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All reactions are accelerated by an increase in temperature, but the magnitude of that effect on very slow reactions does not seem to have been fully appreciated. The hydrolysis of polysaccharides, for example, is accelerated 190,000-fold when the temperature is raised from 25 to 100[degrees]C, while the rate of hydrolysis of phosphate monoester dianions increases 10,300,000-fold. Moreover, the slowest reactions tend to be the most heat-sensitive. These tendencies collapse, by as many as five orders of magnitude, the time that would have been required for early chemical evolution in a warm environment. We propose, further, that if the catalytic effect of a 'proto-enzyme'--like that of modern enzymes--were mainly enthalpic, then the resulting rate enhancement would have increased automatically as the environment became cooler. Several powerful nonenzymatic catalysts of very slow biological reactions, notably pyridoxal phosphate and the ceric ion, are shown to meet that criterion. Taken together, these findings greatly reduce the time that would have been required for early chemical evolution, countering the view that not enough time has passed for life to have evolved to its present level of complexity. activation energy | thermophilic organisms | pyridoxal phosphate | phosphate ester hydrolysis | amino acid decarboxylation doi/ 10.1073/pnas.1013647107

Author(s): Randy B. Stockbridge [1]; Ludmila Kolmakova-Partensky [1]; Tania Shane [1]; Akiko Koide [2]; Shohei Koide [2]; Christopher Miller [1, 3]; Simon Newstead (corresponding author) [4] To contend with hazards [...]

The tetrabutylammonium salt of neopentyl phosphate has entered wet cyclohexane at concentrations sufficient to allow determination of its rate of hydrolysis. The second-order rate constant for hydrolysis of the phosphomonoester dianion is increased by transfer from water to cyclohexane.