Surface-hydration water molecules of the M20-open crystal at (a) 0.1, (b) 270, (c) 500, (d) 660 and (e) 750 MPa. The 0.1 and 270 MPa structures are of the B chain. The same surface of the M20-closed crystal at 650 MPa is also shown in (f). Water molecules are shown as cyan spheres. FOL and NADP+ are shown as stick models. The surface at Lys32 and Leu36 is colored green.