Hockenhull-Johnson J D, Stern M S, Martin P, Dass C, Desiderio D M, Wittenberg J B, Vinogradov S N, Walz D A
Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan 48201.
J Protein Chem. 1991 Dec;10(6):609-22. doi: 10.1007/BF01025713.
The cytoplasmic hemoglobin II from the gill of the clam Lucina pectinata consists of 150 amino acid residues, has a calculated Mm of 17,476, including heme and an acetylated N-terminal residue. It retains the invariant residues Phe 44 at position CD1 and His 65 at the proximal position F8, as well as the highly conserved Trp 15 at position A12 and Pro 38 at position C2. The most likely candidate for the distal residue at position E7, based on the alignment with other globins, is Gln 65. However, optical and EPR spectroscopic studies of the ferri Hb II (Kraus, D. W., Wittenberg, J. B., Lu, J. F., and Peisach, J., J. Biol. Chem. 265, 16054-16059, 1990) have implicated a tyrosinate oxygen as the distal ligand. Modeling of the Lucina Hb II sequence, using the crystal structure of sperm whale aquometmyoglobin, showed that Tyr 30 substituting for the Leu located at position B10 can place its oxygen within 2.8 A of the water molecule occupying the distal ligand position. This structural alteration is facilitated by the coordinate mutation of the residue at position CD4, from Phe 46 in the sperm whale myoglobin sequence to Leu 47 in Lucina Hb II.
来自栉江珧鳃的细胞质血红蛋白II由150个氨基酸残基组成，计算所得的分子量为17,476，包括血红素和一个N端乙酰化残基。它保留了位于CD1位置的不变残基苯丙氨酸44、近端F8位置的组氨酸65，以及位于A12位置的高度保守的色氨酸15和位于C2位置的脯氨酸38。基于与其他球蛋白的比对，E7位置最可能的远端残基候选是谷氨酰胺65。然而，高铁血红蛋白II的光学和电子顺磁共振光谱研究（克劳斯，D. W.，维滕贝格，J. B.，卢，J. F.，和佩萨克，J.，《生物化学杂志》265，16054 - 16059，1990）表明酪氨酸氧是远端配体。利用抹香鲸高铁肌红蛋白的晶体结构对栉江珧血红蛋白II序列进行建模显示，取代位于B10位置的亮氨酸的酪氨酸30可使其氧原子处于距离占据远端配体位置的水分子2.8埃以内。栉江珧血红蛋白II中CD4位置的残基由抹香鲸肌红蛋白序列中的苯丙氨酸46协同突变为亮氨酸47，促进了这种结构改变。
