Unlike most polar liquids, excess electrons in liquid CH3CN take on two distinct forms − solvated electrons (esolv − ) and solvated molecular anions − that are in equilibrium with each other. We find that excitation of esolv − leads to a short-lived excited state that has no effect on the equilibrium but that excitation of the molecular anion instantaneously leads to the production of new esolv...

The nonenzymatic reaction of ATP with a nucleophile to generate ADP and a phosphorylated product proceeds via a dissociative transition state with little bond formation to the nucleophile. Consideration of the dissociative nature of the nonenzymatic transition state leads to the following question: To what extent can the nucleophile be activated in enzymatic phosphoryl transfer? We have address...

SUMOylation is a highly transient post-translational protein modification. Attachment of SUMO to target proteins occurs via a number of specific activating and ligating enzymes that form the SUMO-substrate complex, and other SUMO-specific proteases that cleave the covalent bond, thus leaving both SUMO and target protein free for the next round of modification. SUMO modification has major effect...

The compression of a crystalline material under hydrostatic pressure always results in a reduction in volume of the solid, with the observed reduction typically occurring in all crystallographic cell parameters. However, there are a number of exceptional materials that have been shown to expand in a specific direction upon hydrostatic compression while maintaining a positive volume compression....

PYK (pyruvate kinase) plays a central role in the metabolism of many organisms and cell types, but the elucidation of the details of its function in a systems biology context has been hampered by the lack of specific high-affinity small-molecule inhibitors. High-throughput screening has been used to identify a family of saccharin derivatives which inhibit LmPYK (Leishmania mexicana PYK) activit...

The essential components of the Stoddart-Heath-type [2]rotaxane molecular switch tunnel junction devices are the aromatic shuttle and stations, which are attached to other components, such as linkers, stoppers, and anchors. In this study, we explored a possibility of whether the molecular switch can be made simple by leaving only the π-stacked aromatic key components between two metal electrode...

BACKGROUND The family of ubiquitin-like molecules (UbLs) comprises several members, each of which has sequence, structural, or functional similarity to ubiquitin. ISG15 is a homolog of ubiquitin in vertebrates and is strongly upregulated following induction by type I interferon. ISG15 can be covalently attached to proteins, analogous to ubiquitination and with actual support of ubiquitin conjug...

Selective covalent bond formation at a protein-protein interface potentially can be achieved by genetically introducing into a protein an appropriately "tuned" electrophilic unnatural amino acid that reacts with a native nucleophilic residue in its cognate receptor upon complex formation. We have evolved orthogonal aminoacyl-tRNA synthetase/tRNACUA pairs that genetically encode three aza-Michae...

The crystal structure of the human adenovirus proteinase (AVP), a cysteine proteinase covalently bound to its 11-amino-acid peptide cofactor pVIc, has been solved to 1.6-A resolution with a crystallographic R-factor of 0.136, R(free)=0.179. The fold of AVP-pVIc is new and the structural basis for it is described in detail. The polypeptide chain of AVP folds into two domains. One domain contains...