Enzymes Are Powerful Enzymes accelerate reactions by factors of as much as a million or more. TABLE 8.I Rate enhancement by selected enzymes Nonenzymatic Uncatalyzed rate Catalyzed rate Rate enhancement Enzyme half-life (kun-) (kat) (kcatS-/kunS-l） OMP decarboxylase 78,000,000 years 2.8X10-16 39 1.4×107 Staphylococcal nuclease 130,000 years 1.7X10-13 95 5.6X1014 AMP nucleosidase 69,000 years 1.0×10-11 60 6.0×1012 Carboxypeptidase A 7.3 years 3.0X109 578 1.9X1011 Ketosteroid isomerase 1 weeks 1.7×10-7 66,000 3.9X101 Triose phosphate isomerase 1.9 days 4.3X106 4,300 1.0X109 Chorismate mutase 7.4 hours 2.6X10-5 50 1.9X105 Carbonic anhydrase 5 seconds 1.3×101 1×105 7.7X105 Abbreviations:OMP,orotidine monophosphate;AMP,adenosine monophosphate. Source:After A.Radzicka and R.Wofenden.Science 267(1995):90-93. Indeed,most reactions in biological systems do not take place at perceptible rates in the absence of enzymes.Enzymes Are Powerful Enzymes accelerate reactions by factors of as much as a million or more. Indeed, most reactions in biological systems do not take place at perceptible rates in the absence of enzymes