Bothrops alternatus hemoglobin components. Oxygen binding properties and globin chain hydrophobic analysis

Abstract

1. 1. Bothrops alternatus oxyhemolysate showed two components by DE-52 cellulose ion-exchange chromatography and polyacrylamide gel electrophoresis: Hb I representing 70% of the hemolysate and Hb II (30%); both are dimeric in the stripped from (mol.wt 32,500 Da) and tetrameric in the presence of IHP (64,000 Da). 2. 2. Hb I, Hb II and whole hemolysate showed functionally similar properties to those of Liophis miliaris, i.e. for the stripped form over the pH interval 7.2–8.9; log P 50 values decreasing from ±0.1 to ± −0.15 (thereby an alkaline Bohr effect); ΔH + = −0.38 and Hill coefficient values decreasing from n H = 1.5 to 1.0. In the presence of ATP, an abrupt decrease in O 2 affinity occurs and the log P 50 values change from 1.0 to 0.5; the Bohr effect increases to ΔH + = −0.7 whereas the n H values decrease from ⩾2 to values close to unity. 3. 3. For B. alternatus, at a physiological pH range (7.8–9.0) the hemoglobin Bohr effect becomes apparent only in the presence of ATP and this seems to be fundamental for the O 2 uptake of the snake. 4. 4. HPLC analysis of the globins shows eight different chains instead of four, as found in L. miliaris hemoglobin, which corroborates the presence of Hb I and Hb II components in B. alternatus, and also shows that the unique tetramer formed from different α and β chains is also consistent in this snake.