Localization and Disruption Kinetics of L-Asparaginase from E. caratovora Cells by High Power Ultrasound

S. D. Saptarshi and S. S. Lele

Abstract
High power ultrasound technique was adopted in our study to maximize the release of L-asparaginase from cells of E. caratovora. Duty cycle and acoustic power (total power delivered to sample) were found to be the key elements influencing the release of enzyme during this process. Maximum enzyme activity 82 IU mL–1 was obtained when cells of Erwinia were sonicated at 50 % duty cycle and 50 W acoustic power for 4 minutes. Subcellular enzyme location was estimated by calculating the rate of enzyme release to protein release (location factor) at varying magnitudes of duty cycle (10 %, 30 % and 50 %) and acoustic power (10 W, 30 W and 50 W) during the sonication cycle of 4 minutes. Magnitude of location factor obtained in all the varied conditions was found to be less than unity revealing the cytoplasmic location of enzyme. Furthermore, disruption kinetics was calculated by studying the effect of total power and duty cycle upon percent cell survival. Increased and efficient disruption was achieved at higher values of both duty cycle and acoustic power indicating a direct correlation between degree of disruption and these two independent variables. Magnitude of location factor and disruption constant (β) at 50 % duty cycle and 50 W acoustic power were found to be 0.92 and 0.120 min–1 respectively.

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Keywords
L-asparaginase, sonication, location factor, disruption kinetics