Muscle sulfhydryl groups

The oxidants responsible for initiating LDL oxidation have been under intense investigation, and several possible mechanisms have been suggested. For example, Oj has been implicated as a major contributor to LDL oxidation mediated by macrophages and smooth muscle cells (H8). Here, O " is converted to H2O2 by SOD, which in turn is acted upon by a transition metal ion with the formation of HO. Another possible role for Cff is its reaction with NO to form ONOCT, which is capable of oxidizing lipids and sulfhydryl groups, even in the presence of plasma antioxidants (VI). Moreover, in vitro studies have shown that ONOCT can induce the formation of F2-isoprostanes, nonenzymatic products of the free radical-catalyzed oxidation of arachidonic acid (M13). 

The role of sulfhydryl groups in phosphorylase activity is not yet known. Modification with p-chloromercuribenzoate certainly causes loss of activity, but it is uncertain whether die sulfhydryl groups form a part of the active center, or are more important for the maintenance of the active conformation of the protein molecule. The second possibility seems the more likely, as p-chloromercuribenzoate causes rabbit-muscle phosphorylase to split up into subunits. Also, the inhibition by this reagent is not parallel to mercaptide formation, and adenosine 5 -phosphate (which causes changes in the conformation of the enzyme) protects against the inhibition. Unmodified sulfhydryl groups are believed to be important for the binding of adenosine 5 -phosphate. ... 

K26. Kress, L. F., Bono, V. H., Jr., and Noda, L., The sulfhydryl groups of rabbit muscle adenosine triphosphate-adenosine monophosphate phosphotransferase. Activity of enzyme treated with mercurials. J. Biol. Chem. 241, 2293-2300 (1966). 

Heat-Induced Changes of Sulfhydryl Groups of Muscle Foods... 

Antioxidative properties, sulfur compounds in foods, 4 Aqueous washing, role in heat-induced changes of sulfhydryl groups of muscle foods, 174,1751... 

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