Abstract: Cysteine（Cys）,the final product of the sulfate assimilation pathway,widely exists in the organism. The oxidation state sulfur is absorbed and restored,and then integrated into the molecules skeletal structure of cysteine by organisms,participating in the other metabolic pathways of organisms. Because the structure of Cys contains thiol,which makes it being able to specifically bind with heavy metal ion,thus involving in the heavy metal resistance of organism,directly or indirectly. Considering a series of physiological and biochemical process in biological cells are orderly conducted under the heterogeneous condition,the investigation of Cys and the structure characteristics of Cys-M（M represents metal ion）complexes has significant reference value for studying Cys and the physiological behavior of Cys-M at the molecular level. In recent years,the application of new technique in the biological science,for example atomic force microscope（AFM）,makes this research feasible. In this paper,the basic characteristics and the biosynthetic pathway of Cys are introduced,concurrently,the research progress of Cys involved in heavy metal resistance are summarized,which aims to provide certain scientific theoretical basis for studying the detoxification mechanism of Cys in heavy metal resistance of organism.

Key words: cysteine, biosynthetic pathway, heavy metal resistance