Handel M L, Watts C K, Sivertsen S, Day R O, Sutherland R L
Cancer Biology Division, Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, New South Wales, Australia.
Mol Pharmacol. 1996 Sep;50(3):501-5.
D-Penicillamine (beta, beta-dimethyl cysteine) is an antirheumatic thiol drug with a poorly understood mechanism of action. On the basis that gold(I) thiolates and D-penicillamine are both capable of forming stable bonds with endogenous thiols, we sought a common target of action. Cysteine residues in the basic DNA binding domains of Jun and Fos, members of the activator protein-1 (AP-1) transcription factor family, have been identified as likely targets for the therapeutic action of antirheumatic gold(I) thiolates. The current study demonstrates that AP-1 DNA binding is inhibited by D-penicillamine in the presence of Fenton reagents (Fe2+/EDTA and H2O2) but not with either agent alone. The effect is biphasic, with maximum inhibition in the concentration range of approximately 100-250 microM. Cysteine has qualitatively similar properties, although the effect is less pronounced. In contrast, glutathione and thiomalate do not inhibit AP-1 DNA binding, even in the presence of Fenton reagents. Mutant proteins were used to identify the cysteine residues within the DNA binding domains of Jun and Fos that are essential for the inhibitory action of D-penicillamine. The results suggest that D-penicillamine is distinguished from other thiols by its formation of sulfur-containing radicals capable of inhibiting AP-1 DNA binding by a mechanism involving the cysteine residues of Jun and Fos.
D-青霉胺（β，β-二甲基半胱氨酸）是一种抗风湿硫醇类药物，其作用机制尚不清楚。基于金（I）硫醇盐和D-青霉胺都能够与内源性硫醇形成稳定键，我们寻找了一个共同的作用靶点。活化蛋白-1（AP-1）转录因子家族成员Jun和Fos的碱性DNA结合域中的半胱氨酸残基已被确定为抗风湿金（I）硫醇盐治疗作用的可能靶点。当前研究表明，在芬顿试剂（Fe2+/EDTA和H2O2）存在的情况下，D-青霉胺可抑制AP-1与DNA的结合，但单独使用这两种试剂时则无此作用。这种作用是双相的，在约100-250 microM的浓度范围内抑制作用最大。半胱氨酸具有定性相似的性质，尽管作用不太明显。相比之下，即使在芬顿试剂存在的情况下，谷胱甘肽和硫代苹果酸也不会抑制AP-1与DNA的结合。使用突变蛋白来鉴定Jun和Fos的DNA结合域中对于D-青霉胺抑制作用至关重要的半胱氨酸残基。结果表明，D-青霉胺与其他硫醇的区别在于其形成含硫自由基，该自由基能够通过涉及Jun和Fos半胱氨酸残基的机制抑制AP-1与DNA的结合。
