Substance X, in turn, donates its electron to an iron-containing protein called ferredoxin.
X物质又将它的电子转移给一种含铁的蛋白质，称为铁氧还蛋白。
2
Levels of a substance called pregnancy zone protein had been unusually high, even before their symptoms appeared, in some of those who went on to develop Alzheimer's disease.
Dr Yun plumped instead for a chemical called Green Flourescent Protein (GFP), the substance responsible for making certain species of jellyfish glow in the dark.