Charles Raymond Degenhardt

Assignment of all four disulfide Bridges in echistatin

Echistatin is a 49-amino-acid protein fromEchis carinatus venom. It contains four disulfide bonds. Since the disulfide bonding is critical for biological activity, it is very important to assign the disulfide linkage in this protein. Echistatin was incubated in 250 mM oxalic acid at 100°C for 4 hr under nitrogen. Under these conditions, many overlapping disulfide-containing peptides were identified by ionspray mass spectrometry. Ionspray MS/MS data indicate that the four disulfide bonds are Cys 2–Cys 11, Cys 7–Cys 32, Cys 8–Cys 37, and Cys 20–Cys 39. To our knowledge, this is the first time all four disulfide bonds in echistatin have been assigned in one experiment without disulfide bond exchange. This approach, which combines oxalic acid hydrolysis and ionspray MS/MS, may be very useful for assigning disulfide bridges in other proteins from the disintegrin family.

Use of Tetraethyl Dimethylaminomethylenediphosphonate in the Synthesis of Benzothiophene-2-acetic Acid and Other Carboxylic Acids

Abstract In 1968 Gross and Costisella reported that certain substituted benzaldehydes could be converted to the corresponding arylacetic acids through the use of tetraethyl dimethylaminomethylenediphosphonate (1).1 Since that time, little synthetic attention has been given to this potentially useful reagent and the scope of its utility in transforming aldehydes into carboxylic acids containing one more carbon2 remains undefined.