是動物體內一種結構簡單的含硫氨基酸,具有多種生物活性,能明顯促進神經系統的生長發育和細胞增殖、分化。(It is a kind of simple sulfur-containing amino acid in animal body. It has a variety of biological activities and can obviously promote the growth and development of nervous system and cell proliferation and differentiation.)