[ccp4bb] Mg++ binding to N7 of G

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From: rcoulombe {- at -} LAV {- dot -} BOEHRINGER-INGELHEIM {- dot -} COM rcoulombe {- at -} LAV {- dot -} BOEHRINGER-INGELHEIM {- dot -} COM
Date: 2008-04-02

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Subject: Re: Mg++ binding to N7 of G
From: William Scott wgscott {- at -} CHEMISTRY {- dot -} UCSC {- dot -} EDU
Date: 2008-04-02

Subject: Mg++ binding to N7 of G
From: "William G {- dot -} Scott" wgscott {- at -} CHEMISTRY {- dot -} UCSC {- dot -} EDU
Date: 2008-04-02

Howdie folks:

I've got what appears to be an inner-sphere interaction between Mg++
and the N7 of a G. The mode of binding is the same as what is observed
at this site for Mn++, confirmed with anomalous data. Our resolution
is 1.6 Å, so I am reasonably confident this is right. However, my
chemist's viewpoint is that Mg++ is too hard and N is too soft for
this to happen.

I looked in a database called http://merna.lbl.gov for Mg++ binding
sites, and a bunch pop up for inner-sphere N7 interactions with Mg++.
However, if I restrict the search to structures having 1.8 Å
resolution or better, the number goes to zero.

Since Mg++ has the same number of electrons as water and no useful
absorbance, it seems assigning them based on hydration geometry and
bond distances is the only hope.

Does anyone have anything more definitive I can refer to?

Thanks.

Bill Scott

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CCP4bb <-- 2008 <-- April 2008 <-- 02 April 2008

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Subject: Re: Mg++ binding to N7 of G
From: William Scott wgscott {- at -} CHEMISTRY {- dot -} UCSC {- dot -} EDU
Date: 2008-04-02