2015/12/08 by P. Nissen, Per Nissen, Nissen, Per · 1 citation
Biochemistry, Genetics and Molecular Biology · Chemistry · Physics and Astronomy · #Biochemical Acid Research Studies #Biomolecules (q-bio.BM) #Chemical Physics (physics.chem-ph) #Chemical Reaction Mechanisms #FOS: Biological sciences #FOS: Physical sciences #Metabolism and Genetic Disorders #physics.chem-ph #q-bio.BM
paper · pdf · doi:10.48550/arxiv.1512.02561
Resubmission of 1418179, 8 pages, 3 figures, 1 table
arxiv created 2015/12/08 · openalex publication_date 2015/12/08 · arxiv updated 2015/12/09 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Reanalysis of data (Bruice and York 1961) for the pH dependences of the calculated apparent second-order rate constants (k2) for the reaction of tris-(hydroxymethyl)-aminomethane (TRIS) with phenyl esters reveals that the pH profiles are consistently much better represented as multiphasic, i.e. as a series of straight lines separated by discontinuities in the form of sharp breaks or noncontiguities (jumps), than by the continuous function used by the authors. For p-nitrophenyl acetate, m-nitrophenyl acetate, p-chlorophenyl acetate and phenyl acetate, the profiles are best represented as multiphasic in plots of log k2 vs. pH, whereas the profile for p-methylphenyl acetate is only multiphasic in a plot of k2 vs. pH. Data for the pseudo-first-order rate constants (kobs) give multiphasic pH profiles with patterns identical or very similar to those for k2. Extensive reanalyses of data for a wide variety of enzymatic and non-enzymatic reactions show, similarly, that pH profiles are in general better represented as multiphasic than as curvilinear.