kcat:The turnover number of an enzyme酶转换数 the number of substrate molecules converted into product by an enzyme molecule in a unit time when the enzyme is fully saturated with substrate(equal to the rate constant k,). 在饱和底物浓度下，单个酶单位时间内能转化底物的数目 TABLE 8.5 Turnover numbers of some enzymes Turnover number Enzyme (per second) Carbonic anhydrase 600,000 3-Ketosteroid 280,000 isomerase 1to104/s Acetylcholinesterase 25,000 Penicillinase 2,000 Lactate 1,000 dehydrogenase Chymotrypsin 100 DNA polymerase I 15 Tryptophan synthetase 2 Lysozyme 0.51 to 104 /s kcat: The turnover number of an enzyme 酶转换数 the number of substrate molecules converted into product by an enzyme molecule in a unit time when the enzyme is fully saturated with substrate (equal to the rate constant k2). 在饱和底物浓度下，单个酶单位时间内能转化底物的数目