Mercury Soak for Lysozyme.

J.W. Pflugrath JWP at
Thu Jan 16 10:04:47 EST 1997

>I was wondering if anyone knows of the best mercury salt to use to obtain a
>single sited mercury derivative of Hen Egg White Lysozyme in sodium chloride? 
>The original studies used PCMBS (para-chloromercuribenzene sulphonate) but gave
>no specific details.

9 years of derivatizing lysozyme in the Cold Spring Harbor Macromolecular
course shows that pCMBS is an OK derivative at best.  You can co-crystallize
pCMBS and lysozyme.  Use 2-20 mM (or whatever) pCMBS in your drop.  Crystals
grow in 1 to 24 hours.
In my experience soaking does not work as well.  Here are two questions:
1.  Does lysozyme have any free sulfhydryl groups?
2.  Where does pCMBS bind?


PS:  You might try K2OsO4 and K2PtCl4 in high [5 mM to saturation] 
     concentrations and longer times.  When you find something that works
     well, please let me know.

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