45791-94-4Relevant academic research and scientific papers
Variation of Counterion Binding in Micelles of Cetyltrimethylammonium Hydroxide
Chalmovich, Hernan,Cuccovia, Iolanda M.,Bunton, Clifford A.,Moffatt, John R.
, p. 3584 - 3586 (1983)
Reaction of N-methyl-4-cyanopyridinium fluoroborate (1) with OH- in aqueous micelles of cetyltrimethylammonium hydroxide (CTAOH) occurs wholly in the aqueous pseudophase.Comparison of the rate constants in CTAOH and NaOH allows estimation of the concentrations of free and micellar bound OH-.The values of α, the fractional ionization of the micelles, decrease with increasing concentration of OH-, in agreement with evidence from reactions of substrates bound to micelles of CTAOH.
Characterization of nicotinamidases: Steady state kinetic parameters, classwide inhibition by nicotinaldehydes, and catalytic mechanism
French, Jarrod B.,Cen, Yana,Vrablik, Tracy L.,Xu, Ping,Allen, Eleanor,Hanna-Rose, Wendy,Sauve, Anthony A.
experimental part, p. 10421 - 10439 (2011/10/07)
Nicotinamidases are metabolic enzymes that hydrolyze nicotinamide to nicotinic acid. These enzymes are widely distributed across biology, with examples found encoded in the genomes of Mycobacteria, Archaea, Eubacteria, Protozoa, yeast, and invertebrates, but there are none found in mammals. Although recent structural work has improved our understanding of these enzymes, their catalytic mechanism is still not well understood. Recent data show that nicotinamidases are required for the growth and virulence of several pathogenic microbes. The enzymes of Saccharomyces cerevisiae, Drosophila melanogaster, and Caenorhabditis elegans regulate life span in their respective organisms, consistent with proposed roles in the regulation of NAD+ metabolism and organismal aging. In this work, the steady state kinetic parameters of nicotinamidase enzymes from C. elegans, Sa. cerevisiae, Streptococcus pneumoniae (a pathogen responsible for human pneumonia), Borrelia burgdorferi (the pathogen that causes Lyme disease), and Plasmodium falciparum (responsible for most human malaria) are reported. Nicotinamidases are generally efficient catalysts with steady state kcat values typically exceeding 1 s -1. The Km values for nicotinamide are low and in the range of 2 -110 μM. Nicotinaldehyde was determined to be a potent competitive inhibitor of these enzymes, binding in the low micromolar to low nanomolar range for all nicotinamidases tested. A variety of nicotinaldehyde derivatives were synthesized and evaluated as inhibitors in kinetic assays. Inhibitions are consistent with reaction of the universally conserved catalytic Cys on each enzyme with the aldehyde carbonyl carbon to form a thiohemiacetal complex that is stabilized by a conserved oxyanion hole. The S. pneumoniae nicotinamidase can catalyze exchange of 18O into the carboxy oxygens of nicotinic acid with H218O. The collected data, along with kinetic analysis of several mutants, allowed us to propose a catalytic mechanism that explains nicotinamidase and nicotinic acid 18O exchange chemistry for the S. pneumoniae enzyme involving key catalytic residues, a catalytic transition metal ion, and the intermediacy of a thioester intermediate.
Micellar Reaction of Hydrophilic Ions: A Coulombic Model
Bunton, Clifford A.,Moffatt, John R.
, p. 4166 - 4169 (2007/10/02)
Distribution of hydrophilic ions about a spherical micelle has been estimated by using the Poisson-Boltzmann equation for finite salt and surfactant concentrations.It is consistent with rate-surfactant profiles for reactions of p-nitrophenyl diphenyl phos
