Chitinase, an enzyme important in the degradation of chitin, is produced by the EF-4a bacterium. Heavy concentrations of zinc were found to inhibit enzyme activity. This decrease in activity was more prominent with the harvested crude enzyme than with the purified dialysate. One reason for this difference could be that chitin chelates the zinc, inhibiting its degradation and decreasing substrate availability. Because of lower protein concentration in the dialysate, excess chitin is present. This excess chitin is degraded by chitinase and products of enzyme activity remain constant. Another reason for the difference could be that a dual enzyme system is present in the crude. One of these enzymes is capable of degrading chitin which is chelated to zinc while the other enzyme cannot. The dialysate may contain only the enzyme that does degrade chitin which is chelated to zinc, having been purified through affinity chromato,-raphychromatography. Therefore, the zinc does not interfere with degradation, and the chitin does react with the chitinase. Enzyme activity remains high and does not decline.