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Lawrence McIntosh mcintosh at OTTER.BIOCHEM.UBC.CA
Tue Aug 3 19:45:52 EST 1999

Hi - I am not sure if it is a LBHB, but certainly is a strong
h-bond. Other examples of Asp/Glu-Asp/Glu pairs can be found
in HIV protease and several so-called acidic xylanases (e.g. 1xyn).

The interesting question relates to the pH and ionization state
of the Asp's. They are likely either both neutral or one is neutral
and one charged. Can you run an NMR spectrum to look for a downfield
shifted proton resonance (e.g. 18 ppm)?

I am interested in this for our studies of xylanases, so let
me know of any other replies.



Lawrence McIntosh
2146 Health Sciences Mall
Departments of Biochemistry and Chemistry
University of British Columbia
Vancouver, BC, Canada V6T 1Z3

mcintosh at otter.biochem.ubc.ca
ph:  (604) 822-3341
fax: (604) 822-5227


On 3 Aug 1999, Matthew Meyer wrote:

> Can anyone out there tell me whether it is reasonable to suspect a low
> barrier hydrogen bond (O--H--O)
> between 2 Asp residues' OD1s?  I have a 1.7A structure in which I have
> manually separated them to VDW radii, and upon minimization refinement
> w/ CNS they consistently move back to a 2.65A distance.
> Thanks in advance
> p.s. sorry if this is inappropriate for the O listserv
> --
> Matthew G. Meyer
> Penn State University
> Dept. Biochemistry & Mol. Biology
> 6 Althouse/154 N. Frear
> University Park, PA 16802
> (814)865-8383/863-4904
> mgm10 at psu.edu

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