The Ambiguity of the Viscometric Method for the Deter-Mination of Dextranase Activity

Abstract

In earlier studies it was found that the tissue pellets of Avena seedlings decrease the viscosity of dextran solutions. By the use of direct methods for investigating the breakage of these molecules, it is shown that the lowering of viscosity of dextran solutions under the influence of tissue pellets of Avena coleoptiles is not due to an intramolecular process of molecular breakage (dextranase-like activity) but rather to an intermolecular process of still unknown nature. This conclusion is supported by the finding that solutions of entirely different macromolecules than dextrans are also affected by the tissue pellets. The observed changes in viscosity can therefore not be due to dextranase activity and the viscometric method for the determination of this activity is clearly ambiguous.

Key Words:

• viscosity
• dextranase activity
• Avena coleoptiles
• dextrans