Re: [AMBER] lipid params

From: Benjamin Madej <bmadej.ucsd.edu>
Date: Mon, 16 Jul 2012 14:54:29 -0700

1. See my previous email. DMPC =
1,2-Dimyristoyl-sn-Glycero-3-Phosphocholine. Myristoyl was not included in
Lipid11, but it'll probably be added in the future.

2. I made a mistake in the previous email and let me clarify: I meant to say
sn-2 carbon is the stereogenic center of the phospholipid (same carbon as in
your figure). I believe that this carbon is usually in the R configuration
according to the textbook I previously referenced. I haven't looked at other
sources in detail, though. And, I don't know the structural details of the
simulations in that paper.

Ben Madej
Walker Molecular Dynamics Lab

2) *** Prof./Dr. Benjamin,

>>I assume you're talking about the stereogenic center of the
>>phospholipid


To avoid further confusion, I have attached the image (source: JCC,29(1),
24-37). I was discussing about the boxed carbon C3 (it is DMPC molecule). No
other chiral centre I can see (please correct me).
It should be 'R' as what CHARMM GUI provides us but 'S' was used in
mentioned paper. Is there any special reason to use S and its validation
with GAFF?


3) *** Prof. Junmie Wang (gaff developer), Gould,

>>The P4 is correct, the phosphorous has three different substituents
attached, the two oxygens which are >> attached to the phosphorous are
equivalent.

I am confused about the term "equivalent" and new for me. If it is the case
then atom type like p5 (which I think was suitable instead of p4) will loose
its significance to exist even!. lets say what gaff provides "p5 Phosphate
with four connected atoms, such as O=P(OH)3". here also one can see three
OHs being "equivalent", then can I say that atom type p2 is also OK or
something like that.



thanks and regards,


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Received on Mon Jul 16 2012 - 15:00:03 PDT
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