The EndS encoding sequence was isolated from Sinorhizobium meliloti M5NICS DNA. Comparisons between the deduced amino acid sequence of the mature EndS (337 amino acids, molecular mass 36,418 Da. isoelectric point 4.92) and those of published beta-glycanases showed that this enzyme belongs to family 5 of the glycoside hydrolases. The protein was overproduced in Escherichia coli using a T7 expression system. When the purified overexpressed EndS protein was tested on cellulose-type components. the best substrate was CM-cellulose.