Molecular recognition of angiogenesis inhibitors fumagillin and ovalicin by methionine aminopeptidase 2
Molecular recognition of angiogenesis inhibitors fumagillin and ovalicin by methionine aminopeptidase 2
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DOI：
10.1073/pnas.95.26.15183
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发表时间：
1998-12-22
影响因子：
11.1
通讯作者：
Liu, JO
中科院分区：
文献类型：
--
作者：
Griffith, EC;Su, Z;Liu, JO
血管生成抑制剂是一类很有前途的治疗癌症和其他人类疾病的药物。烟曲菌素和卵黄素是一类结构相关的天然产物，通过阻断内皮细胞的增殖而有效地抑制血管生成。合成的烟曲菌素类似物TNP-470目前正在进行治疗多种癌症的临床试验，最近烟曲菌素和卵黄素的一个共同靶点被确定为2型甲硫氨酸氨基肽酶(Metap2)，这些天然产物与MetAP2共价结合，抑制其酶活性。这种结合的特异性因缺乏对密切相关的1型酶MetAP1的抑制而得到强调，这些抑制剂对MetAP2的高亲和力和特异性的分子基础仍未被发现。为了确定参与这种相互作用的抑制剂和MetAP2的结构元素，我们合成了伏马西林类似物，其中每个潜在的活性环氧化物被单独或组合移除，我们发现伏马西林中的环氧化物参与了MetAP2的共价修饰，而侧链环氧化物是必不可少的。通过使用荧光素标记的烟曲霉素类似物，确定MetAP2中的His-231是被烟曲霉青霉素共价修饰的残基，His-231的定点突变证明了其对MetAP2催化活性的重要性，并证实了同样的残基是被烟美西林共价修饰的，这些结果与最近的结构研究相一致，表明烟美西林和卵黄素通过不可逆地阻断活性部位而抑制MetAP2。
Angiogenesis inhibitors are a novel class of promising therapeutic agents for treating cancer and other human diseases. Fumagillin and ovalicin compose a class of structurally related natural products that potently inhibit angiogenesis by blocking endothelial cell proliferation, A synthetic analog of fumagillin, TNP-470, is currently undergoing clinical trials for treatment of a variety of cancers, A common target for fumagillin and ovalicin recently was identified as the type 2 methionine aminopeptidase (MetAP2), These natural products bind MetAP2 covalently, inhibiting its enzymatic activity. The specificity of this binding is underscored by the lack of inhibition of the closely related type 1 enzyme, MetAP1, The molecular basis of the high affinity and specificity of these inhibitors for MetAP2 has remained undiscovered. To determine the structural elements of these inhibitors and MetAP2 that are involved in this interaction, we synthesized fumagillin analogs in which each of the potentially reactive epoxide groups was removed either individually or in combination, We found that the ring epoxide in fumagillin is involved in the covalent modification of MetAP2, whereas the side chain epoxide group is dispensable. By using a fumagillin analog tagged with fluorescein, His-231 in MetAP2 was identified as the residue that is covalently modified by fumagillin, Site-directed mutagenesis of His-231 demonstrated its importance for the catalytic activity of MetAP2 and confirmed that the same residue is covalently modified by fumagillin, These results, in agreement with a recent structural study, suggest that fumagillin and ovalicin inhibit MetAP2 by irreversible blockage of the active site.