My best guess would be acetylation/propionylation with the oxygen pointing into the top small green density.
cheers
Ajit B.
----- Original Message -----
From: Christian Biertuempfel <[log in to unmask]>
Date: Tuesday, June 29, 2010 2:54 pm
Subject: [ccp4bb] density quiz
To: [log in to unmask]
> Dear all,
> Does anyone have an idea what this density at a lysine residue could be?
> The structure is a protein-DNA complex and I suspect that something
> left-over from the DNA synthesis reacted with the amino group even
> though the DNA substrate was purified.
>
> christian
>
> p.s. The protein has seen the following substances during purification
> and crystallization: Leupeptin, Pepstatin, AEBSF, MES, Tris, HEPES, DTT,
> EDTA, imidazole, glycerol, PEG 2K-MME, Mg2+, Na+, K+, Ca2+, Cl-.
>
>
> _______________________________________________________________________
>
> Dr. Christian Biertümpfel
> Laboratory of Molecular Biology
>
> NIDDK/National Institutes of Health phone: +1 301 402 4647
> 9000 Rockville Pike, Bldg. 5, Rm. B1-03 fax: +1 301 496 0201
> Bethesda, MD 20892-0580
> USA
> _______________________________________________________________________
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