Abstract:
Avian hemoglobin has unique oxygen transport characteristics. The homology model of minor hemoglobin component D (HbD) of Ring Necked Pheasant (Phasianus colchicus) was predicted using the three dimensional (3D) coordinates of chicken HbD as a template. The model was built with the help of MODELLEL (9v6) and its stereochemistry was evaluated with ProSa and PROCHECK. In present study we have analyzed the correlation of oxygen affinity of the predicted model and its structural changes with its ability to adapt, enabling it to live in its natural environment. In Phasianus colchicus Gln αD38 is unable to form a hydrogen bond with His β97 or Asp β99, which is responsible for lowering the oxygen affinity of the Phasianus HbD. A hydrogen bond between Thr αD34 and Pro β124, which stabilizes the de-oxy state of the hemoglobin, was observed in Phasianus colchicus. Hence it is predicted that the HbD component of Phasianus colchicus has lower oxygen affinity. All Galliformes species sequenced so far and representative species from nine different avian orders whose HbD was known were compared in this study. By analyzing the multiple sequence alignment and the Neighbor Joining Tree of αD and β chains it was revealed that all Galliformes species have closer evolutionary relationship. Among Galliformes, Phasianus colchicus has closer relation to Meleagris gallopavo (turkey) than to Gallus gallus (chicken).
