45] Methoxycarbonyl-CoA disulfide: An active site=directed sulfhydryl reagent

Abstract

Publisher Summary This chapter discusses the preparation and effects of methoxycarbonyl-CoA disulfide. The relative ease with which protein sulfhydryl groups reacted with a variety of compounds has led to the preparation of a large number of sulfhydryl reagents. These reagents have been classified according to the groups that are delivered, including blocking and labeling groups, reporter groups, cross-linking groups, and afffinity-abeling groups. Methoxycarbonyl-CoA disulfide is prepared by the reaction of free CoA with methoxycarbonylsulfenyi chloride. The latter compound is prepared in a two-step synthesis starting with trichloromethanesulfenyl chloride. Trichloromethanesulfenyl chloride is added to 211 g of concentrated sulfuric acid and 18 g of water. The mixture is stirred at 45–50° in a well-vented hood until hydrogen chloride evolution ceases. The methyl group of methoxycarbonyl-CoA disulfide can be replaced with a variety of alkyl groups by substituting different alcohols for methanol in the reaction with chlorocarbonylsulfenyl chloride. Radiolabeled reagent can be prepared by using 3 H-labeled CoA. The reaction of methoxycarbonyl-CoA disulfide with choline acetyltransferase is also discussed.