Complex sentence: The reactions of this pathway are mostly enzyme-catalyzed in modern cells, however, they also occur non-enzymatically under conditions that replicate those of the Archean ocean, and are catalyzed by metal ions, ferrous ions (Fe (II)) in particular.
Split into simpler sentences: The reactions of this pathway are mostly enzyme-catalyzed in modern cells. They also occur however non-enzymatically under conditions that replicate those of the Archean ocean, and are catalyzed by metal ions, ferrous ions (Fe (II)) in particular.