Lee W Y, Brune D C, LoBrutto R, Blankenship R E
Departments of Chemistry and Biochemistry, Arizona State University, Temple 85287-1604, USA.
Arch Biochem Biophys. 1995 Apr 1;318(1):80-8. doi: 10.1006/abbi.1995.1207.
Rubredoxin is a small nonheme iron protein that serves as an electron carrier in bacterial systems. Rubredoxin has now been isolated and characterized from the strictly anaerobic phototroph, Heliobacillus mobilis. THe molecular mass (5671.3 Da from the amino acid sequence) was confirmed and partial formylation of the N-terminal methionyl residue was established by matrix-assisted laser desorption mass spectroscopy. The complete 52-amino-acid sequence was determined by a combination of N-terminal sequencing by Edman degradation and C-terminal sequencing by a novel method using carboxypeptidase treatment in conjunction with amino acid analysis and laser desorption time of flight mass spectrometry. The molar absorption coefficient of Hc. mobilis rubredoxin at 490 nm is 6.9 mM-1 cm-1 and the midpoint redox potential at pH 8.0 is -46 mV. The EPR spectrum of the oxidized form shows resonances at g = 9.66 and 4.30 due to a high-spin ferric iron. The amino acid sequence is homologous to those of rubredoxins from other species, in particular, the gram-positive bacteria, and the phototrophic green sulfur bacteria, and the evolutionary implications of this are discussed.
红素氧还蛋白是一种小型非血红素铁蛋白，在细菌系统中作为电子载体。红素氧还蛋白现已从严格厌氧的光合生物——运动太阳杆菌中分离出来并进行了表征。通过基质辅助激光解吸质谱法确认了其分子量（根据氨基酸序列为5671.3道尔顿），并确定了N端甲硫氨酰残基的部分甲酰化。通过埃德曼降解法进行N端测序以及使用羧肽酶处理结合氨基酸分析和激光解吸飞行时间质谱法的新方法进行C端测序，确定了完整的52个氨基酸序列。运动太阳杆菌红素氧还蛋白在490nm处的摩尔吸收系数为6.9 mM-1 cm-1，在pH 8.0时的中点氧化还原电位为-46 mV。氧化形式的电子顺磁共振光谱在g = 9.66和4.30处显示共振，这是由于高自旋铁离子所致。该氨基酸序列与其他物种的红素氧还蛋白同源，特别是革兰氏阳性细菌和光合绿硫细菌，并讨论了其进化意义。
