Oxygen activation by mononuclear Mn, Co, and Ni centers in biology and synthetic complexes

Abstract

The active sites of metalloenzymes that catalyze O-dependent reactions generally contain iron or copper ions. However, several enzymes are capable of activating O at manganese or nickel centers instead, and a handful of dioxygenases exhibit activity when substituted with cobalt. This minireview summarizes the catalytic properties of oxygenases and oxidases with mononuclear Mn, Co, or Ni active sites, including oxalate-degrading oxidases, catechol dioxygenases, and quercetin dioxygenase. In addition, recent developments in the O reactivity of synthetic Mn, Co, or Ni complexes are described, with an emphasis on the nature of reactive intermediates featuring superoxo-, peroxo-, or oxo-ligands. Collectively, the biochemical and synthetic studies discussed herein reveal the possibilities and limitations of O activation at these three "overlooked" metals.

Spectroscopic and computational studies of reversible O2 binding by a cobalt complex of relevance to cysteine dioxygenase

“…[24][25][26][27] Recent studies have demonstrated that the expression of CDO suppresses the growth of tumors, and downregulation of the CDO gene was observed in cancer cell lines. 28 Unlike other MNIDs that are active with non-native metal ions (e.g., Co or Mn), 29 CDO functions exclusively with iron; indeed, addition of Co(ii) salts inhibits CDO by displacing the Fe(ii) center from the active site. 30 Scheme 1 Reaction catalyzed by CDO.…”

The impact of simulation sequencing on perceived clinical decision making

“…[24][25][26][27] Recent studies have demonstrated that the expression of CDO suppresses the growth of tumors, and downregulation of the CDO gene was observed in cancer cell lines. 28 Unlike other MNIDs that are active with non-native metal ions (e.g., Co or Mn), 29 CDO functions exclusively with iron; indeed, addition of Co(ii) salts inhibits CDO by displacing the Fe(ii) center from the active site. 30 Experimental and computational studies have contributed to the proposed CDO mechanism shown in Scheme 2, although questions regarding the nature of key intermediates remain.…”

Harnessing the Coordination Chemistry of 1,4,7‐Triazacyclononane for Biomimicry and Radiopharmaceutical Applications

“…Nickel is present at the active sites of enzymes such as carbon monoxide dehydrogenase, urease and [Ni−Fe]‐hydrogenase, whereas manganese‐containing active sites are present in biological systems such as photosystem II, ribonucleotide reductase, superoxide dismutase and manganese catalases . Likewise, Zn II is present at the active sites of enzymes responsible for catalysing hydration reactions, RNA polymerization or phosphoryl transfer reactions, and μ‐oxo/hydroxo‐diiron motifs are present in non‐haem, non‐sulfur iron proteins that carry out specific functions such as dioxygen transport and storage (haemerythrin), alkane hydroxylation (methane monooxygenase), and phosphate ester hydrolysis (purple acid phosphatases) .…”