Kinetic parameters of the interaction of the toxic lectins abrin and ricin with human erythrocytes and HeLa cells have been measured. The binding of 125I-labeled abrin and ricin to human erythrocytes and to HeLa cells at 37 degrees was maximal around pH 7, whereas at 0 degrees the binding was similar over a broad pH range. The binding occurred at similar rates at 0 degrees and 37 degrees with r...

The kinetics of protein synthesis inhibition in a cell-free system from rabbit reticulocyte lysate was studied after addition of abrin and ricin and the isolated A chains. The toxin A chains inhibited protein synthesis at a rate proportional to the amount added. When intact toxins were added to the reticulocyte lysate, the kinetics of protein synthesis inhibition indicated that the A chains mus...

Abrin is a toxic protein found in the jequirity seed. L-Abrine (N-methyl-tryptophan) is also found in the jequirity seed and can be used as a biomarker for abrin exposure. Analysis of L-abrine was added to an existing method for quantifying ricinine as a marker for ricin exposure in human urine and analytically validated. Accuracy and reproducibility were enhanced by including a newly synthesiz...

Trichosanthes kirilowii lectin 1 (TKL-1) isolated from the tuber of T. kirilowii consists of two chains, each with a molecular weight of about 30 kDa. It has immunological properties which are similar to some ribosome-inactivating proteins (RIPs). TKL-1 was crystallized in space group P2(1)2(1)2(1) and diffraction data were collected to 2.7 A resolution. The molecular-replacement method was app...

We have studied on the mechanism of ricin action on rat liver ribosomes and present evidence which shows that the toxin inactivates ribosomes by modifying two bases at positions G-4323 and A-4324 of 28S rRNA adjacent to alpha-sarcin cleavage site. Further results showing that those phosphodiester bonds are very labile against alkaline digestion and aniline-treatment strongly suggest that these ...

Three lectins have been isolated from an extract of mistletoe (Viscum album) by affinity chromatography on partially hydrolysed Sepharose and human immunoglobulin- Sepharose. The lectins differ in molecular weight and sugar specificity (lectin I, mol.wt. 11500, D-galactose-specific; lectin II, mol.wt. 60000, both D-galactose- and N-acetyl-D-galactosamine-specific; lectin III, mol. wt. 50000, N-...