******************************************************************************* From: "Peter M. van Galen" Subject: GC/MS determination of cysteine-derivatives Date: Thu, 01 Aug 1996 16:25:32 +0200 Organization: KUN Hello, We would like to contact people who have experience with the determination of cysteine derivatives in general, either by direct inlet MS or GC/MS. Questions are: How to derivatise cysteines to as apolar as possible compounds. We've tried actylation but with little success. Has anyone suggestions on the ionization technique to be applied, we've tried both EI and CI with and without GC, but didn't see any molecular-ion information. Has anyone experience in the determination of sulfinamide, sulfenamide or cysteinylnitropyrene at low levels of concentretion. Any hints or literature references would be very welcome at: Y.vanBekkum@toxi.kun.nl and pvang@sci.kun.nl with regards, |--------------------------------------------------------------------| |Peter M. van Galen | Mass Spectrometry | Toernooiveld 1 | | | Organic Chemistry Dept.| 6525 ED Nijmegen | | | Nijmegen University | Netherlands | |-------------------------------------------------------------------- |******************************************************************************* From: lippy@UVic.CA Date: Thu, 08 Aug 1996 16:52:38 GMT Subject: Re: GC/MS determination of cysteine-derivatives Organization: University of Victoria I can suggest one modification that may work for you. 4-vinylpyridine is commonly used in protein chemistry for cysteine modification. It's an excellent reagent and pyridethyl cysteine is pretty damn apolar. I've had no end of solubility headaches with my proteins after this treatment, but it might be just the thing for you. I've got two references to help you along: J. Cavins and M. Friedman (1979), Anal. Biochem. (35):489-493 and V. Wu and M. Friedman (1971), Canadian J. of Biochem. (49):1042-1049 Best of luck, Dustin Lippert