Difunctionalizing carboxylation of alkynes with CO2 is a sustainable and important strategy to generate valuable acrylate derivatives from both readily available starting materials. Such protocols, however, always suffer the use excess metallic reagents transition metal residue. Herein, we report first thio-carboxylation thiophenols CO2, which visible-light-driven metal-free process. In contras...

The carboxylation of lysine residues is a post-translational modification (PTM) that plays a critical role in the catalytic mechanisms of several important enzymes. It occurs spontaneously under certain physicochemical conditions, but is difficult to detect experimentally. Its full impact is unknown. In this work, the signature microenvironment of lysine-carboxylation sites has been characteriz...

A gamma-carboxylation recognition site on the propeptide of the vitamin K-dependent blood coagulation proteins directs the carboxylation of glutamic acid residues by binding to the vitamin K-dependent carboxylase. To determine residues that define this site, we evaluated the effect of mutation of certain residues in the prothrombin propeptide on the extent of carboxylation. The prothrombin cDNA...

Pyruvate carboxylation in the isolated perfused rat heart was studied under steady-state conditions. A biotin deficiency resulting in a 90% decrease in myocardial pyruvate carboxylase left the pyruvate carboxylation rate unchanged. Pyruvate carboxylation in heart muscle must therefore take place by means of an enzyme which does not contain biotin. The kinetic properties and mass-action ratio of...

Prothrombin is a vitamin K-dependent blood coagulation protein that undergoes posttranslational y-carboxylation and propeptide cleavage during biosynthesis. The propeptide contains the y-carboxylation recognition site that directs y-carboxylation. To identify the intracellular sites of carboxylation and propeptide cleavage, we monitored the synthesis of prothrombin in Chinese hamster ovary cell...

Carbon dioxide (CO2 ) represents the most abundant and accessible carbon source on Earth. Thus the ability to transform CO2 into valuable commodity chemicals through the construction of C-C bonds is an invaluable strategy. Carboxylic acids and derivatives, the main products obtained by carboxylation of carbon nucleophiles by reaction of CO2 , have wide application in pharmaceuticals and advance...

The pentapeptide Phe-Leu-Glu-Glu-Leu, tritiated at the gamma carbon of each Glu residue, has been synthesized. In a system using microsomal preparations derived from rat liver, vitamin K-dependent tritium release from the L-Glu residues of this substrate can occur without the concurrent gamma-carboxylation of Glu. This tritium release reaction, which indicates cleavage of the gamma C-H bond, al...

The retinal pigment epithelium (RPE) is a monolayer of pigmented cells that requires an active metabolism to maintain outer retinal homeostasis and compensate for oxidative stress. Using 13C metabolic flux analysis in human RPE cells, we found that RPE has an exceptionally high capacity for reductive carboxylation, a metabolic pathway that has recently garnered significant interest because of i...

Vertebrates possess 2 proteins with vitamin K oxidoreductase (VKOR) activity: VKORC1, whose vitamin K reduction supports vitamin K-dependent (VKD) protein carboxylation, and VKORC1-like 1 (VKORC1L1), whose function is unknown. VKD proteins include liver-derived coagulation factors, and hemorrhaging and lethality were previously observed in mice lacking either VKORC1 or the γ-glutamyl carboxylas...

Gas exchange of Eurasian watermilfoil (Myriophyllum spicatum L.) indicated a near-zero CO(2) compensation point and a high temperature optimum for photosynthesis. These properties are characteristic of plants fixing CO(2) by a beta-carboxylation mechanism. Operation of the Calvin cycle was shown and no evidence for beta-carboxylation was obtained. These results indicate that near-zero CO(2) com...