A re-evaluation of the molecular mass of earthworm extracellular hemoglobin from meniscus depletion sedimentation equilibrium. Nature of the 10 S dissociation species.
Previous calculations from meniscus depletion sedimentation equilibrium earthworm hemoglobin from Lumbricus terrestris (E.J. Wood et al., Biochem. J. 153 (1976) 589-96) and from the related species Lumbricus sp. (L. sp.) (M.M. David and E. D Mol. Biol. 87 (1974) 89--101) were made on the assumption that the solutions behaved ideally. Re-examination of their results reveals, however, a dependence of the apparent molecular mass on concentration. Taking this effect into consideration, we have nowrecalculated from their data molecular masses of 4.4--4.5 MDa for the hemoglobin of both L. terrestris and L. sp. On the basis of the new determinations, we propose for the polypeptide chain composition of L. terrestris hemoglobin a model [(abcd )4L1L2L3]12 where a,b,c,d are the four globin and L1,L2,L3 are the three major linker chain constituents of the protein. The model is consistent with the D6 symmetry of the molecule. A 10 S intermediate product in the alkaline dissociation Lumbricus hemoglobin is viewed as a binary mixture of products resulting from a disproportionation reaction involving the structural unit. The present interpretation is shown to be consistent with observed relations between molecular masses and SDS gel electrophoretic band patterns of 10 S species and intact hemoglobin.
Tsfadia
Y
Y
Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
Daniel
E
E
D000818:Animals; D006454:Hemoglobins / Q000737:chemistry*; D016014:Linear Models; D008722:Methods; D015394:Molecular Structure; D008970:Molecular Weight; D009835:Oligochaeta / Q000737:chemistry* / Q000235:genetics
D006454:Hemoglobins