Structural and Thermodynamic Characterization of T4 Lysozyme ...

Table 2. Cavity Volumes of T4 lysozyme MutantsCav. # WT*(1L63)WT*(MC) aL99A(1L90)L99G/E108V(1QUH)A98L(1QS5)V149G(1G0P)Comments0 21044.0 21113.6 21103.3 20866.9 20919.7 21312.7 Protein Surface1 50.3 (0) 44.9 (0) 51.9 (0) 47.5 (0) 46.8 (0) 49.2 (0) Sol-171, 1792 4.6 - - - 10.4 -3 25.3 (0) 22.2 (0) 27.6 (0) 23.6 (0) 37.8 (0) 106.3 (0) b Sol-208, Trp1384 25.8 (0) 29.3 (4.2) 26.7 (0) - - 27.5 (0) Sol-1755 7.1 11.9 9.2 - 7.7 9.66 39.2 39.1 161.1 222.5 (87.2) c 53.7 40.77 24.6 23.9 28.9 24.3 24.3 25.0 Trp1268 - - - 5.0 (0) 7.1 (0) - Sol-2139 - - - 5.5 8.5 -10 - - - - 12.1 -Volumes in Å 3 of molecular surfaces found in crystallographic structures (Experimental Procedures)of T4 lysozyme mutants with internal solvent molecules removed. Volumes of solvent-containing cavitydetermined with internal solvent molecules kept in the structures are shown inside the parentheses. Themolecular surfaces were found using a 1.2 Å probe in MSMS (34). Molecular surface 0 is the outersurface of the proteins, while 1 - 10 were cavities isolated from the external solvent. Surfaces detectedby MSMS but found to intersect with the external surface of the protein are not shown. a WT* structurewas provided by Marcus Collins (private communication). b Cavity 3 in V149G contained Sol 323(alternative site 423) and 324 according to the crystal structure. c Similarly, cavity 6 in L99G/E108Vcontains Sol 401 and 402.36