We characterized a glycoside hydrolase family 112 protein from Opitutus terrae (Oter_1377 protein). The enzyme phosphorolyzed D-galactosyl-beta 1 -> 4-L-rhamnose (GalRha) and also showed phosphorolytic activity on D-galactosyl-beta 1 -> 3-D-glucose as a minor substrate. In the reverse reaction, the enzyme showed higher activity on L-rhamnose derivatives than Oil D-glucose derivatives. The enzyme was stable up to 45 degrees C and at pH 6.0-7.0. The values of k(cat) and K-m of the phosphorolytic activity of the enzyme on GalRha were 60 s(-1) and 2.1 mM, respectively. Thus, Oter_1377 protein was identified as D-galactosyl-beta 1 ->-4-L-rhamnose phosphorylase (GalRhaP). The presence of GalRhaP in O. terrae suggests that genes encoding GalRhaP are widely distributed in different organisms. (C) 2009 Elsevier Inc. All rights reserved.