Physicochemical properties of Planorbis corneus erythrocruorin.
The erythrocruorin from the snail Planorbis corneus had a sedimentation coefficient, so/20,w, of 33.5 +/- 0.31 S, and a molecular weight of 1.65 x 10(6) +/- 0.04 x 10(6) by high-speed sedimentation-equilibrium ultracentrifugation. The amino acid composition and absorption spectrum of the protein are reported. A very low number of half-cystine residues was found, corresponding to 0.4 residue per haem group. The haem content was 2.76 +/- 0.22%, corresponding to a protein molecular weight of about 22300. Under both acid and alkaline conditions partial dissociation took place to yield mixtures of products that could not be identified. A subunit corresponding to that containing one haem group was not obtained under any of the dossociating conditions tried. Electron microscopy revealed a ring-shaped molecule about 12.2 +/- 0.5 nm in diameter. The native erythrocruorin bound O2 co-operatively, the intermediate value of h in Hill plots having values between 1.7 and 3.4 depending on the conditions.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001665:Binding Sites; D002245:Carbon Dioxide; D004220:Disulfides / Q000032:analysis; D005916:Globulins / Q000032:analysis; D006418:Heme / Q000032:analysis; D006420:Hemeproteins / Q000032:analysis*; D007700:Kinetics; D008854:Microscopy, Electron; D008970:Molecular Weight; D010100:Oxygen; D011485:Protein Binding; D011487:Protein Conformation; D012908:Snails / Q000032:analysis*; D013386:Succinates; D013696:Temperature
D000596:Amino Acids; D004220:Disulfides; D005916:Globulins; D006420:Hemeproteins; D013386:Succinates; D002245:Carbon Dioxide; D006418:Heme; D010100:Oxygen