L-(+)-Cysteine → N-Acetyl-L-Cysteine

Participants

Reaction Steps

Incubation of 100 μM Cys and 50 μM GlcN-Ins with 1 mM ATP in phosphate buffer, pH 7.5, containing 1 DTT after addition of cell extract supernatant resulted in an increase in Cys-GlcN-Ins from <0.2 to 26 μM over 60 min while the MSH content declined from 15 to 13 μM, corresponding to the MSH content present in the undialyzed cell extract. A parallel experiment with 100 μM AcCys in place of Cys resulted in an increase from <0.2 to 20 μM Cys-GlcN-Ins, and no change in MSH content (15 μM); however, marked conversion of AcCys to Cys had occurred by 60 min ([Cys]/[AcCys]˜3). If the MSH had increased by as much as 2 μM (10% of the change in Cys-GlcN-Ins) the change would have been detected and this experiment therefore established that conversion of Cys to Cys-GlcN-Ins is at least an order of magnitude faster than conversion of AcCys to MSH under these conditions.

Provenance & Evidence