Structural Analysis of Monomeric Hemichrome and Dimeric Cyanomet Hemoglobins fromCaudina arenicola

Mitchell, David; Kitto, G. Barrie; Hackert, Marvin L.

doi:10.1006/jmbi.1995.0445

Cited by 60 publications

(49 citation statements)

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“…4A) is smaller than that of the NMR structure (Fig. 4B), which is more extensive and reaches into the heme pocket to surround the distal His 46 . block the heme from solvent accessibility at the CHD methinic bridge (13).…”

Section: Resultsmentioning

confidence: 77%

“…The H helix is closer to the heme in the crystal structure, which brings His 117 into position to form a covalent bond to the heme 2-vinyl group. Additional high resolution structural differences include the position of the side chains of the proximal and distal histidines, His 70 and His 46 , respectively (Table II), which have different orientations with respect to the heme porphyrins in the two structures. The proximal histidine in the crystal structure is tilted toward the propionates with an acute angle of 79°between the least squares planes of the heme porphyrin and the histidine imid- azole ring, whereas in the NMR structure the proximal histidine is tilted away from the propionates with an acute angle of 77°.…”

Section: Resultsmentioning

confidence: 99%

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The Crystal Structure of Synechocystis Hemoglobin with a Covalent Heme Linkage

Hoy

Kundu

Trent

et al. 2004

Journal of Biological Chemistry

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The x-ray crystal structure of Synechocystis hemoglobin has been solved to a resolution of 1.8 Å. The conformation of this structure is surprisingly different from that of the previously reported solution structure, probably due in part to a covalent linkage between the heme 2-vinyl and His 117 that is present in the crystal structure but not in the structure solved by NMR. Synechocystis hemoglobin is a hexacoordinate hemoglobin in which the heme iron is coordinated by both the proximal and distal histidines. It is also a member of the "truncated hemoglobin" family that is much shorter in primary structure than vertebrate and plant hemoglobins. In contrast to other truncated hemoglobins, the crystal structure of Synechocystis hemoglobin displays no "ligand tunnel" and shows that several important amino acid side chains extrude into the solvent instead of residing inside the heme pocket. The stereochemistry of hexacoordination is compared with other hexacoordinate hemoglobins and cytochromes in an effort to illuminate factors contributing to ligand affinity in hexacoordinate hemoglobins.

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Section: Resultsmentioning

confidence: 77%

Section: Resultsmentioning

confidence: 99%

The Crystal Structure of Synechocystis Hemoglobin with a Covalent Heme Linkage

Hoy

Kundu

Trent

et al. 2004

Journal of Biological Chemistry

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“…In both Hbs, careful inspection of the RR spectra reveals the immediate appearance of an aquo hexacoordinate high-spin ferric form. The spectra after 3 h show a band assigned to the m 3 6cHS mode, that appears as a shoulder of the deoxy band at m 3 1470 cm 21 , due to laser-induced photolysis of the CO ligand. The frequency shifts of the m 3 and m 2 bands upon autoxidation to 1505 and 1579 cm -1 (1578 cm -1 for Hb1Tn) are consistent with the formation of a hexa-coordinate bis-His (hemichrome) form.…”

Section: Mechanism Of Hemichrome Formation In Tetrameric Hbs Of Antarmentioning

confidence: 99%

“…To date, only a few Hb structures with bis-histidyl endogenous coordination have been deposited in the PDB (10,(21)(22)(23)(24)(25)(26)(27)(28)(29).…”

Section: Occurrence Of Bis-histidyl Adductsmentioning

confidence: 99%

Occurrence and formation of endogenous histidine hexa‐coordination in cold‐adapted hemoglobins

et al. 2011

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Spectroscopic and crystallographic evidence of endogenous (His) ligation at the sixth coordination site of the heme iron has been reported for monomeric, dimeric, and tetrameric hemoglobins (Hbs) in both ferrous (hemochrome) and ferric (hemichrome) oxidation states. In particular, the ferric bis- histidyl adduct represents a common accessible ordered state for the β chains of all tetrameric Hbs isolated from Antarctic and sub-Antarctic fish. Indeed, the crystal structures of known tetrameric Hbs in the bis-His state are characterized by a different binding state of the α and β chains. An overall analysis of the bis-histidyl adduct of globin structures deposited in the Protein Data Bank reveals a marked difference between hemichromes in tetrameric Hbs compared to monomeric/dimeric Hbs. Herein, we review the structural, spectroscopic and stability features of hemichromes in tetrameric Antarctic fish Hbs. The role of bis-histidyl adducts is also addressed in a more evolutionary context alongside the concept of its potential physiological role

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“…Animal Hbs can be grouped into three separate clades in a manner that is consistent with the nature of the circulatory system of the corresponding organism and with how the oxygen transport Hbs are packaged within the circulatory system. In the phylogeny shown in Figure 3, The animal hxHbs that are most closely related to the cellbound Hbs in closed circulatory systems are the "cytoglobins" (Cgb) found in vertebrates and "Hb Chain C" from the sea cucumber Caudina arenicola [2,40,45]. The two other vertebrate hxHbs, "neuroglobins" (Ngb) and "globin X" (GlbX), are more closely related to extracellular oxygen transport Hbs present in animals with closed circulatory systems [19,43,44].…”

Section: Animal Hemoglobinsmentioning

confidence: 99%

Structure and Reactivity of Hexacoordinate Hemoglobins

Hargrove

Sturms

2013

Free Radical Biology and Medicine

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The term "hemoglobin" has spent decades at the forefront of biochemical research, including the eras of "grind-and-find", protein structure determination, and the relationship between protein structure and function. It has also served as a familiar target in genomic annotation, and as a guidepost to study the evolution of primary structure and protein function. We have learned over the past fifteen years that most organisms contain genes with homology to globins, and that not all glo- AbstractThe heme prosthetic group in hemoglobins is most often attached to the globin through coordination of either one or two histidine side chains. Those proteins with one histidine coordinating the heme iron are called "pentacoordinate" hemoglobins, a group represented by red blood cell hemoglobin and most other oxygen transporters. Those with two histidines are called "hexacoordinate hemoglobins", which have broad representation among eukaryotes. Coordination of the second histidine in hexacoordinate Hbs is reversible, allowing for binding of exogenous ligands like oxygen, carbon monoxide, and nitric oxide. Research over the past several years has produced a fairly detailed picture of the structure and biochemistry of hexacoordinate hemoglobins from several species including neuroglobin and cytoglobin in animals, and the nonsymbiotic hemoglobins in plants. However, a clear understanding of the physiological functions of these proteins remains an elusive goal.

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Structural Analysis of Monomeric Hemichrome and Dimeric Cyanomet Hemoglobins fromCaudina arenicola

Cited by 60 publications

References 0 publications

The Crystal Structure of Synechocystis Hemoglobin with a Covalent Heme Linkage

The Crystal Structure of Synechocystis Hemoglobin with a Covalent Heme Linkage

Occurrence and formation of endogenous histidine hexa‐coordination in cold‐adapted hemoglobins

Structure and Reactivity of Hexacoordinate Hemoglobins

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