title: Extraordinary stability of hemocyanins from L. polyphemus and E. californicum studied using infrared spectroscopy from 294 to 20 K.
abstract: Hemocyanins are large oligomeric respiratory proteins found in many arthropods and molluscs. Here we give infrared spectroscopic evidence of a high stability towards exposure to sub-zero temperatures for hemocyanins from the arthropods Limulus polyphemus and Eurypelma californicum at different pH values. Small but distinct temperature induced changes of the secondary structure were observed, but a stable core of at least 40% α-helical structure is preserved as identified in the infrared spectra obtained between 294 and 20 K. The structural changes differ in detail somewhat for the two hemocyanins, with overall fewer changes observed in the case of E. californicum. Notably, in both cases the overall changes in the α-helical content are found to be fully reversible. The small changes in the secondary structure and reversibility upon cold treatment seem to be a particular property of the two hemocyanins, since it was not observed for myoglobin studied in the same way.
authors.affiliation: Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140 Université de Strasbourg CNRS, 1 Rue Blaise Pascal 67070, France. hellwig@unistra.fr.
authors.forename: Mireille
authors.initials: M
authors.lastname: Khalil
authors.affiliation: Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140 Université de Strasbourg CNRS, 1 Rue Blaise Pascal 67070, France. hellwig@unistra.fr.
authors.forename: Zahia
authors.initials: Z
authors.lastname: Boubegtiten-Fezoua
authors.affiliation: Institute for Molecular Biophysics, University of Mainz, Jakob-Welder-Weg 26, 55128 Mainz, Germany. nhellmann@uni-mainz.de.
authors.forename: Nadja
authors.initials: N
authors.lastname: Hellmann
authors.affiliation: Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140 Université de Strasbourg CNRS, 1 Rue Blaise Pascal 67070, France. hellwig@unistra.fr.
authors.forename: Petra
authors.initials: P
authors.lastname: Hellwig
mesh_terms: D000818:Animals; D060829:Arthropod Proteins / Q000737:chemistry*; D006433:Hemocyanins / Q000737:chemistry*; D006737:Horseshoe Crabs; D017433:Protein Structure, Secondary; D013055:Spectrophotometry, Infrared; D013112:Spiders
chemical_list: D060829:Arthropod Proteins; D006433:Hemocyanins