Petruzzelli R, Aureli G, Casale E, Nardini M, Rizzi M, Ascenzi P, Coletta M, De Sanctis G, Desideri A, Galtieri A
Dipartimento di Biologia, Università di Roma, Tor Vergata, Italy.
Biochem Mol Biol Int. 1993 Sep;31(1):19-24.
The primary structure of myoglobin from the loggerhead sea turtle (Caretta caretta) has been determined; the protein consists of 153 amino acid residues. The ferric loggerhead sea turtle myoglobin has been crystallized in a form suitable for X-ray structural investigations. The crystals were grown at pH 8.0, in 0.05 M tris/HCl buffer, using 3.2 M ammonium sulfate as precipitating agent, at 4 degrees C, and belong to the orthorhombic space group P2(1)2(1)2(1), with unit cell constants a = 37.2 A, b = 61.1 A, c = 75.2 A (one molecule, 17,000 M(r), in the asymmetric unit). A molecular replacement solution was found for the loggerhead sea turtle myoglobin crystals using sperm whale myoglobin structure as search model. The R-factor value, after molecular replacement, is 0.387, for the data in the 15-3.3 A resolution range. The results here reported are the basis for the first X-ray crystallographic investigation on a reptile myoglobin, and indicate a strong overall structural similarity between the loggerhead sea turtle and mammalian (i.e. sperm whale) myoglobins.
蠵龟（Caretta caretta）肌红蛋白的一级结构已被确定；该蛋白质由153个氨基酸残基组成。三价铁的蠵龟肌红蛋白已结晶成适合进行X射线结构研究的形式。晶体在pH 8.0、0.05 M三羟甲基氨基甲烷/盐酸缓冲液中、以3.2 M硫酸铵作为沉淀剂、在4℃下生长，属于正交晶系空间群P2(1)2(1)2(1)，晶胞常数a = 37.2 Å，b = 61.1 Å，c = 75.2 Å（不对称单位中有一个分子，相对分子质量为17,000）。以抹香鲸肌红蛋白结构作为搜索模型，找到了蠵龟肌红蛋白晶体的分子置换解。对于15 - 3.3 Å分辨率范围内的数据，分子置换后的R因子值为0.387。此处报道的结果是对爬行动物肌红蛋白进行首次X射线晶体学研究的基础，并表明蠵龟和哺乳动物（即抹香鲸）肌红蛋白在整体结构上有很强的相似性。
