Carboxylesterase aus Schweinenierenmikrosomen, I. Isolierung, Eigenschaften und Substratspezifität

Abstract

A carboxylesterase (EC 3.1.1.1) was isolated from pig kidney microsomes. The enzyme was purified 65-fold with a yield of 25%. The enzyme preparation was electrophoretically pure on paper and in starch gel. Pig kidney esterase and pig liver esterase had the same mobility in electro-phoresis. The molecular weight was 163,000 calculated from gel filtration and ultracentrifugation. The enzyme was homogeneous in the ultracentrifugate. An equivalent weight of 80,100 was determined from the reaction with E 600. Thus one molecule of pig kidney esterase possesses 2 active centres. The kidney enzyme described here catalyzes the hydrolysis both of carboxyl esters and certain aromatic acid amides (acetanilide, phenacetin and others), and in this respect it resembles the pig liver esterase. The pig kidney esterase and the pig liver esterase closely resemble each other in their pH-optimum and also in their behavior towards inhibitors. On the other hand there were some differences so that it is not certain that they are identical.