Glyoxalase Ⅰ(GLOI),an enzyme of the glyoxalase system,is involved in the cellular detoxication,and also plays an important role in the cell cycle and cellular growth.In order to explore the molecular structure and biological function of GLOI in molluscs,GLOI gene of Tegillarca granosa(Tg-GLOI)was cloned by SMART RACE techniques,and characteristics of its amino acid sequence and expression in different tissues and developmental stages were analyzed.The full length cDNA of Tg-GLOI was 1 807 bp,and its complete ORF(Open Reading Frame)was 540 bp encoding 180 amino acids.There was a conserved domain of glyoxalase family at the 27-169 aa in amino sequence of Tg-GLOI.Mature glyoxalase Ⅰ of T.granosa contains two identical subunits,and each subunit was encoded by GLOI gene.The second structure of Tg-GLOI contains eighteen α-helices,twenty parallel β-sheets and thirty-six corners,each of the subunits comprising a Zn²⁺,and the Zn²⁺ binding sites are located within the gap between subunits.Homologous analysis showed that the amino acid sequence of Tg-GLOI shared 86.1% similarity with Crassostrea gigas,and shared more than 70% similarity with those of vertebrates.The results of tissue-specific expression by real time PCR showed that Tg-GLOI gene was expressed in all tissues,and the expression of digestive gland was significantly higher than other tissues(P<0.01).The results of relative expression in different development stages revealed that the expression of Tg-GLOI gene was gradually increased with the process of development,and showed the highest expression in the eyebot larvae stage,which was significantly higher than other stages(P<0.01).And the expression decreased significantly from eyebot larvae stage to juvenile clams(P<0.01)and then stabilized.The results showed that Tg-GLOI had the similar molecular structure as the higher species,and the relative expression revealed significant differences in different tissues and development stages,which laid the theoretical foundation for further study on function and mechanisms of GLOI in molluscs.