References Amit, A G, Mariuzza, R A, Phillips, S E V, & Poljak, R J 1986. Science 233: 747-758 Aqvist, J & Tapia, O 1987. J. Mol. Graph.5: 31-34 Bricogne, G 1976. Acta Cryst. A32: 832-847 Bruccoleri, R E, & Karplus, M 1987. Biopolymers 26: 137-168 Bruccoleri, R E, Haber, E, & Novotny, J 1988. Nature 335: 564-568 Carbo, R, Leyda, L, & Arnau, M 1980. Int. J. Quantum Chem. 17: 1185 CCP4 1991. The Cooperative Computing Project in Crystallography Warrington, England: Daresbury Laboratory Chothia, C, & Lesk, A M 1987. J. Mol. Biol. 196: 901-917 Chothia, C, Lesk, A M, Tramontano, A, Levitt, M, Smith- Gill, S J, Air, G, Sheriff, S,Padlan, E A, Davies, D, Tulip, W R, Colman, P M, Spinelli, S, Alzari, P M, & Poljak, R J 1989. Nature 342: 877-883 Connolly, M 1983a. Science 221: 709-713 Connolly, M 1983b. J. Appl. Cryst. 16: 548-558 Connolly, M 1986. J. Mol. Graph. 4:3-6 Dean, P M, & Chau, P L 1987. J. Mol. Graphics 5: 152-164 Diamond, R 1971. Acta Cryst. A27: 436-52 Diamond, R 1976. Acta Cryst. A32: 1-10 Diamond, R 1988. Acta Cryst. A44: 211-6 Diamond, R 1989. Acta Cryst. A45: Epp, O, Latham, E, Schiffer, M, Huber, R, & Palm, W 1975. Biochemistry 14: 4943-52 Hodgkin, E E, & Richards, W G 1987. Int. J. Quantum Chem. Quantum Biol. Symp. 14: 105 Jones, T A, Zou, J Y, Cowan, S W, & Kjeldgaard, M 1991. Acta Cryst. A47: 110-9 Kearsley, S K 1989. Acta Cryst. A45: 208-210 Kearsley, S K 1990. J. Comp. Chem. 11:1187-92 Leicester, S E, Finney, J L, & Bywater, R P 1988. J. Mol. Graphics 6: 104-108 Lesk, A M 1986. Acta Cryst. A42: 110-3 Lewis, M, & Rees, D C 1985. Science 230: 1163-65 Martin, A C R, Cheetham, J C, & Rees, A R 1989. Proc. Nat. Acad. Sci. USA 86: 9268-9272 Max, N L 1984. J. Mol. Graphics 2: 13-Aug Max, N L & Getzoff, E D 1988. IEEE Comp. Graphics and Applications 8: 42-50 McLachlan, A D 1972. Acta Cryst. A28: 656-7 McLachlan, A D 1979. Acta Cryst. A38: 871-3 Milstein, C 1990. Proc. R. Soc. (London) B239:1-16: Muirhead, H, Cox, J M, Mazzarella, C & Perutz, M F 1967. J. Mol. Biol. 28: 117-156 Namasivayam, S & Dean, P M 1986. J. Mol. Graphics 4: 46-50 Padlan, E A, Silverton, E W, Sheriff, S, Cohen, G H, Smith-Gill, GS, & Davies, D R 1989. Proc. Natl. Acad. Sci. USA 86: 5938-5942 Pfeifer, P, Welz, U, & Wipperman, H 1985. Chem. Phys. Lett. 113: 535- 40 Press, W H, Flannery, B P, Teukolsky, S A, & Vetterling, W T 1988. Numerical Recipes in C. Cambridge: Cambridge UP Richards, F M 1977. Ann. Rev. Biophys. Bioeng. 6: 151-76 Rosenfeld, A, & Kak, A C 1982. Digital Picture Processing. (Second Edition, Volume 2) New York: Academic Press Satow, Y, Cohen, G H, Padlan, E A, & Davies, D R 1986. J. Mol. Biol. 190: 593-604 Sharp, K A, & Honig, B 1990. Annu. Rev. Biophys. Biophys. Chem. 19: 301-32 Wintz, P A 1969. Proc. IEEE 60: 809-820 Zhang, K Y J, & Main, P 1990. Acta Cryst. A46: 41-46