HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zhu, H. Articles by Riggs, A. F. Search for Related Content PubMed PubMed Citation Articles by Zhu, H. Articles by Riggs, A. F. Social Bookmarking                      What's this?

Volume 271, Number 47, Issue of November 22, 1996 pp. 30007-30021
©1996 by The American Society for Biochemistry and Molecular Biology, Inc.

---

Assembly of the Gigantic Hemoglobin of the Earthworm Lumbricus terrestris
ROLES OF SUBUNIT EQUILIBRIA, NON-GLOBIN LINKER CHAINS, AND VALENCE OF THE HEME IRON

(Received for publication, June 28, 1996, and in revised form, September 5, 1996)

Hao Zhu , David W. Ownby , Claire K. Riggs , Norman J. Nolasco , James K. Stoops and Austen F. Riggs

From the  Department of Zoology, University of Texas, Austin, Texas 78712-1064 and  Department of Pathology and Laboratory Medicine, University of Texas Health Science Center, Houston, Texas 77030

The extracellular hemoglobin of the earthworm Lumbricus terrestris has four major kinds of O₂-binding chains: a, b, and c (forming a disulfide-linked trimer), and chain d. Non-heme, non-globin structural chains, "linkers," are also present. Light-scattering techniques have been used to show that the ferrous CO-saturated abc trimer and chain d form an (abcd)₄ complex of 285 kDa at neutral pH. Formation of the full-sized 4-MDa molecule requires the addition of linker chains in the proportion of two linkers per (abcd)₄ and occurs much more rapidly in the presence of 10 mM calcium. This stoichiometry is supported not only by direct quantitative analysis of the intact hemoglobin but also by the fact that the addition of 50% of the proposed stoichiometric quantity of linkers results in the conversion of 50% of the (abcd)₄ to full-sized molecules. Isolated CO-saturated abc trimers self-associate to (abc)₂ and higher aggregates up to an apparent limit of (abc)₁₀ ~550 kDa. The CO-saturated chain d forms dimers, (d)₂, and tetramers, (d)₄. Oxidation of the (abcd)₄ complex with ferricyanide causes complete dissociation of chain d from the abc trimer, but addition of CN maintains the (abcd)₄ complex. Valence hybrids have also been studied. The ferrous CO-saturated abc trimer and met (ferric) chain d also associate to form (abcd)₄, but the met abc trimer and ferrous CO-saturated chain d do not. Oxidation of the abc trimer and chain d to the ferric form causes the formation of a characteristic hemichrome spectrum with a maximum at 565 nm and a shoulder near 530 nm. These results show that interactions between the abc trimer and chain d are strongly dependent on the ligand and valence state of the heme iron. Light-scattering measurements reveal that oxidation of the intact Hb produces a significant drop in molecular mass from 4.1 to 3.6 MDa. Inclusion of CN prevents this drop. These experiments indicate that oxidation causes the Hb to shed subunits. The observations provide an explanation for the wide variations in the molecular mass of L. terrestris Hb that have been observed previously.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				P. S. Santiago, F. Moura, L. M. Moreira, M. M. Domingues, N. C. Santos, and M. Tabak Dynamic Light Scattering and Optical Absorption Spectroscopy Study of pH and Temperature Stabilities of the Extracellular Hemoglobin of Glossoscolex paulistus Biophys. J., March 15, 2008; 94(6): 2228 - 2240. [Abstract] [Full Text] [PDF]

				W. E. Royer Jr., H. Zhu, T. A. Gorr, J. F. Flores, and J. E. Knapp Allosteric Hemoglobin Assembly: Diversity and Similarity J. Biol. Chem., July 29, 2005; 280(30): 27477 - 27480. [Full Text] [PDF]

				R. Diaz-Avalos, C.-Y. King, J. Wall, M. Simon, and D. L. D. Caspar Strain-specific morphologies of yeast prion amyloid fibrils PNAS, July 19, 2005; 102(29): 10165 - 10170. [Abstract] [Full Text] [PDF]

				A. Krebs, H. Durchschlag, and P. Zipper Small Angle X-Ray Scattering Studies and Modeling of Eudistylia vancouverii Chlorocruorin and Macrobdella decora Hemoglobin Biophys. J., August 1, 2004; 87(2): 1173 - 1185. [Abstract] [Full Text] [PDF]

				R. E. Weber and S. N. Vinogradov Nonvertebrate Hemoglobins: Functions and Molecular Adaptations Physiol Rev, April 1, 2001; 81(2): 569 - 628. [Abstract] [Full Text] [PDF]

				W. E. Royer Jr., K. Strand, M. van Heel, and W. A. Hendrickson Structural hierarchy in erythrocruorin, the giant respiratory assemblage of annelids PNAS, June 20, 2000; 97(13): 7107 - 7111. [Abstract] [Full Text] [PDF]

				B. N. Green, R. S. Bordoli, L. G. Hanin, F. H. Lallier, A. Toulmond, and S. N. Vinogradov Electrospray Ionization Mass Spectrometric Determination of the Molecular Mass of the ~200-kDa Globin Dodecamer Subassemblies in Hexagonal Bilayer Hemoglobins J. Biol. Chem., October 1, 1999; 274(40): 28206 - 28212. [Abstract] [Full Text] [PDF]

				Y. Qiu, L. Sutton, and A. F. Riggs Identification of Myoglobin in Human Smooth Muscle J. Biol. Chem., September 4, 1998; 273(36): 23426 - 23432. [Abstract] [Full Text] [PDF]

				H. Zhu, M. Hargrove, Q. Xie, Y. Nozaki, K. Linse, S. S. Smith, J. S. Olson, and A. F. Riggs Stoichiometry of Subunits and Heme Content of Hemoglobin from the Earthworm Lumbricus terrestris J. Biol. Chem., November 22, 1996; 271(47): 29999 - 30006. [Abstract] [Full Text] [PDF]