Gasdaska J R, Law J H, Bender C J, Aisen P
Department of Biochemistry, University of Arizona, Tucson, USA.
J Inorg Biochem. 1996 Dec;64(4):247-58. doi: 10.1016/s0162-0134(96)00052-9.
The optical and electron paramagnetic resonance (EPR) spectroscopic properties of a transferrin from the cockroach Blaberus discoidalis have been investigated to determine the relation of this protein to vertebrate transferrins. Difference spectrophotometry substantiates the involvement of tyrosyl residues in iron binding, and confirms the specific binding of two equivalents of iron per molecule. The far-UV CD spectrum also indicates a secondary structure with marked similarity to those of vertebrate transferrins. EPR studies show a dependence of iron binding on (bi)carbonate, consistent with the absolute requirement of transferrins for a synergistic anion in binding iron. Continuous wave (CW) and pulsed EPR studies of the cupric complex of the protein implicate a histidyl nitrogen ligand in metal coordination, as in human transferrin. Additional studies establish that the pH-dependent release of iron is similar to that of human serum transferrin. The present data confirm cockroach transferrin as an authentic member of the transferrin superfamily, thereby suggesting an ancestral relationship of insect to vertebrate transferrins.
为了确定蟑螂（Discoidalis蜚蠊）转铁蛋白与脊椎动物转铁蛋白之间的关系，对其光学和电子顺磁共振（EPR）光谱性质进行了研究。差示分光光度法证实了酪氨酸残基参与铁结合，并确认了每个分子特异性结合两个当量的铁。远紫外圆二色光谱也表明其二级结构与脊椎动物转铁蛋白的二级结构有显著相似性。EPR研究表明铁结合对（双）碳酸盐有依赖性，这与转铁蛋白在结合铁时对协同阴离子的绝对需求一致。对该蛋白质铜配合物的连续波（CW）和脉冲EPR研究表明，与人类转铁蛋白一样，在金属配位中存在一个组氨酸氮配体。进一步的研究表明，铁的pH依赖性释放与人类血清转铁蛋白相似。目前的数据证实蟑螂转铁蛋白是转铁蛋白超家族的一个真正成员，从而表明昆虫与脊椎动物转铁蛋白之间存在祖先关系。
