Glycogen phosphorylase has been isolated from rabbit muscle in two different molecular forms, phosphorylase a, a tetramer with a molecular weight of 495,000 (2-4), and phosphorylase b, a dimer with a molecular weight of 242,000 (3-5). The dimerization of the protein that occurs in the conversion of phosphorylase 6 to a with phosphorylase kinase, Mg++, and ATP has been found to result from the i...

We have probed the electrostatic environment of the active site of the Tetrahymena group I ribozyme (E) using protonated 2'-aminoguanosine (), in which the 2'-OH of the guanosine nucleophile (G) is replaced by an group. At low concentrations of divalent metal ion (2 mM Mg(2+)), binds at least 200-fold stronger than G or G(NH)()2, with a dissociation constant of </=1 microM from the ribozyme. ol...

This account outlines the results obtained in the author’s laboratory on the asymmetric cyclopropanation of enantiopure 1-phosphorylvinyl p-tolyl sulfoxides with sulfur ylides and diazoalkanes. Based on experimental results and theoretical calculations, the transition-state model for asymmetric cyclopropanation is proposed. A great synthetic value of the reaction investigated is exemplified by ...

Equilibration of the phosphorus in radioactive phosphoric acid with the phosphorus in phosphorus oxychloride occurs if these compounds are refluxed together for approximately 24 h. This observation led us to develop a method for the preparation of radioactive phosphorus oxychloride on a small scale with high specific radioactivity. The labeled phosphorus oxychloride may be utilized directly in ...

2- Ethoxy-4(3H) quinazolinone 1 was synthesized and allowed to react with various halides, namely: alkyl, benzyl, allyl, acyl, haloacetyl, crotonyl, benzoyl, 2-furoyl and 1-naphthalenesulphonyl halides affording quinazoline and quinazolinone derivatives. The reactions of compound 1 with phosphorus oxychloride, phosphorus pentasulfide, ethyl chloroformate, ethyl chloroacetate, ?-bromoglucose tet...

The active site of the cAMP-dependent protein kinase catalytic subunit harbors a cluster of acidic residues-Asp 127, Glu 170, Glu 203, Glu 230, and Asp 241-that are not conserved throughout the protein kinase family. Based on crystal structures of the catalytic subunit, these amino acids are removed from the site of phosphoryl transfer and are implicated in substrate recognition. Glu 230, the m...

Activated Lactococcus lactis beta-phosphoglucomutase (betaPGM) catalyzes the conversion of beta-d-glucose 1-phosphate (betaG1P) derived from maltose to beta-d-glucose 6-phosphate (G6P). Activation requires Mg(2+) binding and phosphorylation of the active site residue Asp8. Initial velocity techniques were used to define the steady-state kinetic constants k(cat) = 177 +/- 9 s(-)(1), K(m) = 49 +/...

We have previously shown that the lipooligosaccharide (LOS) from Neisseria meningitidis and N. gonorrhoeae engages the TLR4-MD-2 complex. In this study, we report that LOS from different meningococcal and gonococcal strains have different potencies to activate NF-κB through TLR4-MD-2 and that the relative activation can be correlated with ion abundances in MALDI-TOF mass spectrometry that are i...

Despite the biological and medical importance of signal transduction via Ras proteins and despite considerable kinetic and structural studies of wild-type and mutant Ras proteins, the mechanism of Ras-catalyzed GTP hydrolysis remains controversial. We take a different approach to this problem: the uncatalyzed hydrolysis of GTP is analyzed, and the understanding derived is applied to the Ras-cat...