Nicotinamide adenine dinucleotide phosphate Nicotinamide adenine dinucleotide phosphate, abbreviated NADP⁺ or, in older notation, TPN, is a cofactor used in anabolic reactions, such as lipid and nucleic acid synthesis, which require NADPH as a reducing agent.
So basically: NAPDH is the cell's "electron currency" for many synthesis processes (anabolic processes). It works like this: NADPH is able to chemically store a hydrogen cation as well as a hydrogen anion. by transferring both onto a chemical compound, two electrons are transferred (the H- ion got two electrons), and such, the compound is chemically reduced. (don't know what redox chemistry is? wikipedia helps you. :-) ) Our body does two kinds of general metabolism: Catabolic metabolism is 'digesting stuff'. Chemically: tranforming 'reduced' complex chemicals into 'oxidated' small chemicals plus energy. Anabolic metabolism ('building muscles up', for example) is the exact opposite: forging all the stuff that makes up our cells (mostly reduced complex chemicals) out of small chemical 'bricks', whose oxidation state is usually high. This is why, for catabolic processes, you need a compound (NAD+) that can yank electrones away from chemicals, while for anabolic processes, you need a different compound (NADPH) that can 'press' electrones into chemicals.
@schleifspur NADPH is not found in animals. You are confusing it with NADH, which does the exact job. You can keep them separate by associating the P with "plant". NADPH is used during photosynthesis and NADH is used during cellular respiration, fermentation, and glycolysis. The accepted reason for the evolution of this difference is that if both processes used NADPH only (or NADH only), then organisms performing photosynthesis would not be able to regulate their photosynthetic pathways separately from the glycolysis/cellular respiration/fermentation pathways.
yeah...right...except that almost every sentence of that reply is wrong :D - both NADH and NADPH are found in animals, plants, bacteria...that's two seconds worth looking at wikipedia articles for you =) - NADPH is not used, but BUILT during photosynthesis. In animals, building NADPH requires the pentose phosphate cycle (which is also present in plants, fyi) - the part where you talk about evolution is partly wrong. the organism doesn't THINK anything. the NADPH/NADP+ ratio simply elicits a greater reduction potential than NADH/NAD+, thus rendering it more suitable for anabolic reactions. there are, in fact, reactions that should not be catalyzable by NADH because its concentration in the cell is really low. apparently, they teach you a lot of wrong stuff in high school :-(
@schleifspur Well, you're right about the not being in animals, but I never said it was not in plants. I specifically mentioned the two separate pathways, which are in plants. However, NADPH is not a significant player in aerobic cellular respiration, as taught to students. You cannot even find "NADPH" on the wikipedia article about aerobic respiration. Also, if you check out here or other places, http://www.uic.edu/classes/bios/bios100/lectures/ps01.htm you can see how NADPH is used and reformed during the processes. It is formed during and used and reformed across the light dependent and light independent reactions of photosynthesis. It is not simply made. And for the evolution, please explain how regulation of cellular cycles = thinking. Under your treatment of regulation = conscience control, all organisms are actively thinking about how to maintain their cellular states necessary to perform all cellular activities. Obviously, regulatory systems evolved and did not involve thought. I did not complete the full explanation as I did not think it was necessary, but apparently it is. So, the ability to separately regulate systems would convey a fitness increase to organisms when compared to those that cannot. This fitness difference explains why it is more favorable to have independent regulation of cellular pathways. Basically, I focused on the most common areas NADPH/NADP+ and NADH/NAD+ show up in what students are taught, photosynthesis, glycolysis, etc. In those areas the difference of occurrence I mentioned is valid. However, as you rightfully pointed out those are not the only areas that one would encounter NADPH.
okay, another discussion I don't want to fight out...you were wrong in your first answer, then I called you on your bullpellet, then you desperately tried finding bullshit in my answer. end of discussion, but at least now you know a little bit more about NADPH. win-win. :-)