The production of functional molecular architectures through self-assembly is commonplace in biology, but despite advances(1-3), it is still a major challenge to achieve similar complexity in the laboratory. Self-assembled structures that are reproducible and virtually defect free are of interest for applications in three-dimensional cell culture(4,5), templating(6), biosensing(7) and supramolecular electronics(8). Here, we report the use of reversible enzyme-catalysed reactions to drive self-assembly. In this approach, the self-assembly of aromatic short peptide derivatives(9,10) provides a driving force that enables a protease enzyme to produce building blocks in a reversible and spatially confined manner. We demonstrate that this system combines three features: (i) self-correctionfully reversible self-assembly under thermodynamic control; (ii) component-selection-the ability to amplify the most stable molecular self-assembly structures in dynamic combinatorial libraries(11-13); and (iii) spatiotemporal confinement of nucleation and structure growth. Enzyme-assisted self-assembly therefore provides control in bottom-up fabrication of nanomaterials that could ultimately lead to functional nanostructures with enhanced complexities and fewer defects. ; Times Cited: 145 Ulijn, Rein/C-3998-2009; Smith, Andrew/C-8945-2009 0 147