Assay of carbonic anhydrase by titration at constant pH

摘要: 1. A method is described for measuring accurately the initial velocity of hydration reaction catalysed by enzyme carbonic anhydrase (EC 4.2.1.1); depends on titration H+ ions at constant pH. 2. Human erythrocyte anhydrase, isoenzyme C, was used to illustrate method. Under experimental conditions employed (0°, pH7·0, in presence 45mm-sodium chloride and 5mm-sodium phosphate) C obeyed Michaelis equation over range substrate concentration 1–16mm-carbon dioxide. The kinetic constants found were: Km=8·2mm; V/[E0]=5·0×104 sec.−1.