Purification and partial characterization of chitinases from sorghum seeds

Sorghum seeds contain multiple chitinases three of which have been purified by ammonium sulphate fractionation, chitin affinity chromatography and CM- cellulose cation exchange chromatography. The three chitinases, CH1, CH2 an d CH3 have apparent molecular masses of 24, 28 and 33 kDa, respectively, as determined by SDS-polyacrylamide gel electrophoresis. They differ in their electrophoretic mobility, exhibit chitinase activity, and react positively with polyclonal antibodies raised against bean and barley chitinases. All three chitinases have pH optima in the range of 4-6.5 and optimum temperatu res ranged from 37 to 40 degrees C. CH2 is found to have strong affinity fo r chitin and CH1 and CH3 have a lower affinity for chitin. All three chitin ases are inhibitory to the growth of Trichoderma viride and Fusarium monili forme. The seed-associated chitinases appear to be different from those ind uced in mature plants upon exposure to a variety of stresses suggesting dif ferences in biological functions between these two groups of chitinases. (C ) 1999 Elsevier Science Ireland Ltd. All rights reserved.