Dissolved low-molecular weight thiol concentrations from the U.S. GEOTRACES North Atlantic Ocean zonal transect

Abstract

Low-molecular weight thiols, including cysteine and glutathione, are biomolecules involved in a variety of metabolic pathways and act as important antioxidant and metal buffering agents. In this last capacity, they represent a potential mechanism for modulating the bioavailability and biogeochemistry of many trace elements in the ocean, particularly for chalcophilic elements (e.g., Cu, Zn, Cd, Ag and Hg). For this reason, and in the context of the international GEOTRACES program that seeks to understand the biogeochemistry of trace elements in the ocean, we measured the concentration of individual dissolved low-molecular weight thiols during the U.S. GEOTRACES North Atlantic Zonal Transect (USGNAZT). Only two thiols were identified, cysteine and glutathione, in contrast to results from the northeast subarctic Pacific Ocean, where the dipeptides glycine-cysteine and arginine-cysteine were also present and -glutamylcysteine was dominant. Concentrations of cysteine and glutathione in the North Atlantic Ocean were lower than in the Pacific and ranged from below detection (~0.01 nM) to 0.61 nM of cysteine and up to 1.0 nM of glutathione, with cysteine generally more abundant than glutathione. Vertical profiles of cysteine and glutathione were broadly consistent with their biological production, being more abundant in surface water and usually below detection at

Chemical Diversity and Biochemical Transformation of Biogenic Organic Sulfur in the Ocean

“…GSH is the most abundant particulate thiol in the ocean, while Cys and γ-Glu-Cys are primarily found dissolved (Dupont et al, 2006). Dissolved γ-Glu-Cys concentrations up to 15 nM have been measured in the northeast Pacific Ocean (an area of high productivity); in this region, Cys and GSH concentrations ranged from below detection limits (∼0.01 nM) up to 1 nM, consistent with levels reported in other ocean regions (Swarr et al, 2016). Previous estimates of dissolved Met concentrations ranged from 0.01 to 1 nM in surface waters (Valle et al, 2015).…”

Mercury isotope signatures record photic zone euxinia in the Mesoproterozoic ocean

“…Furthermore, the speciation of Hg(II) in oxic seawater is not well understood. Thiols and sulfide have been detected at subnanomolar level in modern surface ocean (24). However, it has been suggested that almost all thiols and sulfide in oxic seawater are complexed with more abundant metal ions (e.g., copper) (25,26).…”

Aquatic indirect photochemical transformations of natural peptidic thiols: impact of thiol properties, solution pH, solution salinity and metal ions

“…Thiols are group of biogenic sulydryl-containing compounds with multiple essential functions in biogeochemical systems. [1][2][3][4] Marine microbes such as phytoplankton contain high concentrations (mM to mM) of thiols (Table 1) such as cysteine (Cys), gglutamylcysteine (gEC), arginylcysteine (RC), glutathione (GSH), and phytochelatins (PC). In particular, the tripeptide GSH has high intracellular concentrations (780-3300 mM) 5 and plays important roles in detoxifying xenobiotics, 6 depleting reactive oxygen species (ROS), 7 mediating redox signaling, 8 and serving as a precursor for PC synthesis.…”