Studies with deuterium as a tracer have shown that wheat germ and pig heart malic dehydrogenase act on the keto form of oxaloacetic acid (1, 2). The keto form of this acid has also been shown to arise in the enzymatic carboxylation of phosphorylenolpyruvate by wheat germ phosphoryl-enolpyruvate carboxylase (3) and by avian liver phosphoryl-enolpyruvate carboxylase kinase (2). In an attempt to e...

We report the crystal structures of the phosporylated pyruvate dehydrogenase (E1p) component of the human pyruvate dehydrogenase complex (PDC). The complete phosphorylation at Ser264-alpha (site 1) of a variant E1p protein was achieved using robust pyruvate dehydrogenase kinase 4 free of the PDC core. We show that unlike its unmodified counterpart, the presence of a phosphoryl group at Ser264-a...

RNA ligase from T4-phage-infected Escherichia coli cells catalyzes the covalent joining of two polynucleotides that are partially hydrogen-bonded to each other. Two polynucleotide fragments derived from yeast tRNA(Phe) and consisting of residues 1-36 and 38-74 are covalently joined by the enzyme. The product of the reaction lacks residue Y(37) and has an anticodon loop with six nucleotide resid...

Phosphoroimidazolides play a critical role in several enzymatic phosphoryl transfer reactions and have been studied extensively as activated monomers for nonenzymatic nucleic acid replication, but the detailed mechanisms of these phosphoryl transfer reactions remain elusive. Some aspects of the mechanism can be deduced by studying the hydrolysis reaction, a simpler system that is amenable to a ...

The phosphorylation state of SpoIIAA is a key factor in the regulation of sporulation in Bacillus subtilis. Previous crystallographic studies had led to the conclusion that phosphorylation alters the binding affinity of SpoIIAA for its partner proteins solely through the additional charge and bulk of the phosphoryl group: small structural changes observed elsewhere in the protein were considere...

Adenosine 5'-[gamma(S)-16O,17O,18O]triphosphate has been used to determine the stereo-chemical course of phosphoryl transfer catalysed by rat liver glucokinase. The chirality of the product, D-glucose 6-[16O,17O,18O]phosphate was analysed by 31P n.m.r. spectroscopy. The reaction proceeds with inversion of configuration at phosphorus. The simplest interpretation of this result, which is the same...

The bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) includes a collection of proteins that accomplish phosphoryl transfer from phosphoenolpyruvate (PEP) to a sugar in the course of transport. The soluble proteins of the glucose transport pathway also function as regulators of diverse systems. The mechanism of interaction of the phosphoryl carrier proteins with each other as ...

Reaction 1 was observed in cell-free enzyme preparations of C. kluyveri (21), but the participation of the remaining reactions is supported only by indirect evidence obtained from studies on other bacteria (2). Koepsell et al. (12) demonstrated the formation of butyryl phosphate from acetyl phosphate and butyrate by cell-free extracts of Clostridium butylicum; and Lipmann (13, 14) demonstrated ...

The stem-loop-binding protein (SLBP) is involved in multiple aspects of histone mRNA metabolism. To characterize the modification status and sites of SLBP, we combined mass spectrometric bottom-up (analysis of peptides) and top-down (analysis of intact proteins) proteomic approaches. Drosophilia SLBP is heavily phosphorylated, containing up to seven phosphoryl groups. Accurate M(r) determinatio...