Complexometric determination of iron in heme proteins with 4-(2-pyridylazo)resorcinol

Stoichiometry of Subunits and Heme Content of Hemoglobin from the Earthworm Lumbricus terrestris

“…The higher apparent precision of the phenanthroline measurements led to the conclusion (3) that it was also more accurate. 8 However, human Hb was also analyzed with 1,10-phenanthroline at the same time as the L. terrestris experiments were performed (33). The iron content of human Hb was given as 0.311 Ϯ 0.0013% (ϭ3.43% heme), but this is about 10% lower than the value expected on the basis of the known sequences: 3.83%.…”

Giant Hexagonal Bilayer Hemoglobins

“…The average ESI-MS mass of the four globin chains of Lumbricus Hb is 17.8 × 10 3 , corresponding to an iron content of 0.31 wt %, which should be compared to the experimentally determined values for the Hb, 0.221−0.230 wt %: ,, it is clear that globin chains account for only 70−74% of the total Hb mass. The ESI-MS results 22 also show that chain a and linker L1 have glycan side chains, providing a calculated carbohydrate content of 2.1% (on the basis of 36 chain a and 12 L1 ) in good agreement with the earlier value (section II.B).…”

“…This cornucopia of detailed mass information has allowed the verification of the known globin and linker sequences and has allowed us to propose suitable models of the quaternary structures with much greater confidence than heretofore possible. 22,24,[36][37][38] The average ESI-MS mass of the four globin chains of Lumbricus Hb is 17.8 × 10 3 , corresponding to an iron content of 0.31 wt %, 22 which should be compared to the experimentally determined values for the Hb, 0.221-0.230 wt %: 41,43,61 it is clear that globin chains account for only 70-74% of the total Hb mass. The ESI-MS results 22 also show that chain a and linker L1 have glycan side chains, providing a calculated carbohydrate content of 2.1% (on the basis of 36 chain a and 12 L1) in good agreement with the earlier value (section II.B).…”

Fate of blood meal iron in mosquitoes

“…In Kogan's meal, the γ-globulins were thought to initiate the hormonal responses necessary for normal egg development, hemoglobin was used as a visual marker of feeding and albumin as a concentrated source of protein to achieve egg yields equivalent to those from blood-fed controls (Kogan, 1990). Heme is 3.43% of the mass of hemoglobin; the remainder is globin (Vinogradov et al, 1982). In order to compensate for the removal of globin, we added an equivalent amount of protein as albumin and γ-globulin based on the mass ratio of both components in the original Kogan's meal (20:3).…”