AMBER Archive (2009)

Subject: [AMBER] too high in binding energy (MM-PBSA)

From: Maryam Hamzehee (maryam_h_7860_at_yahoo.com)
Date: Sat Jun 13 2009 - 04:53:43 CDT

Dear All
I am doing a simulation to calculate binding energy for a complex almost in a similar way to that mentioned for “Tutorial A3: MM-PBSA”.  I have performed the MD for the ligand-protein complex up to 4ns, the results are shown below:
 
#                  COMPLEX                RECEPTOR                  LIGAND
#          ----------------------- ----------------------- --------------------- 

--
#                  MEAN        STD         MEAN        STD         MEAN        S
TD
#          ======================= ======================= =====================
==
ELE           -17522.63     140.50    -15680.04     175.32     -1464.72      72.88
VDW            -2184.97      35.92     16218.97      94.50   1019955.82   28749.20
INT            11460.75      67.35     10503.06      63.03   3397603.93  535323.59
GAS            -8246.85     147.21     11041.99     212.12   4416095.03  537408.13
PBSUR            211.35       1.93       203.32       1.85        33.58       0.64
PBCAL          -6424.57     128.02     -6187.77     156.53     -2137.68     213.57
PBSOL          -6213.22     127.07     -5984.45     155.42     -2104.10     213.53
PBELE         -23947.20      46.55    -21867.81      47.02     -3602.40     205.89
PBTOT         -14460.07      68.33      5057.54     112.99   4413990.93  537351.27
GBSUR            211.35       1.93       203.32       1.85        33.58       0.64
GB             -6537.48     130.17     -6309.73     157.62     -1630.23      44.54
GBSOL          -6326.13     129.22     -6106.41     156.51     -1596.65      44.33
GBELE         -24060.11      39.42    -21989.77      40.38     -3094.95      62.88
GBTOT         -14572.98      67.59      4935.58     113.98   4414498.38  537397.88
#                    DELTA
#          -----------------------
#                  MEAN        STD
#          =======================
ELE             -377.88     122.64
VDW         -1038359.76   28742.84
INT         -3396646.24  535320.32
GAS         -4435383.87  537455.24
PBSUR            -25.56       1.02
PBCAL           1900.89     247.22
PBSOL           1875.33     246.84
PBELE           1523.01     204.69
PBTOT       -4433508.54  537355.75
GBSUR            -25.56       1.02
GB              1402.49     122.13
GBSOL           1376.93     121.44
GBELE           1024.61      62.02
GBTOT       -4434006.94  537403.59
 
As far as I concerned the PBTOT shows the total binding free energy, in our calculation PBTOT is -4433508.54. It is highly negative. I think the large amount of this figure is related to ligand, what is wrong with my simulation.
 
Any help in this regard would be highly appreciated,
 
Cheers,
Maryam
 

      
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