锥虫的83千道尔顿热休克蛋白是有效的肽刺激ATP酶。
83-kilodalton heat shock proteins of trypanosomes are potent peptide-stimulated ATPases.
作者信息
Nadeau K, Sullivan M A, Bradley M, Engman D M, Walsh C T
机构信息
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115.
出版信息
Protein Sci. 1992 Aug;1(8):970-9. doi: 10.1002/pro.5560010802.
A Crithidia fasciculata 83-kDa protein purified during a separate study of C. fasciculata trypanothione synthetase was shown to have ATPase activity and to belong to the hsp90 family of stress proteins. Because no ATPase activity has previously been reported for the hsp90 class, ATP utilization by C. fasciculata hsp83 was characterized: this hsp83 has an ATPase kcat of 150 min-1 and a Km of 60 microM, whereas the homologous mammalian hsp90 binds ATP but has no ATPase activity. Crithidia fasciculata hsp83 undergoes autophosphorylation on serine and threonine at a rate constant of 3.3 x 10(-3) min-1. Similar analysis was performed on recombinant Trypanosoma cruzi hsp83, and comparable ATPase parameters were obtained (kcat = 100 min-1, Km = 80 microM, kautophosphorylation = 6.3 x 10(-3) min-1). The phosphoenzyme is neither on the ATPase hydrolytic pathway nor does it affect ATPase catalytic efficiency. Both C. fasciculata and T. cruzi hsp83 show up to fivefold stimulation of ATPase activity by peptides of 6-24 amino acids.
在对 fasciculata 锥虫硫醇合成酶的另一项研究中纯化得到的一种 Crithidia fasciculata 83-kDa 蛋白，被证明具有 ATP 酶活性，且属于应激蛋白的 hsp90 家族。由于此前尚未报道 hsp90 类蛋白具有 ATP 酶活性，因此对 Crithidia fasciculata hsp83 的 ATP 利用情况进行了表征：这种 hsp83 的 ATP 酶催化常数 kcat 为 150 min-1，米氏常数 Km 为 60 μM，而同源的哺乳动物 hsp90 结合 ATP 但无 ATP 酶活性。Crithidia fasciculata hsp83 在丝氨酸和苏氨酸上进行自身磷酸化，速率常数为 3.3×10(-3) min-1。对重组克氏锥虫 hsp83 进行了类似分析，得到了可比的 ATP 酶参数（kcat = 100 min-1，Km = 80 μM，自身磷酸化速率 kautophosphorylation = 6.3×10(-3) min-1）。磷酸化酶既不在 ATP 酶水解途径上，也不影响 ATP 酶催化效率。Crithidia fasciculata 和克氏锥虫的 hsp83 对 6 - 24 个氨基酸的肽段均表现出高达五倍的 ATP 酶活性刺激。
Zotero 插件