African cassava mosaic virus has caused an immersed low yield of the cassava crop. The virus impacts stress on the cellular metabolism of the plant producing a lot of reactive oxygen species and increases the expression of the antioxidant enzymes. The activity of catalase as a response to oxidative stress was investigated in this research. Cassava leaf extract infected with the African cassava mosaic virus and uninfected were prepared and used as crude catalase extract. The total protein was determined by Biuret method and activity of the crude catalase was compared using hydrogen peroxide as substrate. Infected leaf extract had 141.02 ± 3.536 mg/mL protein, apparent Michealis constant (Kmapp) of 26.7 µM and maximum rate of reaction (Vmax) of 54.50 µM/min compared to the uninfected leaf extract with 75.04 ± 0.560 mg/mL protein, Kmapp of 39.61 µM and Vmax of 143.06 µM/min. The activation energy of the infected extract was 0.1578 J/mol compared to 0.2181 J/mol obtained for the uninfected extract. Activity of the crude catalase in the viral infected leaf extract from the study was higher than that in the uninfected one and confirms the response to the stressful condition imposed by the viral infection.
Key words: Cassava leaf extract, African cassava mosaic virus (ACMV), reactive oxygen species (ROS), catalase, hydrogen peroxide, Kmapp, Vmax.
CBSD, Cassava brown streak disease; ACMV, African cassava mosaic virus; ROS, reactive oxygen species; H2O2, hydrogen peroxide; BSA, bovine serum albumin.
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