+Current address: Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, England.
++Current address: Department of Crystal and Structural Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
+++Current address: Department of Biochemistry, Chinese University of Hong Kong, New Territories, Hong Kong SAR, People's Republic of China.
++++Dr Veronica Lam is missing following the Indian Ocean tsunami of 26 December 2004. We wish to record here her important contribution to research on human G6PD.
1Residue numbers in roman type are for the human enzyme; those in italics are for the L. mesenteroides enzyme.