Sulfonate group isotopes

Muller and Payot (196S) established by the radioactive-isotope method that the methylthio group of bis(alkylamino)-2-methylthio-. -triazines is oxidised in plants first to the sulfoxy then to the sulfon group, which is then quickly hydrolysed to the inactive hydroxy derivative ... 

Substitution of one of the two oxygen atoms in the sulfonyl group by 0 leads to a chiral sulfonyl group. The first example of a sulfone whose optical activity is due to such isotopic substitution was reported by Stirling (77) as early as 1963. The oxidation of (+> benzyl p-tolyl sulfoxide 37 with 0-labeled peracetic acid was found to give (-)-benzyl p-tolyl [ 0 0] sulfone 138. The same chiral... 

For non-quantitative LC-MALDI applications, derivatization chemistry is not restricted to compounds which allow a convenient incorporation of heavy isotopes. For example for improved MS/MS detection sensitivity, tryptic peptides were labeled with sulfonated coumarin-tags at the N-termini after guanidylation of lysines (Pashkova et al. 2005). Despite reduced MS sensitivity for arginine-terminated peptides (in alpha cyano-4-hydroxycinnamic acid matrix), formation of y-ions was enhanced in MS/MS by the second mobile proton provided from the sulfonic acid group. For a SCX fraction from a E.coli hydrolysate 50% more peptides and 30% more proteins could be identified by multiplexed LC-MALDI MS and MS/MS after derivatization. 

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