查看文章

Multiple-sequence alignment of glycoside hydrolase (GH) families 32, 43, 62, and 68 revealed three conserved blocks, each containing an acidic residue at an equivalent position in all the enzymes. A detailed analysis of the site-directed mutations so far performed on invertases (GH32), arabinanases (GH43), and bacterial fructosyltransferases (GH68) indicated a direct implication of the conserved residues Asp/Glu (block I), Asp (block II), and Glu (block III) in substrate binding and hydrolysis. These residues are close in space in the 5-bladed-propeller fold determined for Cellvibrio japonicus-L-arabinanase Arb43A [Nurizzo et al., Nat Struct Biol 2002; 9: 665–668] and Bacillus subtilis endo-1, 5--L-arabinanase. A sequence–structure compatibility search using 3D-PSSM, mGenTHREADER, INBGU, and SAM-T02 programs predicted indistinctly the 5-bladed-propeller fold of Arb43A and the 6-bladed-propeller fold of …