Chirality-Induced Magnetization of Magnetite by an RNA Precursor

Abstract

Life is homochiral and homochirality is a fundamental feature of living systems on Earth. While the exact mechanism that led to homochirality is still not fully understood, any realistic scenario on the origins of life needs to address the emergence of homochirality. In order to impose and maintain chirality in a prebiotic network, an environmental factor functioning as a chiral agent is demanded. Magnetized surfaces are prebiotically plausible chiral agents, shown to be effective in enantioseparation of ribose-aminooxazoline (RAO), a ribonucleic acid (RNA) precursor, due to the chiral-induced spin selectivity (CISS) effect. As such, mechanisms for breaking the magnetic symmetry of magnetic minerals are of the utmost importance. Here we report the avalanche magnetization of magnetite (Fe3O4) by the crystallization of enantiopure RAO. The observed breaking of the magnetic symmetry is induced by the chiral molecules due to the CISS effect and spreads out across the magnetic surface like an avalanche, providing a way to uniformly magnetize a magnetic surface without fully covering it. Considered together with our previous results on enantioseparation by crystallization on a magnetic surface, chirality-induced avalanche magnetization paves the way for a cooperative feedback between chiral molecules and magnetic surfaces. With this feedback, a weak natural bias in the net magnetization can be amplified and spin-selective processes can be accommodated on magnetic minerals on a persistent basis.

The central dogma of biological homochirality: How does chiral information propagate in a prebiotic network?

“…The data supporting the findings of this study were published in two separate works by the authors of this study 1,2 . The data are avaliable from the publisher and/or corresponding author (S.F.O.)…”

“…Moreover, the magnetization induced by the chiral molecules propagates like an avalanche, leading to a uniform magnetization that extends beyond the region covered by the RAO crystals. Our measurements of the surface magnetization also revealed that the surface magnetized by the chiral crystals has a higher magnetic resistance (coercivity) compared to a portion of the surface away from the chiral molecules 2 . The increase in the magnetic coercivity was measured to be about 1 mT which is about 20 times higher than the modern geomagnetic field, indicating that the induced surface magnetization will persist against possible geomagnetic reversals 46 .…”

“…In our initial work on enantioselective crystallization, we found that a magnetite surface magnetized by the north (south) pole of a magnet promotes the crystallization of D-RAO (L-RAO). To our delight, in our follow-up work, we observed that D-RAO (L-RAO) magnetizes the magnetite surface along the same direction as the north (south) pole of a magnet 2,35 . Therefore, the coupling between enantiomeric excess and net magnetization is mutually reinforcing, leading to the possibility of a cooperative feedback between chiral molecules and magnetic surfaces, as illustrated in Fig.…”

“…We obtained enantiopure RAO crystals from a fully racemic solution through a process controlled by electron spin, due to the CISS effect 1 . Moreover, we demonstrated a mechanism whereby RAO can uniformly magnetize Fe 3 O 4 surfaces, by utilizing the CISS effect in the opposite direction 2 . Thus, our previous work demonstrates that RAO could be a highly plausible chiral compound for achieving homochirality in a prebiotic chemistry network, where natural magnetic minerals, such as magnetite, could act as very effective chiral agents due to the CISS effect (Fig.…”

“…Recent findings on strong stereoselectivity in the attachment of amino acids to tRNA analogs 3 , combined with an RNA precursor capable of achieving robust and persistent homochirality by crystallizing on magnetized magnetite (Fe 3 O 4 ) surfaces 1,2 , provide for the first time an opportunity to demon- strate a prebiotically plausible pathway to network-level homochirality. In this paper we take a step further and use these experimental results to suggest that the homochirality achieved at the RNA precursor can propagate through RNA, then to peptides, and eventually to metabolites (Fig.…”