Biology subjects

Barayeu, U.

Publications and source records attributed to Barayeu, U..

3 recordsLinked to original sources

bioRxiv2024

Sulfite oxidase deficiency causes persulfidation loss and H2S release

Sulfite oxidase (SOX) deficiency is a rare inborn error of cysteine metabolism resulting in severe neurological damage. In patients, sulfite accumulates to toxic levels causing a raise in downstream products S-sulfocysteine (SSC), mediating excitotoxicity, and thiosulfate, a catabolic intermediate/product of H2S metabolism. Here, we report a full-body knock-out mouse model for SOX deficiency (SOXD) with a severely impaired phenotype. Amongst the urinary biomarkers, thiosulfate showed a 45-fold accumulation in SOXD mice representing the major excreted S-metabolite. Consistently, we found increased plasma H2S, which was derived from sulfite-induced release from persulfides as demonstrated in vitro and in vivo. Mass spectrometric analysis of total protein persulfidome identified a major loss of persulfidation in 20% of the proteome affecting enzymes in amino acids and fatty acid metabolism. Urinary amino acid profiles indicate metabolic rewiring suggesting partial reversal of the TCA cycle thus identifying a novel contribution of H2S metabolism and persulfidation in SOXD.

biochemistry↗

bioRxiv2023

Methane formation driven by light and heat prior to the origin of life

Methane is a potent greenhouse gas, which likely enabled the evolution of life by keeping the early Earth warm. Here, we demonstrate new routes towards abiotic methane formation under early-earth conditions from methylated sulfur and nitrogen compounds with prebiotic origin. These compounds are demethylated in Fenton reactions governed by ferrous iron and reactive oxygen species, produced by light and heat in aqueous environments. The reactions generate methyl radicals and ultimately release methane and ethane. Organic iron chelators enhance reaction rates and recycle ferric to ferrous complexes via ligand-to-metal charge transfer, establishing a light-driven iron redox cycle. This abiotic reaction facilitates methane and ethane formation across Earths humid realm, thereby shaping the chemical evolution of the atmosphere prior to the origin of life and beyond. One-Sentence SummaryUnder suboxic and anoxic conditions, iron and reactive oxygen species drive the global formation of methane in aqueous environments.

evolutionary biology↗

bioRxiv2023

DOPA residues endow collagen with radical scavenging capacity

Here we uncover collagen, the main structural protein of all connective tissues, as a redox-active material. We identify dihydroxyphenylalanine (DOPA) residues, post-translational oxidation products of tyrosine residues, to be common in collagen derived from different connective tissues. We observe that these DOPA residues endow collagen with substantial radical scavenging capacity. When reducing radicals, DOPA residues work as redox relay: they convert to the quinone and generate hydrogen peroxide. In this dual function, DOPA outcompetes its amino acid precursors and ascorbic acid. Our results establish DOPA residues as redox-active side chains of collagens, probably protecting connective tissues against radicals formed under mechanical stress and/or inflammation.

biophysics↗