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Primary structure of hemoglobin from cobra Naja naja naja
1H.E.J. Research Institute of Chemistry, University of Karachi, Pakistan.
Insights
This study details the primary structure of Naja naja naja hemoglobin, revealing significant variations from human and other reptile hemoglobins. These findings offer insights into land snake hemoglobin evolution and function.
Area of Science:
- Biochemistry
- Molecular Biology
- Evolutionary Biology
Background:
- Hemoglobin structure and function are crucial for oxygen transport.
- Limited data exists on land snake hemoglobin primary structure.
- Previous studies focused on sea snake hemoglobins.
Purpose of the Study:
- To determine the primary amino acid sequence of Naja naja naja hemoglobin.
- To compare land snake hemoglobin with human and other reptile hemoglobins.
- To investigate evolutionary variations in hemoglobin structure.
Main Methods:
- Polypeptide chain separation using ion exchange chromatography.
- Amino acid sequencing via automatic Edman degradation.
- Analysis of native chains and tryptic/hydrolytic peptides.
Main Results:
- The primary structure of one alpha and one beta chain of Naja naja naja hemoglobin was elucidated.
- Significant amino acid variations were observed compared to human and other reptile hemoglobins.
- Exchanges affect subunit contacts and heme binding sites.
Conclusions:
- This is the first report on the hemoglobin primary structure of a land snake.
- The findings highlight substantial evolutionary divergence within reptile hemoglobins.
- Structural variations may impact oxygen-binding properties and physiological adaptations.
Abstract:
Cobra snake Naja naja naja hemoglobin shows four bands on Triton electrophoresis. We present the primary structure of one alpha and one beta chain. The separation of polypeptide chains was achieved by ion exchange chromatography on carboxymethyl cellulose column. The amino acid sequence was established by automatic Edman degradation of the native chains and tryptic and hydrolytic peptides in a gas-phase sequencer. The structural data are compared with those of human and other reptile hemoglobins and reveal not only large variations from human but within reptiles. The amino acid exchanges involve several subunit contacts and heme binding sites. This is the first study on the hemoglobin of a land snake. There are only two amino acid sequences of sea snake hemoglobin (Microcephalophis gracilis gracilis and Liophis miliaris) reported in the literature.