Figure 2.

Thermodynamics of the transition between the A and B states of CD44 HABD. Bottom row: In the A state, the Arg41 sidechain (tubes) is not in direct contact with oHA (balls-ands-sticks), whereas in the B state, the Arg41-containing loop is in a different conformation that facilitates direct contact. r is the distance between the Arg41 sidechain guanidinium central Cζ atom and the ether oxygen atom in the glycosidic linkage connecting GlcNAc3 to GlcUA4 in the bound oHA. Middle row: conformational free energies for the wildtype, ordered (left) and wildtype, partially disordered (right) forms of HABD. Free-energy values are in kcal/mol, contours are every 1 kcal/mol, and data are from Ref. (42). Top row: ordered (left) and partially disordered (right) forms of HABD (ribbons) with bound HA (balls-and-sticks).