Cloning and Expression of a?-galactosidase Gene from Thermotoga maritima / 微生物学通报

The cloning and expression of a?-galactosidase gene(TM_0310)from Thermotoga maritima MSB8 was studied.The gene consists of 2019 bp,and the translated protein encodes 672 amino acids and its molecular mass is approximately 78.972 kD.The homology analysis of the deduced amino acid sequences showed that the enzyme shared 95%identity with a putative?-galactosidase from Thermotoga petrophila RKU-1 and a?-galactosidase from Thermotoga sp.RQ2.The galactosidase activity was up to 2.08 U/mg after the recombinant E.coli BL21 was induced by IPTG.The crude lysate remained about 70%activity after treated at 80℃for 10 min,indicating that the recombinant enzyme is thermostable and may be used at high temperatures.