Vitamin amino acids. Most vitamins are not single molecules, but groups of related molecules called vitamers. For example, vitamin E consists of four tocopherols and four tocotrienols. The thirteen vitamins required by human metabolism are: vitamin A (retinols and carotenoids), vitamin B (thiamine), vitamin B (riboflavin), vitamin B (niacin), vitamin B (pantothenic acid), vitamin B (pyridoxine), vitamin B (biotin), vitamin B (folic acid or folate), vitamin B (cobalamins), vitamin C (ascorbic acid), vitamin D (calciferols), vitamin E (tocopherols and tocotrienols), and vitamin K (quinones). Vitamins have diverse biochemical functions. Some forms of vitamin A function as regulators of cell and tissue
Sagittarius B2 been detected in this feature. The European Space Agency's gamma-ray observatory INTEGRAL has observed gamma rays interacting with Sgr B2, causing x-ray emission from the molecular cloud. This energy was emitted about 350 years ago by the supermassive black hole (SMBH) at the galaxy's core, Sagittarius A*. The total luminosity from this outburst is an estimated million times stronger than the current output from Sagittarius A*. This conclusion has been supported in 2011 by Japanese astronomers who observed the galactic center with the Suzaku satellite. Sagittarius B2 Sagittarius B2 (Sgr B2) is a giant molecular cloud of gas and dust