Glutathione-maleimide

Showdomycin inhibits synthesis of nucleic acid. Thiols, such as cysteine and glutathione (among other compounds), reverse this inhibition, and it is considered that the interaction of the maleimide moiety with sulfhydryl groups within the cell or in the membrane may be responsible for the selective inhibition of enzymes by show-... 

Moreover, we combined the proposed CL reaction with HPLC for the determination of biological thiols such as cysteine, homocysteine, A-acetylcysteine and glutathione by using A-[4-(dimethylamino-2-benzofuranyl)phenyl]maleimide (DBPM) as a chemiluminescent labeling reagent. The labeled thiols were separated and detected by CL after mixing with just the aryloxalate. Finally, the method was applied to the determination of biological thiols in human serum. 

N-(1-Pyrenyl)maleimide and N-(7-dimethylamino-4-methylcoumarinyhmaleimide [446,447] have been used for the determination of N-acetylcysteine. Cysteine and glutathione have been determined using N-(9-acridinyl)-maleimide [448,449], and D-penicillamine with N-[(p-2-benzoxazolyl)phenyl]maleimide [450]. More recently, N-[4-(6-dimethylamino-2-benzofuranyl)phenyl]maleimide (DBPM) was synthesized and used for the rapid chromatographic determination of some natural thiols [451, 452]. 

Oxidation alone of pyridine nucleotides is not sufficient to induce Ca release. In the presence of ATP, the hydroperoxide-induced pyridine nucleotide oxidation is even accelerated, yet pyridine nucleotide hydrolysis and Ca release are inhibited [11]. Similar observations were made during the menadione-induced Ca release [10]. When liver mitochondria are treated with N-ethyl maleimide to lower intramitochondrial glutathione, both oxidation of pyridine nucleotides and Ca " release are inhibited (S. Baumhuter, C. Richter, unpubl.). Finally, both pyridine nucleotide hydrolysis and Ca release show the same sigmoidal dependence on the mitochondrial Ca load [15]. Thus, there is clear, albeit circumstantial, evidence that pyridine nucleotide hydrolysis and Ca " release are functionally related. The link between the two processes may be protein ADP-ribosylation. 

---