Another vital property of nitrogen as a basic element of life is its ability to form hydrogen bonds. Hydrogen bonds between amino acids control the folding of proteins into a-helices and -sheets. In DNA, the hydrogen bonds to nitrogen are of even more importance. The realization that adenine only paired with thymine and that cytosine only paired with guanine (Watson-Crick pairing) was one of the keys to deciphering the structure of DNA. Base pairing through the hydrogen bonds of the nitrogen bases is also essential for the transmission of genetic information from DNA to messenger RNA and hence to instruct the protein synthesis factory.