To initiate this study, we built an in-house collection of TPPdependent enzymes including PpBFD, PfBAL, ApPDC, ZmPDC, MenD, YerE, PigD and CDH (see the SI for their phylogenetic analysis) and their key mutants as revealed by prior studies. TPP enzymes from our collection are capable of facilitating benzoin condensation or Stetter reaction via a two- electron mechanism with excellent stereocontrol and a relatively broad substrate scope. We evaluated the performance of these TPP-dependent enzymes in our proposed photobiocatalytic radical alkylation (Table ). Using benzaldehyde 1a, Nhydroxyphthalimide ester 2a as the model substrate and fluorescein (3a) as the photocatalyst, among the wild-type TPP enzymes we examined, benzaldehyde lyase from Pseudomonas fluorescence (PfBAL) was the only enzyme furnishing appreciable initial activity towards 4a, albeit with modest enantioselectivity (11% yield, 25:75 e.r., Table , entry 1). Although the wild-type benzoylformate decarboxylase from Pseudomonas putida (PpBFD) did not provide product 4a (entry 2), its H281A mutant exhibited the highest activity and enantioselectivity (16% yield, 96:4 e.r., entry 3). Interestingly, PpBFD H281A and wt PfBAL showed opposite enantiopreference in this asymmetric radical alkylation process. Using PpBFD H281A as the biocatalyst, we further evaluated other photoredox catalysts in this radical alkylation reaction. It was found that Eosin Y (3b) and Eosin B (3c) were also effective in promoting this transformation (13% yield, 96:4 e.r. and 12% yield, 96:4 e.r., respectively, entries 4 and 5), although with a slightly reduced efficiency. Other photoredox catalysts (3d-3e) including our previously used rhodamine B (3d) were found to be ineffective (entry 6-7, see the SI for further details). Replacing 2a with its tetrachlorinated analog 2a' resulted in lower yield (7%) and identical enantioselectivity (entry 8). Furthermore, performing this photobiocatalytic reaction under slightly basic conditions led to an improved yield of 4a (entries 9 and 10). Unlike our previously developed system for pyridoxal radical biocatalysis, irradiation at a longer wavelength (525 nm) provided product with nearly identical yield and enantioselectivity (entry 11). Finally, at pH 8.5, with 2 mol% PpBFD H281A and 5 mol% fluorescein, 4a formed in 39% yield and 96.5:3.5 e.r. (entry 12).