TY - JOUR
T1 - Comparative studies on kinetics of inhibition of protein synthesis in intact cells by ricin and a conjugate of ricin B-chain with momordin
AU - Sharma, Shalini
AU - Podder, Sunil K.
AU - Karande, Anjali A.
N1 - Funding Information:
This work was supported by a grant to SKP from Council for Scientific and Industrial Research, Government of India. We would also like to thank Dr Sritulasi for helpful suggestions.
PY - 1999
Y1 - 1999
N2 - 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.
AB - 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.
KW - Momordin
KW - Ribosome inactivating proteins (RIPs)
KW - Ricin
KW - Ricin A-chain
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U2 - 10.1023/A:1007043218769
DO - 10.1023/A:1007043218769
M3 - Article
C2 - 10569193
AN - SCOPUS:0032882685
SN - 0300-8177
VL - 200
SP - 133
EP - 141
JO - Molecular and Cellular Biochemistry
JF - Molecular and Cellular Biochemistry
IS - 1-2
ER -