title: The cooperativity of human fetal and adult hemoglobins is optimized: a consideration based on the effectiveness of the Bohr shift.
abstract: The physiological significance of the cooperativity of human hemoglobin (Hb) is considered from the viewpoint of the effectiveness of the Bohr shift at the sites of O(2) release and uptake across the placental membrane. The effects of the Bohr shift was examined by changing the O(2) saturation of Hb (S(pO2)) per unit change in P(50), -dS(PO2)/d P(50), where P(50) is partial pressure of O(2) at half saturation. The Bohr shift at the sites of O(2) uptake and release was found to be highly effective in both fetal and maternal bloods at physiological degree of cooperativity (Hill's coefficient, n=2.65). From the results obtained in this paper, it is concluded that the positions of OECs of fetal and maternal Hbs are regulated to receive a maximal benefit from the Bohr shift, and that a relatively low n value of human tetrameric Hb is adequate for the O(2) and CO(2) exchange across the placental membrane.
authors.affiliation: Graduate school of Science and Technology, Niigata University, Japan.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Makoto
authors.initials: M
authors.lastname: Miki
authors.forename: Keisuke
authors.initials: K
authors.lastname: Sasagawa
authors.forename: Michisuke
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Kiyohiro
authors.initials: K
authors.lastname: Imai
authors.forename: Michiyori
authors.initials: M
authors.lastname: Kobayashi
mesh_terms: D000494:Allosteric Regulation; D005260:Female; D005319:Fetal Hemoglobin / Q000737:chemistry* / Q000378:metabolism*; D006454:Hemoglobins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008431:Maternal-Fetal Exchange; D008954:Models, Biological; D010100:Oxygen / Q000097:blood* / Q000378:metabolism*; D010313:Partial Pressure; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy
chemical_list: D006454:Hemoglobins; D005319:Fetal Hemoglobin; D010100:Oxygen