STRUCTURAL AND KINETIC CHARACTERIZATION OF MYOGLOBINS FROM EURYTHERMAL AND

• Main Authors: Peter William Madden, Stenothermal Fish Species, William Madden
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2003
• Subjects: Antarctic; The Antarctic; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.514.3293; http://www.library.umaine.edu/theses/pdf/MaddenPW2003.pdf

Teleost myoglobin (Mb) proteins from four fish species inhabiting different temperature environments were used to investigate the relationship between protein function and thermal stability. Mb was isolated from yellowfin tuna (homeothermal warm), mackerel (eurythermal warm), and the Antarctic teleost Notothenia coriiceps (stenothermal cold). Zebrafish (stenothermal tropical) myoglobin was expressed from cloned cDNA. N. coriiceps Mb cDNA has also been cloned, expressed at 20°C, and isolated from E. coli, but was not used in any of the functional and kinetic studies. These proteins differed in oxygen affinity, as measured by Oz dissociation rates and PS0 values, and thermal stability as measured by autooxidation rates. Mackerel Mb had the highest Pso value at 25OC (3.7mm Hg), corresponding to the lowest Oz affinity, followed by zebrafish ( I.Omm Hg), yellowfin tuna (1.Omm Hg), and N coriiceps (0.6mm Hg). Oxygen dissociation rates and Arrhenius plots were similar between all teleost species in this study, with the exception of mackerel myoglobin, which was two fold faster at all temperatures tested. Myoglobin from the Antarctic teleost had the highest autooxidation rate (0.44 h"), followed by mackerel (0.26 h-I), zebrafish (0.22 h-'), and yellowfin tuna