[Chimera-users] Adding Partial Charges
Elaine Meng
meng at cgl.ucsf.edu
Mon Jun 14 10:34:26 PDT 2010
Hi Nancy,
The Gasteiger net charge not matching the input value was a bug of Antechamber. We had reported this problem to the Antechamber developers, as discussed here:
<http://www.cgl.ucsf.edu/pipermail/chimera-users/2007-August/001732.html>
However, we're now using a newer version of Antechamber, and I just ran a little Add Charge test in Chimera version 1.5 (current daily build) -- the Gasteiger net charge did match the input value. It may be that the bug is fixed in this version of Antechamber. So I recommend trying the Chimera daily build.
It is not surprising that the charges from the different methods are different. Gasteiger is simpler/faster, and I agree it tends to give smaller charges. AM1-BCC vs. Gasteiger charges have been discussed on other mailing lists, for example the Amber list:
<http://archive.ambermd.org/200806/0449.html>
"Amber ff99SB" only specifies which charges are used for the standard amino acids and nucleic acids, and does not affect the nonstandard residues such as NAD+.
I hope this helps,
Elaine
----------
Elaine C. Meng, Ph.D.
UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab
Department of Pharmaceutical Chemistry
University of California, San Francisco
On Jun 13, 2010, at 5:40 PM, Nancy wrote:
> Hi All,
> I am trying to add charges to nicotinamide adenine dinucleotide (NAD+) using UCSF Chimera; the total charge on this molecule should be -1 (assuming the ionization of NAD+ at pH ~7.0, see attached figure). When I add Gasteiger charges, the total charge sums up incorrectly to 0, even though the net charge specified in the drop-down box is -1. However, using the "AM1-BCC" method, the net charge correctly sums up to -1. The charge model used is "Amber ff99SB". I have also noticed that the partial charges on individual atoms assigned when using the "AM1-BCC" method are generally of greater magnitude compared to charges assigned using the Gasteiger method.
>
> I am wondering why the Gasteiger method assigns an incorrect net charge in the case of NAD+.
>
> The mol2 structure code (with incorrect Gasteiger charges) is written below (and attached as NAD.mol2 with corresponding PNG structure image).
>
> Thanks in advance,
> Nancy
>
> ============================================================================
> @<TRIPOS>MOLECULE
> NAD.mol2
> 70 74 1 0 0
> SMALL
> USER_CHARGES
>
>
> @<TRIPOS>ATOM
> 1 C1 -1.4117 5.8700 -3.4377 C.2 1 LIG1 -0.0471
> 2 C2 -0.2808 5.1989 -2.9922 C.2 1 LIG1 -0.0472
> 3 C3 0.0698 5.2540 -1.6463 C.2 1 LIG1 -0.0021
> 4 N1 -0.7125 5.8930 -0.7233 N.2 1 LIG1 -0.2845
> 5 C4 -1.7621 6.6431 -1.1880 C.2 1 LIG1 0.0105
> 6 C5 -2.1590 6.6215 -2.5315 C.2 1 LIG1 0.0510
> 7 C6 -3.3433 7.3892 -2.9991 C.2 1 LIG1 0.2416
> 8 O1 -3.7255 7.3875 -4.2002 O.2 1 LIG1 -0.2721
> 9 N2 -4.0978 8.1475 -2.0847 N.3 1 LIG1 -0.3250
> 10 O2 0.0324 4.4339 0.9916 O.3 1 LIG1 -0.3484
> 11 C7 -1.0355 3.6965 1.6402 C.3 1 LIG1 0.1165
> 12 C8 -1.4243 2.4599 0.8071 C.3 1 LIG1 0.1276
> 13 O3 -0.4100 1.4351 0.9207 O.3 1 LIG1 -0.1602
> 14 P1 0.8613 1.4216 -0.0633 P.3 1 LIG1 0.5624
> 15 O4 2.0180 2.1020 0.5580 O.2 1 LIG1 -0.3429
> 16 O5 0.5634 2.0116 -1.3891 O.3 1 LIG1 -0.3429
> 17 O6 1.1223 -0.1529 -0.1877 O.3 1 LIG1 0.0575
> 18 P2 0.0541 -1.2893 -0.5527 P.3 1 LIG1 0.5624
> 19 O7 -1.1823 -1.2052 0.2607 O.3 1 LIG1 -0.3429
> 20 O8 0.6340 -2.6390 -0.3765 O.2 1 LIG1 -0.3429
> 21 O9 -0.2208 -1.0077 -2.1109 O.3 1 LIG1 -0.1602
> 22 O10 -2.0844 -2.0838 -4.0533 O.3 1 LIG1 -0.3483
> 23 C9 -1.7580 -0.6726 -3.9721 C.3 1 LIG1 0.1165
> 24 C10 -1.4291 -0.3206 -2.5098 C.3 1 LIG1 0.1276
> 25 N3 -5.5165 -1.9977 -1.1853 N.2 1 LIG1 -0.2341
> 26 C11 -5.3009 -1.7637 -2.4944 C.2 1 LIG1 0.0912
> 27 N4 -4.1259 -2.3733 -2.8716 N.3 1 LIG1 -0.2445
> 28 C12 -3.5825 -3.0679 -1.8327 C.2 1 LIG1 0.1583
> 29 C13 -4.4622 -2.7976 -0.7674 C.2 1 LIG1 0.1418
> 30 N5 -2.5159 -3.8010 -1.6563 N.2 1 LIG1 -0.2186
> 31 C14 -2.2518 -4.3018 -0.4707 C.2 1 LIG1 0.1192
> 32 N6 -3.0604 -4.0697 0.5431 N.2 1 LIG1 -0.2228
> 33 C15 -4.1365 -3.3442 0.4336 C.2 1 LIG1 0.1340
> 34 N7 -4.8438 -3.2010 1.5627 N.3 1 LIG1 -0.2849
> 35 C16 -2.1891 4.7099 1.7524 C.3 1 LIG1 0.1128
> 36 C17 -1.4568 6.0605 1.7533 C.3 1 LIG1 0.1256
> 37 C18 -0.3444 5.8071 0.7094 C.3 1 LIG1 0.1560
> 38 C19 -3.0362 0.0509 -4.4501 C.3 1 LIG1 0.1128
> 39 C20 -3.9053 -1.0632 -5.0633 C.3 1 LIG1 0.1257
> 40 C21 -3.5098 -2.2874 -4.2107 C.3 1 LIG1 0.1588
> 41 O11 -2.9991 4.5200 2.9209 O.3 1 LIG1 -0.3874
> 42 O12 -0.8413 6.3227 3.0256 O.3 1 LIG1 -0.3858
> 43 O13 -3.5425 -1.3145 -6.4282 O.3 1 LIG1 -0.3858
> 44 O14 -2.7472 1.1126 -5.3700 O.3 1 LIG1 -0.3874
> 45 H1 -1.6809 5.8357 -4.4909 H 1 LIG1 0.0632
> 46 H2 0.3396 4.6461 -3.6934 H 1 LIG1 0.0636
> 47 H3 0.9656 4.7572 -1.2733 H 1 LIG1 0.0793
> 48 H4 -2.2796 7.2615 -0.4632 H 1 LIG1 0.0801
> 49 H5 -4.8503 8.7190 -2.4374 H 1 LIG1 0.1458
> 50 H6 -3.7587 8.2854 -1.1465 H 1 LIG1 0.1458
> 51 H7 -0.6981 3.4004 2.6380 H 1 LIG1 0.0660
> 52 H8 -1.5845 2.7299 -0.2407 H 1 LIG1 0.0645
> 53 H9 -2.3510 2.0430 1.2095 H 1 LIG1 0.0645
> 54 H10 -0.9095 -0.4615 -4.6296 H 1 LIG1 0.0660
> 55 H11 -1.2870 0.7565 -2.4090 H 1 LIG1 0.0645
> 56 H12 -2.2603 -0.6329 -1.8739 H 1 LIG1 0.0645
> 57 H13 -5.9324 -1.1833 -3.1491 H 1 LIG1 0.1018
> 58 H14 -1.3609 -4.8928 -0.3242 H 1 LIG1 0.1064
> 59 H15 -4.6910 -3.8437 2.3366 H 1 LIG1 0.1259
> 60 H16 -5.8375 -2.9879 1.5154 H 1 LIG1 0.1259
> 61 H17 -2.8150 4.6581 0.8568 H 1 LIG1 0.0659
> 62 H18 -2.1232 6.8857 1.5028 H 1 LIG1 0.0675
> 63 H19 0.5295 6.4594 0.8618 H 1 LIG1 0.0853
> 64 H20 -3.5627 0.4623 -3.5840 H 1 LIG1 0.0659
> 65 H21 -4.9700 -0.8302 -5.0011 H 1 LIG1 0.0675
> 66 H22 -3.6913 -3.2429 -4.7274 H 1 LIG1 0.0854
> 67 H23 -3.4491 3.6578 2.8683 H 1 LIG1 0.2107
> 68 H24 -0.3142 7.1392 2.9619 H 1 LIG1 0.2108
> 69 H25 -3.3167 -0.4612 -6.8446 H 1 LIG1 0.2108
> 70 H26 -3.5789 1.5634 -5.6077 H 1 LIG1 0.2107
> @<TRIPOS>BOND
> 1 1 45 1
> 2 1 2 ar
> 3 1 6 ar
> 4 2 46 1
> 5 2 3 ar
> 6 3 47 1
> 7 3 4 ar
> 8 4 5 ar
> 9 5 48 1
> 10 5 6 ar
> 11 6 7 1
> 12 7 9 am
> 13 7 8 2
> 14 9 50 1
> 15 9 49 1
> 16 10 11 1
> 17 10 37 1
> 18 11 35 1
> 19 11 51 1
> 20 11 12 1
> 21 12 53 1
> 22 12 52 1
> 23 12 13 1
> 24 13 14 1
> 25 14 17 1
> 26 14 16 1
> 27 14 15 1
> 28 17 18 1
> 29 18 21 1
> 30 18 20 1
> 31 18 19 1
> 32 22 40 1
> 33 22 23 1
> 34 23 24 1
> 35 23 54 1
> 36 23 38 1
> 37 24 21 1
> 38 24 56 1
> 39 24 55 1
> 40 25 29 ar
> 41 25 26 ar
> 42 26 57 1
> 43 26 27 ar
> 44 27 28 ar
> 45 28 30 ar
> 46 29 33 ar
> 47 29 28 ar
> 48 30 31 ar
> 49 31 58 1
> 50 31 32 ar
> 51 32 33 ar
> 52 33 34 1
> 53 34 60 1
> 54 34 59 1
> 55 35 36 1
> 56 35 61 1
> 57 35 41 1
> 58 36 37 1
> 59 36 62 1
> 60 36 42 1
> 61 37 4 1
> 62 37 63 1
> 63 38 64 1
> 64 38 44 1
> 65 38 39 1
> 66 39 65 1
> 67 39 43 1
> 68 39 40 1
> 69 40 27 1
> 70 40 66 1
> 71 41 67 1
> 72 42 68 1
> 73 43 69 1
> 74 44 70 1
> @<TRIPOS>SUBSTRUCTURE
> 1 LIG1 1 GROUP 1 LIG 1
> ============================================================================
>
> <NAD.mol2><NAD.png>
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