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Accession Type:
Network
CaMKII_model3
Shared_Object_
CaMKII_model3
CaMKII
CaM
PP1
PP2B
PP1_PSD
AC
 Molecule
 Enzyme
 Reaction
PKA

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Enzyme List for pathway AC (Pathway Number 269)

 Molecule Name/
Site Name
Km (uM) kcat (1/s)Ratio
(k2/k3)
Enzyme TypeSubstrate Product
1 Enzyme Activity:
CaM.PDE1

Enzyme Molecule:
CaM.PDE1
39.6831104explicit E-S complexcAMP
AMP
  Max activity ~10umol/min/mg in presence of lots of CaM. Affinity is low, 40 uM. k3 = 10, k2 = 40, k1 = (50/40) / 6e5.
2 Enzyme Activity:
kenz

Enzyme Molecule:
AC1-CaM
299.9984.54Classical Michaelis-Menten
V = Etot.S.Kcat/Km+S
ATP
cAMP
  17 Feb 2005 Halved Vmax as the amount of enzyme has been doubled to get an integer value in the spine. 18 Feb 2005. Updated Km from BRENDA: EC No 4.6.1.1 Rat Km: 0.95 mM Turnover 12/sec. Human Km: 0.3 mM 12 umol/min/mg for mammalia, turnover is 12/sec See PMID 8663304 by Dessauer and Gilman JBC 271 1996 Unfortunately turnover range is from 34 down to 0.1 in different studies, according to BRENDA.
3 Enzyme Activity:
kenz

Enzyme Molecule:
AC2*
300.00224Classical Michaelis-Menten
V = Etot.S.Kcat/Km+S
ATP
cAMP
  Reduced Km to match expt data for basal activation of AC2 by PKC. Now k1 = 2.9e-6, k2 = 72, k3 = 18 18 Feb: Raised Km to 300 based on BRENDA data. Unlikely to make much difference, given the vast amount of ATP.
4 Enzyme Activity:
PDE

Enzyme Molecule:
cAMP-PDE
19.8411104explicit E-S complexcAMP
AMP
  Best rates are from Conti et al Biochem 34 7979-7987 1995. Though these are for the Sertoli cell form, it looks like they carry nicely into alternatively spliced brain form. See Sette et al JBC 269:28 18271-18274 Km ~2 uM, Vmax est ~ 10 umol/min/mg for pure form. Brain protein is 93 kD but this was 67. So k3 ~10, k2 ~40, k1 ~4.2e-6
5 Enzyme Activity:
PDE*

Enzyme Molecule:
cAMP-PDE*
19.8413204explicit E-S complexcAMP
AMP
  This form has about twice the activity of the unphosphorylated form. See Sette et al JBC 269:28 18271-18274 1994. We'll ignore cGMP effects for now.
6 Enzyme Activity:
PDE1

Enzyme Molecule:
PDE1
39.69991.6674.0012explicit E-S complexcAMP
AMP
  Rate is 1/6 of the CaM stim form. We'll just reduce all lf k1, k2, k3 so that the Vmax goes down 1/6.


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