Leukotriene A4 hydrolase. Inhibition by bestatin and intrinsic aminopeptidase activity establish its functional resemblance to metallohydrolase enzymes.
Leukotriene A4 hydrolase. Inhibition by bestatin and intrinsic aminopeptidase activity establish its functional resemblance to metallohydrolase enzymes.
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DOI：
10.1016/s0021-9258(18)52303-6
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发表时间：
1991-01
期刊：
影响因子：
--
通讯作者：
L. Orning;Gwen G. Krivi;Frank A. Fitzpatrick
中科院分区：
文献类型：
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作者：
L. Orning;Gwen G. Krivi;Frank A. Fitzpatrick
Bestatin是一种氨肽酶抑制剂，也是一种有效的白三烯（LT）A4水解酶抑制剂。对分离的酶，其作用是立即和可逆的Ki = 201 +/- 95 mM。与红细胞，它抑制LTB 4形成大于90%在10分钟内;与中性粒细胞，它抑制LTB 4形成仅10%，在同一时期，在2小时内增加到40%。Bestatin选择性地抑制LTA 4水解酶;中性粒细胞裂解物中的5-脂氧合酶和15-脂氧合酶活性均不受影响。纯化的LTA 4水解酶表现出内在的氨肽酶活性，水解L-赖氨酸-对硝基苯胺和L-亮氨酸-β-萘酰胺，表观Km分别为156 μ M和70 μ M，Vmax分别为50和215 nmol/min/mg。LTA 4和bestatin均抑制LTA 4水解酶的内在氨肽酶活性，表观Ki值分别为5.3 μ M和172 nM。其他金属水解酶抑制剂测试没有降低LTA 4水解酶/氨肽酶活性，有一个例外;卡托普利，血管紧张素转化酶的抑制剂，是有效的bestatin。结果表明LTA 4水解酶和某些金属水解酶之间的功能相似性，与它们假定的Zn 2（+）结合位点的分子相似性一致。LTA 4水解酶的可逆的、化学稳定的抑制剂的可用性可能有助于研究LTB 4在炎症中的作用，特别是称为跨细胞生物合成的过程。
Bestatin, an inhibitor of aminopeptidases, was also a potent inhibitor of leukotriene (LT) A4 hydrolase. On isolated enzyme its effects were immediate and reversible with a Ki = 201 +/- 95 mM. With erythrocytes it inhibited LTB4 formation greater than 90% within 10 min; with neutrophils it inhibited LTB4 formation by only 10% during the same period, increasing to 40% in 2 h. Bestatin inhibited LTA4 hydrolase selectively; neither 5-lipoxygenase nor 15-lipoxygenase activity in neutrophil lysates was affected. Purified LTA4 hydrolase exhibited an intrinsic aminopeptidase activity, hydrolyzing L-lysine-p-nitroanilide and L-leucine-beta-naphthylamide with apparent Km = 156 microM and 70 microM and Vmax = 50 and 215 nmol/min/mg, respectively. Both LTA4 and bestatin suppressed the intrinsic aminopeptidase activity of LTA4 hydrolase with apparent Ki values of 5.3 microM and 172 nM, respectively. Other metallohydrolase inhibitors tested did not reduce LTA4 hydrolase/aminopeptidase activity, with one exception; captopril, an inhibitor of angiotensin-converting enzyme, was as effective as bestatin. The results demonstrate a functional resemblance between LTA4 hydrolase and certain metallohydrolases, consistent with a molecular resemblance at their putative Zn2(+)-binding sites. The availability of a reversible, chemically stable inhibitor of LTA4 hydrolase may facilitate investigations on the role of LTB4 in inflammation, particularly the process termed transcellular biosynthesis.