A little biochem/metabolism question I am only asking here since my prof is a computer putz and had to cancel class twice now due to her ineptitude with the AV equipment. Ok..I understand what ATP is. I am getting confused where NADH comes in. I know it is a catalyst for ATP..the spark plug so to speak. It is an enzyme derived from what we eat. I am having difficulty understanding the substrate-level phosphorylation with regards to the enzyme relating to the production of energy. Can anyone provide me with a "dummy" website that is not all that dumb? As I said, I am trying to learn this on my own.