Mallya S K, Van Wart H E
Department of Chemistry, Florida State University, Tallahassee 32306.
J Biol Chem. 1989 Jan 25;264(3):1594-601.
The mechanism of inhibition of two forms of human neutrophil collagenase (HNC) by six Au(I) compounds, some of which are used as chrysotherapeutic agents, has been investigated. The two forms of enzyme studied are active and latent HNC, the latter of which is activated by p-chloromercuribenzoate (PCMB). The effects of PCMB and Zn(II), which are normally included in the assays, on the activity of both forms of HNC and on their inhibition by these Au(I) compounds have also been studied. Zn(II) stimulates the activity of both the active and PCMB-activated latent forms of HNC up to a concentration of 50-100 microM, after which it inhibits markedly. PCMB activates latent HNC up to a concentration of 100 microM followed by inhibition at higher concentrations. Active HNC is not stimulated at PCMB concentrations below 100 microM, but is inhibited at higher concentrations. The stimulatory effects of Zn(II) and PCMB on HNC and its inhibition by PCMB are all attributable to binding at distinct sites. The inhibition of both active and PCMB-activated latent HNC by the Au(I) compounds is noncompetitive and is reversed by Zn(II). The inhibition of both forms of HNC by SKF 80544 and SKF 36914, which do not contain thiol ligands, is weak to moderate and is not influenced by the PCMB concentration. In contrast, PCMB markedly enhances the inhibition by Myocrisin, Sanocrisin, and Solganol by complexing to their thiol ligands to facilitate release of the Au(I) atom for binding to HNC. Cd(II) and Cu(II) also inhibit HNC noncompetitively, and inhibition is also reversed by Zn(II). Collectively, these data indicate that latent HNC contains a heavy metal binding site distinct from the active site at which Au(I), Cd(II), and Cu(II) bind to cause noncompetitive inhibition. Occupancy of this site by Zn(II) is characterized by retention of activity.
研究了六种金（I）化合物对两种形式的人中性粒细胞胶原酶（HNC）的抑制机制，其中一些金（I）化合物用作金疗法药物。所研究的两种酶形式是活性HNC和潜伏性HNC，后者可被对氯汞苯甲酸（PCMB）激活。还研究了通常包含在测定中的PCMB和锌（II）对两种形式HNC活性及其被这些金（I）化合物抑制的影响。锌（II）刺激活性HNC和PCMB激活的潜伏性HNC的活性，直至浓度达到50 - 100微摩尔/升，此后显著抑制。PCMB激活潜伏性HNC直至浓度达到100微摩尔/升，在更高浓度下则产生抑制作用。在PCMB浓度低于100微摩尔/升时，活性HNC不受刺激，但在更高浓度下受到抑制。锌（II）和PCMB对HNC的刺激作用及其被PCMB的抑制作用均归因于在不同位点的结合。金（I）化合物对活性和PCMB激活的潜伏性HNC的抑制均为非竞争性，且可被锌（II）逆转。不含硫醇配体的SKF 80544和SKF 36914对两种形式HNC的抑制作用较弱至中等，且不受PCMB浓度影响。相比之下，PCMB通过与Myocrisin、Sanocrisin和Solganol的硫醇配体络合，显著增强了它们的抑制作用，从而促进金（I）原子释放以与HNC结合。镉（II）和铜（II）也非竞争性抑制HNC，且抑制作用也可被锌（II）逆转。总体而言，这些数据表明，潜伏性HNC含有一个与活性位点不同的重金属结合位点，金（I）、镉（II）和铜（II）在该位点结合导致非竞争性抑制。锌（II）占据该位点的特征是保留活性。
