CHARACTERIZATION OF THE INHIBITION OF P4501A2 BY FURAFYLLINE
CHARACTERIZATION OF THE INHIBITION OF P4501A2 BY FURAFYLLINE
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DOI：
10.3109/00498259409043254
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发表时间：
1994-06-01
期刊：
影响因子：
1.8
通讯作者：
CHENERY, RJ
中科院分区：
文献类型：
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作者：
CLARKE, SE;AYRTON, AD;CHENERY, RJ
1. 呋喃茶碱对人肝微粒体系统中1a2相关活性的抑制作用被表征。这种抑制是时间和NADPH依赖性的。测定了人肝微粒体的动力学常数；测定了3 μ M的失活K-i，最大速率常数为0.27 min（-1）。这种失活过程因存在1A2底物而延迟，在完全抑制后，可以通过在孵育混合物中添加新鲜微粒体来恢复1A2的活性。这些结果与呋喃茶碱是1A2.3的自杀底物一致。在加入底物开始反应之前，用10 μ M呋喃茶碱在NADPH存在下将微粒体预孵育10分钟，可显著抑制1A2活性。该方案对10种人类P450活性进行了特异性测试。与1A1、2A6、2B6、2C9（/8）、2C19、2D6、2E1、3A4（/5）和A相关的活性未被显著抑制。在这些条件下，呋喃茶碱可以诊断1A2参与p450依赖的氧化反应。
1. Furafylline inhibition of 1A2-related activity in human liver microsomal systems was characterized. This inhibition was time and NADPH dependent. The kinetic constants were measured in human liver microsomes; a K-i of inactivation of 3 mu M with a maximum rate constant of 0.27 min(-1) were determined.2. This inactivation process was retarded by the presence of a 1A2 substrate and after complete inhibition was achieved, 1A2 activity could be restored by the addition of fresh microsomes to the incubation mixture. These results are consistent with furafylline being a suicide substrate for 1A2.3. Preincubating microsomes for 10 min with 10 mu M furafylline in the presence of NADPH, prior to the initiation of the reaction by the addition of substrate, caused marked inhibition of 1A2 activity. This protocol was tested for specificity against 10 human P450 activities. The activities associated with 1A1, 2A6, 2B6, 2C9(/8), 2C19, 2D6, 2E1, 3A4(/5) and A were not significantly inhibited.4. Using these conditions furafylline call be diagnostic of 1A2 involvement in a P450-dependent oxidative reaction.