Researchers Develop Tunable Redox Proteins Using Non-Natural Porphyrins
Scientists have demonstrated that substituting natural heme B with a series of non-natural metalloporphyrins in de novo designed proteins can tune electron transfer potentials across a range of over 400 millivolts. The work used X-ray crystallography and NMR spectroscopy to confirm that the non-natural porphyrins bind with high affinity without disrupting the protein's structure or binding site. This establishes a modular platform for building customizable electron carriers relevant to engineered bioenergetic pathways and bioelectronic applications.
A study published on bioRxiv reports that replacing heme B with structurally conservative non-natural metalloporphyrins in two de novo designed proteins—the monoheme m4D2 and the diheme 4D2 T19D—enables broad modulation of redox potentials spanning more than 400 mV. The non-natural porphyrins were shown to bind with high affinity while preserving both the heme binding site geometry and the overall protein fold, as confirmed by X-ray crystallography and NMR spectroscopy. The researchers also determined the native-like NMR solution structure of m4D2 loaded with iron 2,4-dimethyldeuteroporphyrin IX, a symmetric non-natural porphyrin, further validating the modular design strategy. The tetrahelical scaffold used in both proteins proved compatible with a range of porphyrin substitutions, suggesting the approach is broadly applicable. The authors propose this platform as a versatile tool for constructing tuneable electron carriers for synthetic bioenergetics and bioelectronics.
What's missing
As a preprint, this work has not yet undergone peer review, so the findings should be treated as preliminary. The study does not report functional electron transfer rates or in vivo performance of the engineered proteins, leaving open questions about how well the redox tuning translates to practical bioenergetic or bioelectronic contexts.
What different sources said
- bioRxivCenter
Porphyrin driven redox tuning in structurally defined de novo heme proteins
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