| Method |
P.1 right column bottom paragraph:"Here, [investigators] jointly address the rate–temperature dependencies of all enzyme classes, and compare them to the dependency of nonenzymatic reactions. [They] challenge the generally accepted paradigm that thermophilic, mesophilic, and psychrophilic enzymes have distinct rate–temperature dependencies, and that temperature–rate dependencies relate, by default, to enzyme dynamics. [They] suggest a common theme that underlines the temperature–rate dependency of all enzymes as long as they maintain their folded state. Also, [they] re-examine the generally assumed linkage between the overall rigidity of the fold and active site of an enzyme." |
| Comments |
P.4 right column 2nd paragraph:"[Investigators] also note that the loss of rate acceleration with temperature varies significantly between enzymes, and the L10 values (Box 1) range from ∼1 up to nearly 5. The variation, however, shows no correlation with the different classes. Rather, enzymes among the most proficient characterized so far, such as cytidine deaminase or orotidine 5′-monophosphate decarboxylase [ref 32], exhibit the largest loss factor (L10) values (Table S2 BNID 112398). This could be ascribed to these enzymes having the largest differences between the enzymatic and nonenzymatic activation energies. However, high rate enhancements and catalytic proficiencies (kcat/knon, kcat/KM/knon, respectively) are not correlated with low Q10enz values (Figure S1, Table S6)." P.5 left column 2nd paragraph:"That Q10 kcat is larger than Q10 kcat/KM also suggests that factors in addition to activation energy differences affect Q10enz and L10 values, as argued above. This is because kcat reports the enzyme-bound transitions state to a larger extent than kcat/KM. Moreover, if Q10enz and Q10non differ only because of activation energies, then Q10enz is expected to correlate with catalytic proficiency a measure of transition state stabilization. Although data are sparse, such correlation is clearly not observed (Figure S1, Table S6)." |