Methane thiosulfonate

In soft cheeses, such as Brie, Camembert, and Limburger, the following sulfur compounds were implicated 3-(methylthio)propanol, MT, DMS, DMDS, DMTS, dimethyl tetrasulfide, methyl ethyl disulfide, diethyl disulfide, 2,4-dithiapentane, 3-methylthio-2,4-dithiapentane, methional, 2,4,5-trithiahex-ane, 1,1-fe-methylmercaptodisulfide, methyl thioacetate (=methanethiol acetate), benzothiazole, methylthiobenzothiazole, methyl ethyl sulfonate, methyl methane thiosulfonate, thiophene 2-aldehyde, and H2S.34 Many of these were only present in small amounts Limburger cheese was notable for 13.2% of DMDS, 0.5% of methyl thioacetate, and 0.8% of DMTS. 

To increase the enantioselectivity of these myoglobin metalloenzymes, Lu and co-workers have successfully utilized a covalent linkage approach [62], In an earlier attempt a Mn(III)-salen complex was incorporated into apo-myoglobin by mutating residue 103 to cysteine, followed by modification with a methane thiosulfonate derivative of Mn(III)(salen) (Figure 5.16). This catalyst showed sulfoxidation activity however, the ee was only 12 %. As such a low ee might be a result of the ability of the bound ligand to exist in multiple conformations within the protein cavity, it was hypothesized that the rotational freedom of the salen complex could be limited if it was anchored at... 

Corina and coworkers65 gave the El mass spectra of two fluorinated ethyl methane-thiosulfonates (95 and 96), which showed distinct molecular ions and preferential S—S bond cleavage, in analogy with unsubstituted 93a. However, the extent of fluorine substitution affected the site of charge retention, so that base peaks at m/z 78, [CH2FCHS]+, and m/z 79, [MeS02]+, were found for 95 and 96, respectively. 

Bloxham, D. P., and Cooper, G. K. (1982) Formation of a polymethylene bis(disulfide) intersubunit cross-link between cys-281 residues in rabbit muscle glyceraldehyde-3-phosphate dehydrogenase using octamethylene bis(methane[ ]thiosulfonate). Biochemistry 21, 1807. 

Analysis of the surface oxidation products using either TA or GC/MS indicated that the predominant product of surface oxidation is DMDS. In the case of the coconut shell based carbon with veiy small pores present, S208, the traces of methyl methane thiosulfonate (CzHsOaSa) were detected. It can be the product of the reaction of DMD with oxygen ... 

Fig. 1. Three representative spin-labeling reactions. Reaction I shows the maleimide spin label which is specific for -SH and -NH2 groups. Reaction II shows the methane thiosulfonate spin label which is specific for -SH. Reaction III involves the succinimide spin label which attaches to -NH2.

Fig. 4. Stereo drawing of a spin-labeled 3K-8 peptide. The peptide is in the geometry of a 310 helix. The nitroxide label, which is pointing out on the left-hand side of the peptide, is the methane thiosulfonate spin label. This label attaches with sufficient rigidity to report the expected value of Tg for the peptide.

Eighteen site-directed mutants of bacteriorhodopsin were prepared, each with a single X cysteine (Cys) substitution sequentially placed from positions 125 to 142. These residues are in a region of the protein which starts near the end of one transmembrane helix, passes through an interhelical loop, and then stretches well into the next helical segment (Fig. 7). The mutants were reacted with methane thiosulfonate spin label, which specifically attaches to the Cys (Fig. 1). Extreme care was taken to characterize the folding and functionality of each spin-labeled mutant to ensure that there was little measurable perturbation from the... 

---