Fig. 6.

The active site of Chit42. Detail of the crystal structure showing the proposed binding of a COS chain. Sugar was modelled into the active site by structural superimposition with the reported complex from S. marcescens ChiA (PDb code 1EIB). Molecular surface of Chit42 showing the sugar in magenta sticks. The catalytic Asp169 and Glu171 are in red (a). Details of atomic interaction between COS and Chit42 relevant residues are represented in sticks. Catalytic residues highlighted and proposed hydrogen links represented as dashed lines (b)