Dear Tina,
my guess would be minor oxidation of the cysteine. The green positive
difference density suggests a bound atom in three different positions; this
could however just be the first atom of something bigger like
beta-mercaptoethanol, with the rest of that molecule too disordered to see.
2cystein.jpeg looks just like oxidation of cysteine to
S-hydroxy-cysteine (a.k.a. cysteine sulfenic acid). I have seen this
repeatedly in one of my structures (E. coli aminopeptidase P, see 1WL9
for an example). We discuss this a bit in Graham et al (2005)
Biochemistry 44: 13820-36 - see Figure 2
:* Monday, August 13, 2007 9:59 PM
*To:* CCP4BB@JISCMAIL.AC.UK
*Subject:* [ccp4bb] extra density on Cysteine
Dear all,
I am refining a 2.0A structure. I found that there were some extra
density on two cysteines, even though I have added 5mM BME in the
protein buffer.
I am wondering whether the
cp4bb] extra density on Cysteine
Dear all,
I am refining a 2.0A structure. I found that there were some extra density
on two cysteines, even though I have added 5mM BME in the protein buffer.
I am wondering whether the first one (Cys292) is a bme and the second one is
an oxidized cysteine
