Comparative structural and functional studies of avian and mammalian hemoglobins.

Abstract

Thermal stabilities of chicken, grey lag goose (Anser anser), turkey as avian hemoglobins (Hbs); and human, bovine, sheep and horse as mammalian Hbs in hemolysate form were investigated and compared with oxygen affinities taken from literature. The thermal stability was obtained from thermal profiles using temperature scanning spectrophotometry. The buffer conditions were 50 mM Tris, pH 7.2, and 1 mM EDTA. The average of the inverse temperature transitions, average hydrophobicity, total van der Waals volume, partial molal volume and hydration potential were calculated by computational methods. The hemolysed avian Hbs have a lower oxygen affinity, higher thermal stability and higher self association than the mammalian Hbs. These observations are based on amino-acid composition, influence of ionic effectors, and the presence of Hb D in several avian Hbs. The results indicate that the avian Hbs have a more tense (T) conformation than the mammalian Hbs.

Comparison of three different inhalant anesthetic agents (isoflurane, sevoflurane, desflurane) in red-tailed hawks (Buteo jamaicensis)

“…Schmitt et al suggest that the clinical use of a commercial pulse oximeter for anesthetic monitoring of birds is unsatisfactory due to the poor accuracy of saturation readings. Differences in avian hemoglobin versus mammalian hemoglobin have been well documented in the literature (Schmitt et al 1998;Powell 2000;Ajloo et al 2002). Low SpO 2 values obtained in the current study were thought to be related to sensor artefact as no detectable adverse effects in these hawks were noted during or after the anesthetic episode but could also be due to the aspiration of air if the birds breathed around the uncuffed tube.…”

“…Differences in avian hemoglobin versus mammalian hemoglobin have been well documented in the literature (Schmitt et al. 1998; Powell 2000; Ajloo et al. 2002).…”

Improving Luminol Blood Detection in Forensics

“…Using a higher temperature in conjunction with a protein chemical denaturant in MD simulations was shown not to affect the results as long as the temperature is constrained below the protein's melting point T m . For human Hb, a temperature of 55°C is well below this value (63°C ). The temperature was kept constant by coupling to a Nosé‐Hoover thermostat and the pressure was constrained at 1 atm using the Parrinello–Rahman barostat .…”

Purification, crystallization, preliminary X-ray diffraction and molecular-replacement studies of great cormorant (Phalacrocorax carbo) haemoglobin

“…The ability of birds to maintain an efficient oxygen supply to the brain during severe hypoxia is an important adaptation contributing to their exceptional tolerance of extreme altitudes. Compared with mammalian Hb, the presence of hydrophobic residues is increased in avian Hb, which leads to its higher thermal stability and consistent attainment of the tense (T) state (Ajloo et al, 2002). The conservation of hydrophobic domains in avian Hbs might in fact have been required for the stabilization of tertiary structure in order to maintain the function of the protein through a long period of evolution (Perutz, 1983).…”