Glutamine synthetase enzyme. Computer artwork of a molecule of glutamine synthetase, the so-called snowflake molecule. This is a ligase enzyme, that is an enzyme that forms chemical bonds between molecules. It plays an important role in the metabolism of nitrogen by catalyzing the condensation of glutamate and ammonia to form glutamine. The different colours show the different subunits that comprise the protein. Proteins form the majority of the structural and functional units in all organisms. Study of the structure and function of proteins (proteomics) provides greater insight into how organisms work.