HealthWise Glycine is a 100% pure pharmaceutical-grade micro-crystalline powder. The principal function of glycine is to serve as a neurotransmitter and a precursor to proteins. This organic compound is also a vital building block for numerous natural products. if the amino acid serine is required by the body, it can be converted from glycine. Did you know? NASA scientists have discovered glycine in samples of comet Wild 2 returned by NASA's stardust spacecraft. "The discovery of glycine in a comet supports the idea that the fundamental building blocks of life are prevalent in space and strengthens the argument that life in the universe may be common rather than rare".