This week in Science, a retraction due not to misconduct [see discussion below – an investigation could follow] but to the community of science working as it should:
We wish to retract our Report “Computational design of a biologically active enzyme” [MA Dwyer, LL Looger, HW Hellinga, Science 304, 1967 (2004)], which describes triose phosphate isomerase activity in a computationally redesigned ribose-binding protein (RBP) from E. coli. Dr. John P. Richard (Dept of Chemistry, Dept of Biochemistry, SUNY Buffalo), to whom we provided clones encoding the novoTIM activity, has brought to our attention that the triose phosphate isomerase activity observed in our reported preparations can be attributed to a wild-type TIM impurity–seen in preparations that use a continuous rather than stepwise imidazole gradient (as in the original paper) or that add a second sepharose column. Richard’s reanalysis has now also been confirmed by others in the Hellinga laboratory. The interpretations in the original report were based on lack of observed activity in mutant, engineered enzyme that bound substrate, but lacked catalytic residues. Variations in expression levels of designed proteins relative to the amount of contaminating endogenous protein might account for the pattern of observed activities that led to our erroneous conclusions. The in vivo experiments have not been reexamined.
We deeply regret that our report of a designed enzyme activity does not live up to closer scrutiny. Nevertheless, we remain optimistic that the problem of structure-based design of enzyme activity will be solved and that novel catalysts will be produced in conjunction with computationally based methods.
Mary A. Dwyer, Dept of Pharmacology and Cancer Biology, Duke Univ Med Ctr
Loren L. Looger, HHMI, Janelia Farm
Homme W. Hellinga, Dept of Biochemistry, Duke Univ Med Ctr