Comparative studies on kinetics of inhibition of protein synthesis in intact cells by ricin and a conjugate of ricin B-chain with momordin

Sharma, Shalini and Podder, Sunil K and Karande, Anjali A (1999) Comparative studies on kinetics of inhibition of protein synthesis in intact cells by ricin and a conjugate of ricin B-chain with momordin. In: Molecular and Cellular Biochemistry, 200 (1-2). pp. 133-141.

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Abstract

Ribosome inactivating proteins from plants have been widely used for the preparation of immunotoxins and hormonotoxins, which have potential application in the therapy of diseases such as cancer. However, these hybrid toxins have been found to be less cytotoxic than native ribosome inactivating proteins. Therefore, it is important to understand the factors that control the intrinsic toxicity of RIPs and the hybrid toxins prepared using them. Here, a hybrid toxin has been prepared by coupling ricin B-chain to momordin and the cytotoxicity of this hybrid toxin has been compared to that observed in case of native ricin. In the two cell types used here, thymocytes and macrophages, the conjugate was found to be about 40 fold less toxic than native ricin. Kinetics of inhibition of protein synthesis showed that prior to onset of inhibition the conjugate exhibits a longer lag phase than native ricin. The rates of inhibition of protein synthesis by the conjugate were also found to be slower than ricin. Analysis of the results suggests that in addition to cell surface binding, the B-chain of ricin facilitates another step in the transmembrane translocation of ricin A-chain to the cytosol.

Item Type:	Journal Article
Publication:	Molecular and Cellular Biochemistry
Publisher:	Kluwer Academic Publishers
Additional Information:	The copyright belongs to Kluwer Academic Publishers.
Keywords:	ribosome inactivating properties (RIPs);ricin;ricin A-chain;momordin
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	28 Sep 2007
Last Modified:	19 Sep 2010 04:39
URI:	http://eprints.iisc.ac.in/id/eprint/11954

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