<> "The repository administrator has not yet configured an RDF license."^^ . <> . . . "Effects of protonation on the hydrolysis of triphosphate in vacuum and the implications for catalysis by nucleotide hydrolyzing enzymes"^^ . "Background: Nucleoside triphosphate (NTP) hydrolysis is a key reaction in biology. It involves breaking two very stable bonds (one P–O bond and one O–H bond of water), in either a concurrent or a sequential way. Here, we systematically examine how protonation of the triphosphate affects the mechanism of hydrolysis. Results: The hydrolysis reaction of methyl triphosphate in vacuum is computed with protons in various numbers and position on the three phosphate groups. Protonation is seen to have a strong catalytic effect, with the reaction mechanism depending highly on the protonation pattern. Conclusion: This dependence is apparently complicated, but is shown to obey a well-defined set of rules: Protonation of the α- and β-phosphate groups favors a sequential hydrolysis mechanism, whereas γ-protonation favors a concurrent mechanism, the two effects competing with each other in cases of simultaneous protonation. The rate-limiting step is always the breakup of the water molecule while it attacks the γ-phosphorus, and its barrier is lowered by γ-protonation. This step has significantly lower barriers in the sequential reactions, because the dissociated γ-metaphosphate intermediate (PγO3 −) is a much better target for water attack than the un-dissociated γ-phosphate (−PγO4 2−). The simple chemical logic behind these rules helps to better understand the catalytic strategy used by NTPase enzymes, as illustrated here for the catalytic pocket of myosin. A set of rules was determined that describes how protonating the phosphate groups affects the hydrolysis mechanism of methyl triphosphate: Protonation of the α- and/or β- phosphate groups promotes a sequential mechanism in which P-O bond breaking precedes the breakup of the attacking water, whereas protonation of the γ-phosphate promotes a concurrent mechanism and lowers the rate-limiting barrier of water breakup. The role played by individual protein residues in the catalytic pocket of triphosphate hydrolysing enzymes can be assigned accordingly."^^ . "2016" . . "17" . "12" . . "BioMed Central; Springer"^^ . . . "BMC Biochemistry"^^ . . . "14712091" . . . . . . . . "Farooq Ahmad"^^ . "Kiani"^^ . "Farooq Ahmad Kiani"^^ . . "Stefan"^^ . "Fischer"^^ . "Stefan Fischer"^^ . . . . . . "Effects of protonation on the hydrolysis of triphosphate in vacuum and the implications for catalysis by nucleotide hydrolyzing enzymes (PDF)"^^ . . . "12858_2016_Article_68.pdf"^^ . . . "Effects of protonation on the hydrolysis of triphosphate in vacuum and the implications for catalysis by nucleotide hydrolyzing enzymes (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "Effects of protonation on the hydrolysis of triphosphate in vacuum and the implications for catalysis by nucleotide hydrolyzing enzymes (Other)"^^ . . . . . . "preview.jpg"^^ . . . "Effects of protonation on the hydrolysis of triphosphate in vacuum and the implications for catalysis by nucleotide hydrolyzing enzymes (Other)"^^ . . . . . . "medium.jpg"^^ . . . "Effects of protonation on the hydrolysis of triphosphate in vacuum and the implications for catalysis by nucleotide hydrolyzing enzymes (Other)"^^ . . . . . . "small.jpg"^^ . . . "Effects of protonation on the hydrolysis of triphosphate in vacuum and the implications for catalysis by nucleotide hydrolyzing enzymes (Other)"^^ . . . . . . "indexcodes.txt"^^ . . "HTML Summary of #22344 \n\nEffects of protonation on the hydrolysis of triphosphate in vacuum and the implications for catalysis by nucleotide hydrolyzing enzymes\n\n" . "text/html" . . . "540 Chemie"@de . "540 Chemistry and allied sciences"@en . . . "570 Biowissenschaften, Biologie"@de . "570 Life sciences"@en . .