Related Experiment Video
Updated: Aug 16, 2026

Sequence-specific Labeling of Nucleic Acids and Proteins with Methyltransferases and Cofactor Analogues
Published on: November 22, 2014
Adenosylcobalamin-dependent isomerases: new insights into structure and mechanism
1Department of Chemistry and Division of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA. nmarsh@umich.edu
Abstract:
Adenosylcobalamin-dependent isomerases catalyze a variety of chemically difficult 1,2-rearrangements that proceed through a mechanism involving free radical intermediates. These radicals are initially generated by homolysis of the cobalt-carbon bond of the coenzyme. Recently, the crystal structures of several of these enzymes have been solved, revealing two modes of coenzyme binding and highlighting the role of the protein in controlling the rearrangement of reactive substrate radical intermediates. Complementary data from kinetic, spectroscopic and theoretical studies have produced insights into the mechanism by which substrate radicals are generated at the active site, and the pathways by which they rearrange.
Related Concept Videos
Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Cooperative Allosteric Transitions
Cooperative Allosteric Transitions
Allosteric Proteins-ATCase
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
Cooperative Allosteric Transitions
Aldehydes and Ketones with Amines: Enamine Formation Mechanism

