Division of Nematology, Indian Agricultural Research Institute, New Delhi-110012.
1 Part of Ph. D. thesis submitted by the senior author to P.G. School, I.A.R.I., New Delhi in 1979.
Partially purified enzyme preparations of polyphenol oxidase from nematode-inoculated susceptible (Pusa Ruby) and resistant (SL-120) tomato varieties were subjected to the enzyme-characterization studies. The results revealed that polyphenol oxidase components from all the samples were heat stable and denatured after an exposure of the enzyme to 40°C for half an hour. The enzyme remained active at wide range of pH(3–8) with 2–3 pH optima. The enzyme from resistant variety was found to be more stable as compared to that of susceptible variety. It was apparent from this investigation that mercaptoethanol, sodium bisulphite, glutathione, sodium azide and certain phenolic acids were found to be strong inhibitors of enzyme. The conclusive evidences showed the differences in the enzyme characters for Pusa Ruby and SL-120, which indicate that the enzyme components of susceptible variety were different from that of resistant variety.
