Antibody 43C9 accelerates the hydrolysis of a p-nitroanilide by a factor of 2.5 x 10(5) over the background rate in addition to catalyzing the hydrolysis of a series of aromatic esters. Since this represents one of the largest rate accelerations achieved with an antibody, we have undertaken a series of studies aimed at uncovering the catalytic mechanism of 43C9. The immunogen, a phosphonamidate...

The presence of latent activities in enzymes is posited to underlie the natural evolution of new catalytic functions. However, the prevalence and extent of such substrate and catalytic ambiguity in evolved enzymes is difficult to address experimentally given the order-of-magnitude difference in the activities for native and, sometimes, promiscuous substrate/s. Further, such latent functions are...

The increased rate of hydrolysis of organic phosphate compounds in the presence of molybdate has been observed frequently and is the basis for the estimation of phosphocreatine (1) and acetyl phosphate (2) in tissue extracts. A study was undertaken to determine whether this was a general effect and, if so, to elucidate the mechanism. While these experiments were in progress, Weil-Malherbe and G...

The enzymes that facilitate phosphate and sulfate hydrolysis are among the most proficient natural catalysts known to date. Interestingly, a large number of these enzymes are promiscuous catalysts that exhibit both phosphatase and sulfatase activities in the same active site and, on top of that, have also been demonstrated to efficiently catalyze the hydrolysis of other additional substrates wi...

Atlastin, a member of the dynamin superfamily, is known to catalyse homotypic membrane fusion in the smooth endoplasmic reticulum (ER). Recent studies of atlastin have elucidated key features about its structure and function; however, several mechanistic details, including the catalytic mechanism and GTP hydrolysis-driven conformational changes, are yet to be determined. Here, we present the cr...

Circular clamps are utilised by replicative polymerases to enhance processivity. The topological problem of loading a toroidal clamp onto DNA is overcome by ATP-dependent clamp loader complexes. Different organisms use related protein machines to load clamps, but the mechanisms by which they utilise ATP are surprisingly different. Using mutant clamp loaders that are deficient in either ATP bind...

-The effect of layer charge and of the interlayer cations of smectites on the hydrolysis of azinphosmethyl (0,0-dimethyl S-((4-oxo-1,2,3-benzotriazine-3(4H)-yl)methyl) phosphorodithioate) in an aqueous medium was investigated. Ultraviolet spectroscopy was used for monitoring the hydrolysis process. Hydrolysis of the pesticide is catalyzed by Ca-hectorite (layer charge 0.216) but is not catalyze...

The exopeptidases of family S46 are exceptional, as the closest homologs of these enzymes are the endopeptidases of clan PA. The three-dimensional structure of S46 enzymes is unknown and only one of the catalytic residues, the serine, has been identified. The catalytic histidine and aspartate residues are not experimentally identified. Here we present phylogenetic and experimental data that ide...

Many viruses package their genome into preformed capsids using packaging motors powered by the hydrolysis of ATP. The hexameric ATPase P4 of dsRNA bacteriophage phi12, located at the vertices of the icosahedral capsid, is such a packaging motor. We have captured crystallographic structures of P4 for all the key points along the catalytic pathway, including apo, substrate analog bound, and produ...

The efficient synthesis of two new stereoisomeric 3-aminocyclooctanetriols and their halocyclitol derivatives starting from cis,cis -1,3-cyclooctadiene are reported. Reduction cyclooctene endoperoxide, obtained by photooxygenation -1,3-cyclooctadiene, with zinc yielded a diol followed acetylation the hydroxy group, which gave dioldiacetate OsO 4 /NMO oxidation. cyclooctane prepared was converte...