Publication Abstract from PubMed
BACKGROUND: The triosephosphate isomerase (TIM) fold is found in several different classes of enzymes, most of which are oligomers; TIM itself always functions as a very tight dimer. It has recently been shown that a monomeric form of TIM ('monoTIM') can be constructed by replacing a 15-residue interface loop, loop-3, with an eight-residue fragment; modelling suggests that this should result in a short strain-free turn, resulting in the subsequent helix, helix-A3, having an additional turn at its amino terminus. RESULTS: The crystal structure of monoTIM shows that it retains the characteristic TIM-barrel (betaalpha)8-fold and that the new loop has a structure very close to that predicted. Two other interface loops, loop-1 and loop-4, which contain the active site residues Lys13 and His95, respectively, show significant changes in structure in monoTIM compared with dimeric wild-type TIM. CONCLUSION: The observed structural differences between monoTIM and wild-type TIM indicate that the dimeric appearance of TIM determines the location and conformation of two of the four catalytic residues.
The crystal structure of an engineered monomeric triosephosphate isomerase, monoTIM: the correct modelling of an eight-residue loop.,Borchert TV, Abagyan R, Kishan KV, Zeelen JP, Wierenga RK Structure. 1993 Nov 15;1(3):205-13. PMID:16100954[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
