Studies on the Purification of Chitin Synthase from Coprinus cinereus

Abstract

Chitin synthase has been characterized from the stipes of Coprinus cinereus by a number of techniques. In the absence of digitonin, on gel filtration columns and during electrophoresis the enzyme showed properties consistent with having molecular weights from 1.5 105 to several million, suggesting its reversible aggregation into large multimolecular units. Gel chromatography in buffers containing digitonin gave highly reproducible results, and when followed by anion-exchange chromatography gave preparations with very high activity [e.g. 3.4 mol substrate incorporated min-1 (mg protein)-1] and apparent molecular weight 8.0 105. The best purification (140-fold) was achieved by gel chromatography followed by copper chelate affinity chromatography, giving a nearly pure enzyme preparation of activity 4.7 mol substrate incorporated min-1 (mg protein)-1, which showed only one band of molecular weight 6.7 104 on SDS-polyacrylamide electrophoresis. These purified preparations were free of the nucleoside diphosphatase and protease activities that were present in the early stages of purification.