Structural characterization of a low solubility protein produced by Clostridium botulinum type G

J.A. GIMÉNEZ; O. CASCONE; M.J. BISCOGLIO DE JIMÉNEZ BONINO; A.C. PALADINI

Zentralblatt für Bakteriologie, Mikrobiologie und Hygiene

Fischer

Año: 1986 vol. 262 p. 179 - 188

0176-6724

A_ preliminary study of a low-toxicity protein, called cryoprotein, produced by Clostridium botulinum tvpe G, led to a better characterízation of the substance and to discriminate its relationship with type G botulinum toxin. This sparingly soluble protein has been characterized as an aggregared form of a soluble precursor with a MW 170000. This phenomenon is temperature-dependent. The monomeric protein is usually contaminated with a lower M, form (150000) quite probably originated by a limited proteolytic process. The amino acid composition of this protein is relatively analogous to that of the botulinum toxins A and B, the only notable exception being the absence of cysteine. The N-terminal amino acid is alanine and the C-terminal sequence is Val-Ala-Leu-OH. The low toxicity which is usually demonstrable in samples of this protein disappears after a reductive treatment, strongly suggesting that it is not an intrinsic property. Taking into account that some of its physicochemical properties are similar to those of the known botulinal toxins, it is quite probable that this substance accompanies G toxin preparations currently obtained by routine methods, increasing its non-toxic antigenic mass. This fact could be critical to the sensitivity and specificity of G toxin immunological detection methods.