Isolation, Purification And Identification With Bio-mass Spectrometric Technique For Ricin And Abrin Toxin

Ricin and abrin, which are a kind of plant toxin, are a heterodimeric glycoprotein composed of a toxic A-chain and a galactose-specific lectin B-chain via a disulfide bind. Ricin and abrin toxin all belong to the type II ribosome-inactivating proteins family (RIPII) whose members disrupt ribosomal architecture and therefore stop protein synthesis. The A-chain could be linked to antibodies to form immunotoxins, combining the targeting ability of antibodies with the acute toxicity of the A-chain. This property promotes ricin and abrin as potential candidates for cancer treatment. And much work remains to be done to find possible uses of these conjugates in drug discovery and clinical trial.On the other hand, ricin or abrin has been used as an threat agent in terrorism because these two toxins have high toxicity and stability and the techniques to prepare them can be publicly obtained. So the United States Centers for Disease Control (CDC) lists ricin and abrin on its second highest priority list as a biological agent. In fact, the need to analysis and characterize these protein toxins is a substantial challenge. Therefore, whether for the application in therapeutic agent, clinical diagnosis or for medical defense the rapid and sensitive methods for separating and identifying ricin or abrin are needed.In the present thesis, ricin and abrin toxins have been isolated and purified by the optimized conventional methods, a new analysis method to identify ricin and abrin with bio-mass technique has been developed. This thesis includes three sections. In the first section the extraction and purification of ricin toxin has been carried out. Based on the specific ability of ricin to bind galactose, an affinity column modified with galactose residues was used to remove a large quantity of impurity proteins not b inding to the...