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Endogenous protease-activated 66-kDa toxin from Bacillus thuringiensis subsp. kurstaki active against Spodoptera littoralis. FEMS Microbiol Lett 1998 Feb 01;159(1):113-20



Pubmed ID





The anti-lepidopteran toxin from sporulated Bacillus thuringiensis subsp. kurstaki cells, generated by the proteolytic action of endogenous protease(s) on the protoxin, was purified and studied to identify the effect of such proteolysis on the biochemical nature of the toxin. The active toxin was purified employing anion-exchange chromatography to absolute homogeneity, as indicated by SDS-PAGE and Western blotting. Antisera to the purified toxin (66 kDa) crossreacted with the protoxin (132 kDa) confirming its origin from protoxin. The purified toxin with a pI of 7.95 was derived from the N-terminal region of the protoxin (pI 7.6). Circular dichroism data revealed that the toxin has significant secondary structure and it undergoes pH dependent conformational change. Unlike the toxin generated by exogenous proteases such as trypsin, etc., the endogenous protease(s) activated toxin is highly lethal to a tolerant insect variety of the lepidopteran order, Spodoptera littoralis.

Author List

Kumar NS, Venkateswerlu G


Suresh Kumar PhD Associate Professor in the Pathology department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Amino Acids
Bacillus thuringiensis
Bacterial Toxins
Biological Assay
Blotting, Western
Circular Dichroism
Hydrogen-Ion Concentration
Protein Precursors
Protein Structure, Secondary
Species Specificity
jenkins-FCD Prod-482 91ad8a360b6da540234915ea01ff80e38bfdb40a