Similarity of protein conformation at low pH and high temperature observed for B - chains of two plant toxins: ricin and mistletoe lectin I

Journal/Book: FEBS Letters 229 (1), 119-122. 1988;

Abstract: A comparative study of subunits of two plant toxins, ricin (RC) andmistletoe lectin 1 (ML 1), has been undertaken. The study suggests thatisolated B-chains of these toxins undergo structural transitions at lowpH (from 5 to 4) and high temperature (45 degrees C), and as a result ofthe guanidine hydrochloride denaturing effect (to 3 M). Our resultsindicate that the protein conformation observed at low pH and hightemperature are similar, though not identical. These conformationsdiffer from the native one (pH 7, 25 degrees C), the protein in theseconformations has a low fluorescence tryptophan intensity, andtryptophans are more exposed to aqueous solutions. However, theseconformations differ also from the state unfolded by guanidinehydrochloride. An assumption is made that the partially denaturedprotein structure, exhibited at low pH and high temperature, is afunctionally essential intermediate state of the toxin B-chain. Author.

Keyword(s): COMPARATIVE-STUDY

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