Table 8.1: Rate enhancement by selected enzymes

Enzyme

Nonenzymatic

half-life

Uncatalyzed

rate (kun s−1)

Catalyzed

rate (kcat s−1)

Rate

enhancement

(kcat s−1/kun s−1)

OMP decarboxylase

78,000,000      years

2.8 × 10−16

        39

1.4 × 1017

Staphylococcal nuclease

130,000      years

1.7 × 10−13

        95

5.6 × 1014

AMP nucleosidase

69,000      years

1.0 × 10−11

        60

6.0 × 1012

Carboxypeptidase A

          7.3    years

3.0 × 10−9

      578

1.9 × 1011

Ketosteroid isomerase

          7      weeks

1.7 × 10−7

66,000

3.9 × 1011

Triose phosphate isomerase

        1.9      days

4.3 × 10−6

  4,300

1.0 × 109

Chorismate mutase

          7.4    hours

2.6 × 10−5

        50

1.9 × 106

Carbonic anhydrase

          5   seconds

1.3 × 10−1

              1 × 106

7.7 × 106

Abbreviations: OMP, orotidine monophosphate; AMP, adenosine monophosphate.

Source: After A. Radzicka and R. Wolfenden. Science 267:90–93, 1995.