Re: [ccp4bb] radiation damage question

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Subject: Re: protein degraded when setting xtal?
From: Kevin Jude kjude {- at -} BERKELEY {- dot -} EDU
Date: 2008-03-03

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Subject: Re: radiation damage question
From: Philippe DUMAS p {- dot -} dumas {- at -} IBMC {- dot -} U-STRASBG {- dot -} FR
Date: 2008-03-03

Yes indeed ! H2 is one product of H2O radiolysis by recombination of two H
radicals.
Whether or not the cleavage of iodine (quite efficient under X-rays) is a
factor increasing H2 production, I don't know.

Philippe Dumas
IBMC-CNRS, UPR9002
15, rue Rene Descartes 67084 Strasbourg cedex
tel: +33 (0)3 88 41 70 02
p.dumas@ibmc.u-strasbg.fr

-----Message d'origine-----
De : CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK]De la part de
Patrick Loll
Envoye : Monday, March 03, 2008 6:00 PM
A : CCP4BB@JISCMAIL.AC.UK
Objet : [ccp4bb] radiation damage question

Hi all,

I had an interesting experience, and wonder if others have seen similar
things.

I was collecting data from a crystal that contains an iodinated
macromolecule. After 2 days on a copper rotating anode, with the crystal at
100 K, we experienced a detector problem, so I put the crystal back into the
dewar; it was diffracting nicely when I took it off. For various reasons, I
didn't get back to this crystal until about 3 weeks later. When I put it
back on the goniostat, the mother liquor was milky white in appearance.
There were no ice rings, but alas the crystal only gave a few anemic spots
around the beamstop. Annealing didn't help, and I noticed that when I
blocked the cold stream, the milky white appearance didn't go away when the
sample thawed. I finally took the crystal off and looked at it under a
microscope, at which point I discovered that the milky white appearance was
due to the presence of bubbles in the mother liquor.

I seem to recall some talks on radiation damage in which people mention
the evolution of a gas (H2?).

So: Does this seem like a radiation damage phenomenon? And have others
seen this kind of delay in the manifestation of damage during storage at
liquid N2 temperatures?

Thanks,

Pat

--------------------------------------------------------------------------
-------------

Patrick J. Loll, Ph. D. (215) 762-7706

Professor FAX: (215) 762-4452

Department of Biochemistry & Molecular Biology

Director, Biochemistry Graduate Program

Drexel University College of Medicine

Room 10-102 New College Building

245 N. 15th St., Mailstop 497

Philadelphia, PA 19102-1192 USA

pat.loll@drexel.edu

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CCP4bb <-- 2008 <-- March 2008 <-- 03 March 2008

Previous message:
Subject: Re: protein degraded when setting xtal?
From: Kevin Jude kjude {- at -} BERKELEY {- dot -} EDU
Date: 2008-03-03

Next message:
Subject: Positions available in Australia
From: Margaret Bills margaret {- dot -} bills {- at -} MED {- dot -} MONASH {- dot -} EDU {- dot -} AU
Date: 2008-03-03