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Thermostabilization, Expression, Purification, and Crystallization of the Human Serotonin Transporter Bound to S-citalopram
Published on: November 27, 2016
Expression and purification of cysteine introduced recombinant saporin
Emine Günhan1, Mimi Swe, Mine Palazoglu
1Department of Neurobiology, Physiology, and Behavior, University of California, One Shields Avenue, 196 Briggs Hall, Davis, CA 95616, USA. egunhan@ucdavis.edu
Abstract:
Saporin, a ribosome inactivating protein is widely used for immunotoxin construction. Here we describe a mutation of saporin (sap)-3 DNA by introducing a cysteine residue, followed by protein expression and purification by ion exchange chromatography. The purified Cys255sap-3, sap-3 isomer and commercially purchased saporin, were tested for toxicity using assays measuring inhibition for protein synthesis. The IC(50) values showed that the toxicity of the Cys255sap-3 is equivalent to the sap-3 isomer and commercial saporin. Reactivity of Cys255sap-3 was confirmed by labeling with a thio-specific fluorescent probe as well as conjugation with a nonspecific mouse IgG. We have found that a single cysteine within saporin provides a method for antibody conjugation that ensures a uniform and reproducible modification of a saporin variant retaining high activity.
