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<DIV><FONT face=Arial size=2><SPAN class=158490812-17062007>I want to simulated
transport of D- and L- alanine molecules. First I tried using ffg43a1 force
field, but D-analine will quickly flip to L-alanine during energy minimization
(I dont know why). Alternatively, I tried oplsaa force fields. That's OK without
flip from D- to L-. But one problem is that when I used</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=158490812-17062007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=158490812-17062007>pdb2gmx -f
L_alanine.pdb -p L_alanine.top -o L_alanine.gro -ff oplsaa</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=158490812-17062007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=158490812-17062007>The produced
L_alanine.top showed that L_alanine molecule has non-integral charge, which is
obvioulsy unrealisitc.</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=158490812-17062007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=158490812-17062007>[ atoms
]<BR>; nr type resnr
residue atom cgnr
charge mass typeB
chargeB massB<BR>
1 opls_287 1
ALA N
1 -0.3 14.0067
; qtot -0.3<BR> 2
opls_290 1
ALA H1
1 0.33
1.008 ; qtot 0.03<BR> 3
opls_290 1
ALA H2
1 0.33
1.008 ; qtot 0.36<BR> 4
opls_290 1
ALA H3
1 0.33
1.008 ; qtot 0.69<BR> 5
opls_283 1
ALA CA
1 0.04
12.011 ; qtot 0.73<BR> 6
opls_140 1
ALA HA
1 0.06
1.008 ; qtot 0.79<BR> 7
opls_135 1
ALA CB
2 -0.18 12.011
; qtot 0.61<BR> 8
opls_140 1 ALA
HB1 2
0.06 1.008 ; qtot
0.67<BR> 9
opls_140 1 ALA
HB2 2
0.06 1.008 ; qtot
0.73<BR> 10 opls_140
1 ALA HB3
2 0.06
1.008 ; qtot 0.79<BR> 11
opls_271 1
ALA C
3 0.7
12.011 ; qtot 1.49<BR> 12
opls_272 1
ALA O1
3 -0.8 15.9994
; qtot 0.69<BR> 13
opls_272 1
ALA O2
3 -0.8 15.9994
; qtot -0.11</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=158490812-17062007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=158490812-17062007>I opened
ffoplsaa.rtp and find the atom types for ALA residue is</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=158490812-17062007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=158490812-17062007>[ ALA ]<BR> [
atoms ] <BR> N opls_238
-0.500 1<BR> H
opls_241 0.300 1
<BR> CA opls_224B
0.140 1 <BR> HA
opls_140 0.060 1
<BR> CB opls_135
-0.180 2 <BR> HB1
opls_140 0.060 2 <BR>
HB2 opls_140 0.060 2
<BR> HB3 opls_140
0.060 2 <BR> C
opls_235 0.500
3<BR> O opls_236
-0.500 3</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=158490812-17062007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=158490812-17062007>I found that charges
of atoms in L_alanine molecule are different from charges of corresponding atoms
in ALA residue. I want to ask</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=158490812-17062007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=158490812-17062007>(1) why L_alanine
molecule has non-integral charge? Is it right?</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN class=158490812-17062007>(2)
why identical atoms in L_alanine and ALA residue have different
charges?</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=158490812-17062007></SPAN></FONT> </DIV>
<DIV><FONT face=Arial size=2><SPAN class=158490812-17062007>Thanks in
advance,</SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2><SPAN
class=158490812-17062007> </DIV></SPAN></FONT>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV align=left>
<DIV align=left><FONT face="Times New Roman" size=4>Zhongqiao Hu</FONT></DIV>
<DIV align=left><FONT face="Times New Roman"></FONT> </DIV>
<DIV align=left>
<DIV align=left>
<DIV align=left><FONT face="Times New Roman"></FONT></DIV></DIV><FONT
face="Times New Roman">Department of Chemical and Biomolecular
Engineering</FONT></DIV>
<DIV align=left><FONT face="Times New Roman">National University of
Singapore</FONT></DIV>
<DIV align=left><FONT face="Times New Roman">117576, Singapore</FONT></DIV>
<DIV align=left><FONT face="Times New Roman"></FONT> </DIV></DIV>
<DIV> </DIV></BODY></HTML>