A comparison of the characteristics of two murine-toxic proteins from Pasteurella pestis

• Published in: Biochimica et biophysica acta Vol. 130; no. 2; pp. 406 - 419
• Main Authors: Montie, Thomas C., Montie, Diane B., Ajl, Samuel J.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 28.12.1966
• Subjects: Amino Acids - analysis; Animals; Bacterial Proteins - analysis; Catalase - analysis; Electrophoresis; Immunodiffusion; Injections, Intravenous; Mice; Molecular Weight; Pasteurella - analysis; Spectrophotometry; Toxins, Biological - analysis; Tryptophan - analysis; Ultracentrifugation
• DOI: 10.1016/0304-4165(66)90237-6
• ISSN: 0304-4165; 0006-3002

Two murine toxic proteins of relatively equivalent specific toxicity, previously isolated from an avirulent strain of Pasteurella pestis, have been further characterized. Molecular weights determined on Sephadex G-200 columns were 240 000 for Toxin A and 120 000 for Toxin B. Whereas this information, together with the sedimentation values, amino acid composition and ultraviolet spectra suggests a polymeric relationship between the two toxins, the 30% higher tryptophan content in Toxin A is not in accord with this notion. The selective inhibition of Toxin A formation in vivo on the addition of tryptophan analogues may be related to this difference in tryptophan content. Other differences include the increased lability of Toxin A and the high absorption of Toxin B in the 200 to 230 mμ ultraviolet range. These latter differences, along with the previously reported responses to -SH and other denaturing reagents, may be reflecting primarily differences in tertiary structure and amino acid sequences. Toxin B has been found to be identical with the earlier isolated plague murine toxin.