Oscillatory rheology was then used to assess the viscoelastic properties of the hydrogels (Fig. ). The two enantiomers displayed similar behaviour. Time sweeps revealed immediate gelation and an increasing elastic modulus (G') over one hour until 34.3 ± 5.0 kPa for hFF, and 34.9 ± 3.4 kPa for Hff. By contrast, the racemic mixture displayed a 15-min. lag time, with G' reaching a plateau after ~3h. Remarkably, G' of the racemic mixture reached 592 ± 45 kPa, corresponding to a ~17-fold increase relative to each enantiomer alone. Furthermore, stress sweeps demonstrated that the racemic gel displayed also enhanced resistance against applied stress, with gel-to-sol transition occurring above 300 Pa, in contrast with each enantiomer whose moduli dropped at 70 Pa. Overall, the enhancement in the viscoelastic properties was consistent with the expected behaviour for the co-assembled rippled β-sheet.17 Singlecrystal X-ray diffraction is the technique of choice to confirm the enantiomeric peptide alternation in the stacks,24 but unfortunately all our attempts to crystallize Hff, hFF, or their racemic mixture were unsuccessful. Finally, we tested the assemblies for catalytic hydrolysis of p-nitrophenyl acetate (pNPA) as a chromogenic substrate (Fig. ). The parent compound Hff-COOH was reported to display a kobs = 3.5•10-4 s-1 when tested in the form of fibrils (25 mM) with 0.2 mM pNPA.17 C-terminally amidated Hff performed similarly, also at two-fold concentration to yield a hydrogel (i.e., kobs = 3.6•10-4 s-1).18 In this work, when tested with 1 mM pNPA, both Hff and hFF fibrils (25 mM) displayed a kobs = 4.5•10-4 s-1. Remarkably, the racemic mixture with the same peptide total concentration (i.e. = 25 mM obtained from 12.5 mM of each enantiomer) showed a further improvement by over 50% corresponding to a kobs = 7.0•10-4 s-1. To the best of our knowledge, this is the first report of a self-assembled catalyst whereby the racemic mixture displays improved catalysis relative to each enantiomer alone, which suggests the presence of organized co-assembled peptide fibrils, in agreement with spectroscopic and microscopic data that are compatible with the presence of rippled β-sheets. The presence of more hydrophobic pockets in the co-assembled catalyst that could favor substrate binding, and lead to enhanced catalysis, was then verified by fluorescence measurements using 8-anilinonaphthalene-1sulfonate ammonium salt (ANS). The use of this fluorofore is well-established to monitor the formation of hydrophobic environments, such as those arising upon peptide self-assembly.26,27 In particular, ANS fluorescence undergoes a blue-shift and increase in intensity when it is located in more hydrophobic environments,28 and this was also our case, as shown in Fig. . ANS alone displayed a mild fluorescence with a broad peak centred at 475 nm in the 450-500 nm range. A blueshift to 455 nm occurred when ANS was embedded in peptide assemblies, and fluorescence intensity increased 2-fold and 3-fold, in case of enantiopure and racemic assemblies, respectively. We inferred the presence of more hydrophobic pockets in the latter, as expected for rippled β-sheets. In conclusion, this proof of concept work describes the spectroscopic, microscopic, and rheological behaviour of a racemic mixture composed of a minimalistic tripeptide sequence that bears His for hydrolase mimicry,6,29,30 and Phe-Phe31,32 as a self-assembling motif. All the data support the formation of a rippled β-sheet, which was already described as a useful type of assembly for racemic tripeptides,24 as well as longer peptides to yield supramolecular hydrogels with increased stiffness.16 Importantly, this is the first work that proposes the use of racemic minimalistic tripeptide co-assemblies for enhanced biocatalysis, thus opening the way to the use of this approach to develop green catalysts. Given that peptide catalysts' optimization based on expert-knowledge-guided discovery is not trivial, we anticipate that integration with machine-learning approaches will be key to speed up advances in the field. The vast progress in peptide modelling methods,35 with the concomitant generation of curated datasets for catalytic peptides36 are important steps ahead to enable rapid developments. Indeed, combination of in silico and experimental approaches is already being successful to shed new light on the structure-activity relationship of catalytic amyloids,37 and looks promising to unveil key mechanistic details to unlock their full potential in various applications.