NAS Election Citation: Collier's contributions include demonstrating that diphtheria toxin blocks protein synthesis by inactivating Elongation Factor-2; elucidating diphtheria toxin structure, as containing enzymatic (A) and binding (B) fragments; identifying Glu-l48 as a key active-site residue; developing A-chain immunotoxin concepts; crystallizing diphtheria and Pseudomonas toxins and determining Pseudomonas toxin's structure at 3 Angstrom.