Detection and Structural Elucidation of Copper Binding Tri- and Tetrapyrrole Ligands Produced by the Marine Diatom Phaeodactylum Tricornutum
Year: 2025
Type: article
Abstract: In seawater most dissolved copper (Cu) is complexed by organic ligands, many of which are thought to be produced by phytoplankton. Although very little is known about the composition and structure of these ligands, they play an important role in determining the reactivity and bioavailability of Cu. In this study, Phaeodactylum tricornutum, a marine diatom known to produce Cu ligands (CuLs), was grown in laboratory pure culture and the CuLs recovered from the growth media. Using liquid chromatography coupled to ultrahigh resolution tandem mass spectrometry, eleven Cu ligand complexes were identified and assigned molecular formulae. Molecular formulae were confirmed by comparing the expected and observed relative abundances of 15N, 13C, 65Cu, and 18O isotopologues. The CuLs had molecular weights from 520 to 719 Da and molecular formulae of C26-35H23-36O5-9N3-4Cu with an average assignment error of 56 ppb. High-resolution tandem mass spectrometry of the Cu-bound and metal-free ligands revealed these to be a suite of tri- and tetrapyrroles stabilized through complexation of Cu by N. The ligands share similar parent structures but differ in the number, type, and arrangement of functional groups that decorate the pyrroles. The similarity of CuL structures with known catabolites of chlorophyll suggests these ligands may be widely produced by marine photoautotrophs.
Authors: Lydia Babcock-Adams, Jingxuan Li, Amy M. McKenna, Christopher L. Hendrickson, Daniel J. Repeta
Language: English
Subfield: Oceanography
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Funders: National Science Foundation, Simons Foundation, National High Magnetic Field Laboratory, Division of Materials Research, Division of Ocean Sciences, Division of Chemistry, High Magnetic Field Laboratory, Chinese Academy of Sciences, National Science Foundation Graduate Research Fellowship Program, State of Florida
Awards: G1019936685, G1126480675, G1138554163, National High Magnetic Field Laboratory Renewal 2018-2022, G2660901070, Collaborative Research: US GEOTRACES GP-17-OCE: Molecular speciation of trace element-ligand complexes in the South Pacific Ocean, Graduate Research Fellowship Program, G354028113, G3560959519, G3937223104, G410635398, G4917416065, G5297888544, G5597825783, G593158620, G6010147111, G6055193757, National High Magnetic Field Laboratory Renewal 2023-2027, G742574937, Trace Element Organic Speciation along the US GEOTRACES Pacific Meridional Transect, G8152425740, G8515431097
OpenAlex ID: W4407534675