Photocatalytic Hydrogen Evolution by a De Novo Designed Metalloprotein that Undergoes Ni-Mediated Oligomerization Shift

Pallavi Prasad, Leigh Anna Hunt, Ashley E. Pall, Maduni Ranasinghe, Ashley E. Williams, Timothy L. Stemmler, Borries Demeler, Nathan I. Hammer, Saumen Chakraborty

Research output: Contribution to journalArticlepeer-review

Abstract

De novo metalloprotein design involves the construction of proteins guided by specific repeat patterns of polar and apolar residues, which, upon self-assembly, provide a suitable environment to bind metals and produce artificial metalloenzymes. While a wide range of functionalities have been realized in de novo designed metalloproteins, the functional repertoire of such constructs towards alternative energy-relevant catalysis is currently limited. Here we show the application of de novo approach to design a functional H2 evolving protein. The design involved the assembly of an amphiphilic peptide featuring cysteines at tandem a/d sites of each helix. Intriguingly, upon NiII addition, the oligomers shift from a major trimeric assembly to a mix of dimers and trimers. The metalloprotein produced H2 photocatalytically with a bell-shape pH dependence, having a maximum activity at pH 5.5. Transient absorption spectroscopy is used to determine the timescales of electron transfer as a function of pH. Selective outer sphere mutations are made to probe how the local environment tunes activity. A preferential enhancement of activity is observed via steric modulation above the NiII site, towards the N-termini, compared to below the NiII site towards the C-termini.

Original languageEnglish
Article numbere202202902
Pages (from-to)e202202902
JournalChemistry - A European Journal
Volume29
Issue number14
DOIs
StatePublished - Mar 7 2023

Keywords

  • de novo proteins
  • photocatalysis
  • self-assembly
  • solar H
  • transient absorption kinetics
  • Metalloproteins/chemistry
  • Hydrogen
  • Metals
  • Peptides/chemistry
  • Cysteine/chemistry

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