STUDIES ON TISSUE TRANSGLUTAMINASES - INTERACTION OF ERYTHROCYTE TYPE-2 TRANSGLUTAMINASE WITH GTP
STUDIES ON TISSUE TRANSGLUTAMINASES - INTERACTION OF ERYTHROCYTE TYPE-2 TRANSGLUTAMINASE WITH GTP
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DOI：
10.1042/bj2910037
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发表时间：
1993-04-01
影响因子：
4.1
通讯作者：
SIGNORINI, M
中科院分区：
文献类型：
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作者：
BERGAMINI, CM;SIGNORINI, M
Ca 2+和GTP是2型转氨酶的主要调节剂。为了研究酶与GTP的相互作用，我们采用高碘酸氧化GTP作为亲和标记探针。二醛GTP结合不可逆的2型转氨酶在一个时间依赖性的方式与1：1的化学计量在完全修改。反应在不存在氰基硼氢化物的情况下发生，但在存在氰基硼氢化物的情况下更快。天然GTP阻止二醛GTP的掺入，并且Ca 2+显著减慢反应速率。修饰后的酶对Ca ~（2+）的敏感性降低，呈S形饱和曲线。我们的结论是，2型转氨酶有一个单一的GTP结合位点，修饰的二醛GTP模仿核苷酸结合酶。
Ca2+ and GTP are the main modulators of type-2 transglutaminases. To study the interaction of the enzyme with GTP, we have employed periodate-oxidized GTP as an affinity-label probe. Dialdehyde GTP bound irreversibly to type-2 transglutaminase in a time-dependent way with 1:1 stoichiometry at complete modification. The reaction took place in the absence, but was more rapid in the presence, of cyanoborohydride. Native GTP prevented incorporation of dialdehyde GTP, and Ca2+ significantly slowed down the reaction rate. The modified enzyme displayed decreased sensitivity to Ca2+, with a sigmoid saturation curve. We conclude that type-2 transglutaminase has a single GTP-binding site, the modification of which by dialdehyde GTP mimics nucleotide binding to the enzyme.