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. 1984 Apr;45(4):721–724. doi: 10.1016/S0006-3495(84)84214-9

Effect of methylamine and plasmin on the conformation of human alpha 2-macroglobulin as revealed by differential scanning calorimetric analysis.

H S Cummings, S V Pizzo, D K Strickland, F J Castellino
PMCID: PMC1434896  PMID: 6202335

Abstract

Differential scanning calorimetric analysis was used as a probe of the conformational alteration in human alpha 2-macroglobulin (AM) upon its complex formation with methylamine and with the protease, human plasmin. The slow electrophoretic form of AM displayed a single thermal transition, characterized by a temperature midpoint (Tm) of 65.8 +/- 0.3 degrees, a calorimetric enthalpy (delta Hc) of 2,550 +/- 150 kcal/mol and a van't Hoff enthalpy (delta Hvh) of 140 kcal/mol. In the presence of sufficient methylamine to irreversibly disrupt the four thiol ester bonds in AM, a single thermal transition was obtained, characterized by a Tm of 62.8 +/- 0.3 degrees, a delta Hc of 1,700 +/- 100 kcal/mol, and a delta Hvh of 169 kcal/mol. These data suggest that a major conformational alteration is produced in AM upon complex formation with methylamine. When plasmin interacts with AM, the resulting thermogram displays Tm values for AM of 68-69 degrees and 77 degrees, also suggestive of a large conformational alteration in AM. However, this latter alteration appears dissimilar to the change induced by methylamine.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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