And in the first step of step three, we take the isocytrade and we reacted with the nicotine amide adenine dinucleotide in the oxidized form. And so in this process, the NAD plus is actually reduced into the NADH, and the isocitrate molecule is oxidized to form the oxylosuxanate. And we also release this H plus ion. So the first reaction involves abstraction of a pair of high energy electrons to form the NADH. And this high energy intermediate known as oxalosuxnate and oxylosuxanate is unstable because it is a beto keto acid. So remember from organic chemistry that beta keto acids are generally unstable molecules.