
than
Dunaway
has not
types
from
the
affinity
The low citrate
and
but
predominant
found.
being
which
less
two minor
that
startsatconcentrations
the
and
being
relation
one we have
Dunaway
(with
concluded
is more
M4,
their
F-6-P
and the
lowest
In
In
F-6-P, at pH 7,
values
Kg5. for
one isolated
muscle
blasts.
F-type
hand,
enzyme
as the
from
the
plate-
substrate.
enriched
or F type)
toward
a far
homotetra-
and F4 (from
cooperativity
their
affinity
PFK comparing
studies
so strong
similar
RESEARCH COMMUNICATIONS
muscle)
kinetic
here,
cooperativity,
However,
AND BIOPHYSICAL
that
at
in
by other
However,
suboptimal
concentrations
sensitive
of F-6-P
was F4.
similar 676
to our
granulocyte
authors,
1 mM citrate,
inhibited.
leas-t
the
it
since
all
the
is
important of F-6-P
Tejedor conditions
PFK Meinhofisozyme to note (0.5
mM).
and co1 (13) (2 mM) and
Vol.
178, No. 2, 1991
1.5
mM ATP,
rat
bone
found
marrow
The report
BIOCHEMICAL
that cell
lack
of
AND BIOPHYSKAL
6 mM citrate
effect
of F-2,6-P2
(14)
that
as supply
of energy,
does
any role
as activator.
In
conclusion,
and a higher for
other
ATP inhibition the
of
inhibition
and
With
in
the
its
other
the
compound.
F-2,6-P2
these
such
human
that as the
to
tissues.
It
at is
F-6-P,
not
very
by a F-type
subunit
component
than
sensitive
the
reported
resistant
to
sensitive
to
to citrate
activity. we might
of
F-2,6-P2
low cooperativity
becomes
on its
characteristics, L-type
it
exclusively
leukocyte,
is completely
pH 7.1
by the
depend
PMN presented
substrate,
It
be explained
tissues
has no effect
kinetic
predominant
be accompanied kinetic
for
at pH 8, however
effect
perhaps
PFK from
affinity authors
50% inhibition
might
in
on glycolysis play
produced
enzyme.
of Hue & Rider
not
RESEARCH COMMUNICATIONS
granulocyte
responsible
for
conclude
that
PFK might some of
its
behavior.
ACKNOWLEDGMENT To Consejo de1 Zulia
de Desarrollo Cientifico y CONICIT, Venezuela, for
y Humanistico, Universidad financial support.
REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9c
Akkerman, J.W.N., Gorter, G., Sixma, J.J. and Stall. G.E.J. (1974). Int. J. Biochem. 5, 853-857. Van Schaftingen, E., Hue, L. and Hers, H.G. (1980) Biochem J. 192, 897-901. Kahn, A., Meinhoffer,M.C., Cottreau, D., Lagrange, J.L. and Dreyfus, J.C. (1979) Hum. Genet. 48, 93-108. Esmann, V. (1972) Enzyme 13, 32-55. Hjosen, B., Bassdeh, H. and Mycin, S.O. (1975) Stand. J. Clin Lab. Invest. 35, 447-454. Timmers, K.I., Dons, R., Grunberger, g. and Hodge, J. (1986) Enzyme 36, 247-253. L.M. (1987)BioRyder, E., Campos, G. and Morales-Villalobos, them. Medic. Metabol. Biol. 37, 205-217. Ryder, E. and Martinucci, D. (1977) Invest. Clin. 18, 108-122. Farr, A.L. and Randall, R.J. Lowry, O.H.? Rosebrough, H.J., (1951) J. Biol. Chem. 193, 265-275. 677
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10. 11. 12. 13. 14.
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No.
2, 1991
BIOCHEMICAL
AND
BIOPHYSICAL
RESEARCH
COMMUNICATIONS
Cottreau, D., Levin, M.J. and Kahn, A. (1979) Biochim. Biophys. Acta 568, 183-194. Meinhoffer, M.C., Cottreau, D., Dreyfus, J.C. and Kahn, A. (1980) FEBS lett. 110, 219-222. Duanway, G.A., Kasten, T.P., Sebo, T. and Trapp, R. (1988) Biochem. J. 251, 677-683. Tejedor, M.C., Ramirez, A. and Luque, J. (1984) Biochem. Int. 9, 577-586. Hue, L. and Rider, M.H. (1987) Biochem. J. 245, 313-324.
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