  |   |        PKA | 
 
 
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 Reaction List  for pathway CaMKII (Pathway Number 357) |  | Kd is calculated only for second order reactions, like nA+nB <->nC or nA<->nC+nD, where n is number and A,B,C,D are molecules, where as for first order reactions Keq is calculated. Kd for higher order reactions is not considered. |      |     |  Name  | Kf | Kb | Kd | tau | Substrate | Product |   |  1  | 
  basal-activity | 0.003 (s^-1) | 0 (s^-1) | - | - | CaMKII
  | CaMKII-thr286
  |  |   |   This reaction represents one of the big unknowns in CaMK-II biochemistry: what maintains the basal level of phosphorylation on thr 286 ? See Hanson and Schulman Ann Rev Biochem 1992 61:559-601, specially pg 580, for review. I have not been able to find any compelling mechanism in the literature, but fortunately the level of basal activity is well documented.  |   |  2  | 
  CaMK-thr286-bind -CaM | 1000.17 (uM^-1 s^-1) | 0.1 (s^-1) | Kd(bf) = 0.0001(uM) | - | CaMKII-thr286 CaM-Ca4
  | CaMKII-thr286*-C aM
  |  |   |   Affinity is up 1000X. Time to release is about 20 sec, so the kb is OK at 0.1 This makes Kf around 1.6666e-3  |   |  3  | 
  CaMKII-bind-CaM | 49.9995 (uM^-1 s^-1) | 5 (s^-1) | Kd(bf) = 0.1(uM) | - | CaM-Ca4 CaMKII
  | CaMKII-CaM
  |  |   |   This is tricky. There is some cooperativity here arising from interactions between the subunits of the CAMKII holoenzyme. However, the stoichiometry is 1. Kb/Kf = 6e4 #/cell. Rate is fast (see Hanson et al Neuron 12 943-956 1994) so lets say kb = 10. This gives kf = 1.6667e-4 H&S AnnRev Biochem 92 give tau for dissoc as 0.2 sec at low Ca, 0.4 at high. Low Ca = 100 nM = physiol. |   
 
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