Molecules: You'd better learn to live with them.
Yesterday's entry on Dithiothreitol garnered one lone comment. Remarking on the smell. True enough; it's a thiol - where there's sulfur, there's often stink. There is a biologically compatible reducing agent that doesn't stink at all: tris(carboxyethyl)phosphine, or TCEP.
It's usually sold as the hydrochloride salt. Interestingly, phosphines almost always stink too, but TCEP is nonvolatile, since it's charged. It's oxidized to the phosphine oxide (which are often quite insoluble, but the charges save you again here):
I've never actually used TCEP, but I've had a bottle of it in the fridge for about a year now. Anyone have any experience with it?
Comments
I don't have any experience with it, but the link below says it's used for selectively reducing disulfides to thiols and lists some journal references.
http://www.soltecventures.com/New%20Product1.htm
Posted by: Chris Hawkins | April 25, 2007 12:44 AM
TCEP would be pretty useful for keeping thiols (say, on a protein) in their reduced state in order to modify them with a thiol reactive moiety (e.g. a fluorescent molecule; DTT is unusable because it would soak up the thiol-reactive molecule) however TCEP is really expensive last time I checked.
Posted by: Peter Stirling | April 25, 2007 12:46 AM
I use TCEP immobilized on styrene beads. It works well for reducing disulfides to thiols in proteins and peptides as Chris Hawkins mentioned. Plus, you can easily remove the TCEP beads by centrifugation.
Posted by: RC Fuson | April 25, 2007 9:07 AM
TCEP is great; I prescribe it to biologists with pesky disulfide problems; especially since the reduction is *irreversible*. Also it has a pretty phat nucleophilic mechanism of action so I can push some arrows and make the biologists look dumb.
Whitesides invented the stuff, I believe.
Posted by: darksyde | April 30, 2007 3:31 AM
I know TCEP only as Tri(carboxyethyle) phosphine oxide. I wrote my PhD thesis about it. It has (had?) a wide commercial use as flame retardant. It is relatively untoxic, but causes highly specific brain damages at elevated dose levels. Due to the volume used worldwide it was tested in the 90s by the NTP standard carcinogenicity bioassay. The result was: not carcinogenic in mice, not carcinogenic in female rats, carcinogenic in kidney of male rats. This means a high species-selectivity, high gender selectivity and high organ selectivity. Therefore the probability of a specific carcinogenicity mechanism, which is not relevant to humans is high.
I spent four years of my life on tests, designed to elucidate whether TCEP induced kidney tumors in male rats by a mechanism, which is not relevant to humans. Unfortunytely I was not successful. Therefore TCEP has to be classified as probably carcinogenic to humans.
Posted by: Joerg Herbst | June 2, 2007 8:43 AM