The swivel sugar is observed in a large number of positions. The two mannosides closest to the active-site zinc are shown for the α(1,6)-linked compounds 2 (green) and 5 (yellow) and for the α(1,3)-linked compounds 1 (cyan) and 3 (slate). In all cases, the position of the zinc-bound −1 mannoside is almost invariant, whereas the mannoside in the +1 site, which is described as the swivel residue, is highly variable. The oxygen at the cleavage site, indicated by an asterisk, is in almost the same position in all complexes.