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Vergara A, Grassi M, Sica F, Pizzo E, D'Alessio G, Mazzarella L, Merlino A. A novel interdomain interface in crystallins: structural characterization of the βγ-crystallin from Geodia cydonium at 0.99 Å resolution. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2013; 69:960-7. [PMID: 23695240 DOI: 10.1107/s0907444913003569] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 02/04/2013] [Indexed: 11/10/2022]
Abstract
The βγ-crystallin superfamily includes highly diverse proteins belonging to all of the kingdoms of life. Based on structural topology, these proteins are considered to be evolutionarily related to the long-lived βγ-crystallins that constitute the vertebrate eye lens. This study reports the crystallographic structure at 0.99 Å resolution of the two-domain βγ-crystallin (geodin) from the sponge Geodia cydonium. This is the most ancient member of the βγ-crystallin superfamily in metazoans. The X-ray structure shows that the geodin domains adopt the typical βγ-crystallin fold with a paired Greek-key motif, thus confirming the hypothesis that the crystallin-type scaffold used in the evolution of bacteria and moulds was recruited very early in metazoans. As a significant new structural feature, the sponge protein possesses a unique interdomain interface made up by pairing between the second motif of the first domain and the first motif of the second domain. The atomic resolution also allowed a detailed analysis of the calcium-binding site of the protein.
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Vergara A, D’Errico G, Montesarchio D, Mangiapia G, Paduano L, Merlino A. Interaction of Anticancer Ruthenium Compounds with Proteins: High-Resolution X-ray Structures and Raman Microscopy Studies of the Adduct between Hen Egg White Lysozyme and AziRu. Inorg Chem 2013; 52:4157-9. [DOI: 10.1021/ic4004142] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Ronda L, Merlino A, Bettati S, Verde C, Balsamo A, Mazzarella L, Mozzarelli A, Vergara A. Role of tertiary structures on the Root effect in fish hemoglobins. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:1885-93. [PMID: 23376186 DOI: 10.1016/j.bbapap.2013.01.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 01/21/2013] [Accepted: 01/23/2013] [Indexed: 10/27/2022]
Abstract
Many fish hemoglobins exhibit a marked dependence of oxygen affinity and cooperativity on proton concentration, called Root effect. Both tertiary and quaternary effects have been evoked to explain the allosteric regulation brought about by protons in fish hemoglobins. However, no general rules have emerged so far. We carried out a complementary crystallographic and microspectroscopic characterization of ligand binding to crystals of deoxy-hemoglobin from the Antarctic fish Trematomus bernacchii (HbTb) at pH6.2 and pH8.4. At low pH ligation has negligible structural effects, correlating with low affinity and absence of cooperativity in oxygen binding. At high pH, ligation causes significant changes at the tertiary structural level, while preserving structural markers of the T state. These changes mainly consist in a marked displacement of the position of the switch region CD corner towards an R-like position. The functional data on T-state crystals validate the relevance of the crystallographic observations, revealing that, differently from mammalian Hbs, in HbTb a significant degree of cooperativity in oxygen binding is due to tertiary conformational changes, in the absence of the T-R quaternary transition. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins.
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Merlino A, Fuchs MR, Pica A, Balsamo A, Dworkowski FSN, Pompidor G, Mazzarella L, Vergara A. Selective X-ray-induced NO photodissociation in haemoglobin crystals: evidence from a Raman-assisted crystallographic study. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2012; 69:137-40. [DOI: 10.1107/s0907444912042229] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 10/09/2012] [Indexed: 11/10/2022]
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Alfè M, Gargiulo V, Di Capua R, Chiarella F, Rouzaud JN, Vergara A, Ciajolo A. Wet chemical method for making graphene-like films from carbon black. ACS APPLIED MATERIALS & INTERFACES 2012; 4:4491-4498. [PMID: 22891711 DOI: 10.1021/am301197q] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Reduction of strongly oxidized carbon black by hydrazine hydrate yields water-insoluble graphene-like sheets that undergo to self-assembling in thin film on surfaces after drying. The height of a drop-casted graphene-like film was determined by atomic force microscopy (AFM) to be around 20 nm, corresponding to approximately 25 graphene-like layers. The oxidized carbon black and the corresponding reduced form were carefully characterized.
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Conter M, Di Ciccio P, Zanardi E, Ghidini S, Borracci G, Vergara A, Ianieri A. METHICILLIN - RESISTANT STAPHYLOCOCCUS AUREUS IN PIG PRODUCTION CHAIN. Ital J Food Saf 2012. [DOI: 10.4081/ijfs.2012.3.25] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Balsamo A, Sannino F, Merlino A, Parrilli E, Tutino ML, Mazzarella L, Vergara A. Role of the tertiary and quaternary structure in the formation of bis-histidyl adducts in cold-adapted hemoglobins. Biochimie 2012; 94:953-60. [DOI: 10.1016/j.biochi.2011.12.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 12/14/2011] [Indexed: 10/14/2022]
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58
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Merlino A, Russo Krauss I, Rossi B, Vergara A, De Vendittis A, Marco S, De Vendittis E, Sica F. Identification of an active dimeric intermediate populated during the unfolding process of the cambialistic superoxide dismutase from Streptococcus mutans. Biochimie 2012; 94:768-75. [DOI: 10.1016/j.biochi.2011.11.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Accepted: 11/18/2011] [Indexed: 10/15/2022]
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Paludi D, Vergara A, Festino AR, Di Ciccio P, Costanzo C, Conter M, Zanardi E, Ghidini S, Ianieri A. Antimicrobial resistance pattern of methicillin-resistant Staphylococcus aureus in the food industry. J BIOL REG HOMEOS AG 2011; 25:671-677. [PMID: 22218000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
There is increasing concern about the impact on public health of methicillin-resistant Staphylococcus aureus (MRSA) associated with animal food products. MRSA remains a serious problem because of the high incidence and multidrug resistance of the strains, even for strains isolated from foods, food environments and food handlers. The objectives of this study are: (i) to evaluate the susceptibility of S. aureus strains isolated from food, food handlers and food-processing environments to 14 antibiotics currently used in veterinary and human therapy; (ii) to assess the presence of the mecA gene. A total of 1007 samples were collected from food, food handlers, and environments and were analyzed for the presence of S. aureus. S. aureus was present in 165 of the 1007 samples. A total of 157 isolates were methicillin-susceptible S. aureus (MSSA) and 8 isolates were MRSA. In particular, out of 8 MRSA strains detected, 4 strains harboured the mecA gene. All MRSA strains were resistant to at least one of the tested antibiotics and 6 strains demonstrated multi-resistance. Considering the high level of resistances in S. aureus and the isolation of MRSA strains, the surveillance of antimicrobial resistance and the spreading of this pathogen is of crucial importance in the food production chain. These data are useful in improving background data on antimicrobial resistance of S. aureus isolated from food, processing environments and food handlers, supporting the prudent use of antibiotics and the development of international control programs.
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Pica A, Merlino A, Balsamo A, Mazzarella L, Vergara A. Raman assisted X-ray crystallographic study of nitric oxide binding to deoxygenated hemoglobins. Acta Crystallogr A 2011. [DOI: 10.1107/s0108767311086016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Pennisi L, Sili F, Costanzo C, Vergara A. SURVEY ON SOLIDARITY GROUPS OF BUYERS: CRITICAL ISSUES. Ital J Food Saf 2011. [DOI: 10.4081/ijfs.2011.2.49] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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62
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Merlino A, Howes BD, Prisco GD, Verde C, Smulevich G, Mazzarella L, Vergara A. Occurrence and formation of endogenous histidine hexa-coordination in cold-adapted hemoglobins. IUBMB Life 2011; 63:295-303. [PMID: 21491555 DOI: 10.1002/iub.446] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Accepted: 02/11/2011] [Indexed: 11/06/2022]
Abstract
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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Riccio A, Mangiapia G, Giordano D, Flagiello A, Tedesco R, Bruno S, Vergara A, Mazzarella L, di Prisco G, Pucci P, Paduano L, Verde C. Polymerization of hemoglobins in Arctic fish: Lycodes reticulatus and Gadus morhua. IUBMB Life 2011; 63:346-54. [DOI: 10.1002/iub.450] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Accepted: 02/16/2011] [Indexed: 12/29/2022]
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Boechi L, Martì MA, Vergara A, Sica F, Mazzarella L, Estrin DA, Merlino A. Protonation of histidine 55 affects the oxygen access to heme in the alpha chain of the hemoglobin from the Antarctic fish Trematomus bernacchii. IUBMB Life 2011; 63:175-82. [DOI: 10.1002/iub.436] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Belmar P, de Eusebio E, Sánchez C, Vergara A, Martín A, Juanes A, Jiménez E, Diez E, Pastor MA, Olivares M. [Paramedian forehead flap for the reconstruction of extensive nasal defects]. ACTAS DERMO-SIFILIOGRAFICAS 2011; 102:187-92. [PMID: 21377637 DOI: 10.1016/j.ad.2010.10.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 09/19/2010] [Accepted: 10/01/2010] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND The Department of Dermatology at Hospital Universitario de Guadalajara in Spain is a referral center for Mohs micrographic surgery. Consequently, we are regularly faced with the problem of repairing large surgical defects on the nose. The paramedian forehead flap is currently one of the techniques of choice for the repair of such defects. MATERIALS AND METHODS We review our experience in the repair of nasal defects using the paramedian forehead flap over the period from 2004 to 2008. We describe the surgical technique, complications, and final results. RESULTS Ten patients (mean age, 75.1 years) were treated using this flap. Two patients also required cartilage grafts and reconstruction of the internal nasal lining. The most common complications were bleeding (60%) and partial necrosis (10%). The final cosmetic and functional results were considered good or excellent in 90% of cases. CONCLUSIONS The forehead flap continues to be one of the best options for the closure of surgical defects of the nasal pyramid larger than 2 cm. Adequate knowledge and careful application of the technique allows excellent results to be obtained with few complications.
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Belmar P, de Eusebio E, Sánchez C, Vergara A, Martín A, Juanes A, Jiménez E, Diez E, Pastor M, Olivares M. Paramedian Forehead Flap for the Reconstruction of Extensive Nasal Defects. ACTAS DERMO-SIFILIOGRAFICAS 2011. [DOI: 10.1016/s1578-2190(11)70783-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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67
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Merlino A, Vitagliano L, Balsamo A, Nicoletti FP, Howes BD, Giordano D, Coppola D, di Prisco G, Verde C, Smulevich G, Mazzarella L, Vergara A. Crystallization, preliminary X-ray diffraction studies and Raman microscopy of the major haemoglobin from the sub-Antarctic fish Eleginops maclovinus in the carbomonoxy form. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:1536-40. [PMID: 21045316 DOI: 10.1107/s1744309110038698] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Accepted: 09/27/2010] [Indexed: 11/10/2022]
Abstract
The blood of the sub-Antarctic fish Eleginops maclovinus (Em) contains three haemoglobins. The major haemoglobin (Hb1Em) displays the Root effect, a drastic decrease in the oxygen affinity and a loss of cooperativity at acidic pH. The carbomonoxy form of HbEm1 has been crystallized in two different crystal forms, orthorhombic (Ortho) and hexagonal (Hexa), and high-resolution diffraction data have been collected for both forms (1.45 and 1.49 Å resolution, respectively). The high-frequency resonance Raman spectra collected from the two crystal forms using excitation at 514 nm were almost indistinguishable. Hb1Em is the first sub-Antarctic fish Hb to be crystallized and its structural characterization will shed light on the molecular mechanisms of cold adaptation and the role of the Root effect in fish haemoglobins.
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Vergara A, Vitagliano L, Merlino A, Sica F, Marino K, Verde C, di Prisco G, Mazzarella L. An order-disorder transition plays a role in switching off the root effect in fish hemoglobins. J Biol Chem 2010; 285:32568-75. [PMID: 20610398 PMCID: PMC2952259 DOI: 10.1074/jbc.m110.143537] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 06/17/2010] [Indexed: 11/06/2022] Open
Abstract
The Root effect is a widespread property among fish hemoglobins whose structural basis remains largely obscure. Here we report a crystallographic and spectroscopic characterization of the non-Root-effect hemoglobin isolated from the Antarctic fish Trematomus newnesi in the deoxygenated form. The crystal structure unveils that the T state of this hemoglobin is stabilized by a strong H-bond between the side chains of Asp95α and Asp101β at the α(1)β(2) and α(2)β(1) interfaces. This unexpected finding undermines the accepted paradigm that correlates the presence of this unusual H-bond with the occurrence of the Root effect. Surprisingly, the T state is characterized by an atypical flexibility of two α chains within the tetramer. Indeed, regions such as the CDα corner and the EFα pocket, which are normally well ordered in the T state of tetrameric hemoglobins, display high B-factors and non-continuous electron densities. This flexibility also leads to unusual distances between the heme iron and the proximal and distal His residues. These observations are in line with Raman micro-spectroscopy studies carried out both in solution and in the crystal state. The findings here presented suggest that in fish hemoglobins the Root effect may be switched off through a significant destabilization of the T state regardless of the presence of the inter-aspartic H-bond. Similar mechanisms may also operate for other non-Root effect hemoglobins. The implications of the flexibility of the CDα corner for the mechanism of the T-R transition in tetrameric hemoglobins are also discussed.
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Vergara A. Monitoring the preparation of protein derivative crystals viaRaman microscopy. Acta Crystallogr A 2010. [DOI: 10.1107/s0108767310097965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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70
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Merlino A, Russo Krauss I, Castellano I, De Vendittis E, Rossi B, Conte M, Vergara A, Sica F. Structure and flexibility in cold-adapted iron superoxide dismutases: the case of the enzyme isolated from Pseudoalteromonas haloplanktis. J Struct Biol 2010; 172:343-52. [PMID: 20732427 DOI: 10.1016/j.jsb.2010.08.008] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 07/29/2010] [Accepted: 08/18/2010] [Indexed: 10/19/2022]
Abstract
Superoxide dismutases (SODs) are metalloenzymes catalysing the dismutation of superoxide anion radicals into molecular oxygen and hydrogen peroxide. Here, we present the crystal structure of a cold-adapted Fe-SOD from the Antarctic eubacterium Pseudoalteromonas haloplanktis (PhSOD), and that of its complex with sodium azide. The structures were compared with those of the corresponding homologues having a high sequence identity with PhSOD, such as the mesophilic SOD from Escherichia coli (EcSOD) or Pseudomonas ovalis, and the psychrophilic SOD from Aliivibrio salmonicida (AsSOD). These enzymes shared a large structural similarity, such as a conserved tertiary structure and arrangement of the two monomers, an almost identical total number of inter- and intramolecular hydrogen bonds and salt bridges. However, the two cold-adapted SODs showed an increased flexibility of the active site residues with respect to their mesophilic homologues. Structural information was combined with a characterisation of the chemical and thermal stability performed by CD and fluorescence measurements. Despite of its psychrophilic origin, the denaturation temperature of PhSOD was comparable with that of the mesophilic EcSOD, whereas AsSOD showed a lower denaturation temperature. On the contrary, the values of the denaturant concentration at the transition midpoint were in line with the psychrophilic/mesophilic origin of the proteins. These data provide additional support to the hypothesis that cold-adapted enzymes achieve efficient catalysis at low temperature, by increasing the flexibility of their active site; moreover, our results underline how fine structural modifications can alter enzyme flexibility and/or stability without compromising the overall structure of typical rigid enzymes, such as SODs.
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Vergara A, Festino A, Di Ciccio P, Pennisi L, Conter M, Costanzo C, Ianieri A. THE MANAGEMENT OF THE DOMESTIC REFRIGERATION: HYGIENIC AND SANITARY CHARACTERISTICS OF REFRIGERATORS FROM NORTHEN AND CENTRAL ITALY. Ital J Food Saf 2010. [DOI: 10.4081/ijfs.2010.8.13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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72
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Merlino A, Vergara A, Sica F, Aschi M, Amadei A, Di Nola A, Mazzarella L. Free-Energy Profile for CO Binding to Separated Chains of Human and Trematomus newnesi Hemoglobin: Insights from Molecular Dynamics Simulations and Perturbed Matrix Method. J Phys Chem B 2010; 114:7002-8. [DOI: 10.1021/jp908525s] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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73
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Merlino A, Russo Krauss I, Perillo M, Mattia CA, Ercole C, Picone D, Vergara A, Sica F. Toward an antitumor form of bovine pancreatic ribonuclease: the crystal structure of three noncovalent dimeric mutants. Biopolymers 2010; 91:1029-37. [PMID: 19280639 DOI: 10.1002/bip.21183] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The cytotoxic action of bovine seminal ribonuclease (BS-RNase) depends on its noncovalent swapped dimeric form (NCD-BS), which presents a compact structure that allows the molecule to escape ribonuclease inhibitor (RI). A key role in the acquisition of this structure has been attributed to the concomitant presence of a proline in position 19 and a leucine in position 28. The introduction of Leu28, Cys31, and Cys32 and, in addition, of Pro19 in the sequence of bovine pancreatic ribonuclease (RNase A) has produced two dimeric variants LCC and PLCC, which do exhibit a cytotoxic activity, though at a much lower level than BS-RNase. The crystal structure analysis of the noncovalent swapped form (NCD) of LCC and PLCC, complexed with the substrate analogue 2 '-deoxycytidylyl(3 ',5 ')-2 '-deoxyguanosine, has revealed that, differently from NCD-BS, the dimers adopt an opened quaternary structure, with the two Leu residues fully exposed to the solvent, that does not hinder the binding of RI. Similar results have been obtained for a third mutant of the pancreatic enzyme, engineered with the hinge peptide sequence of the seminal enzyme (residues 16-22) and the two cysteines in position 31 and 32, but lacking the hydrophobic Leu residue in position 28. The comparison of these three structures with those previously reported for other ribonuclease swapped dimers strongly suggests that, in addition to Pro19 and Leu28, the presence of a glycine at the N-terminal end of the hinge peptide is also important to push the swapped form of RNase A dimer into the compact quaternary organization observed for NCD-BS.
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Vergara A, Franzese M, Merlino A, Bonomi G, Verde C, Giordano D, di Prisco G, Lee HC, Peisach J, Mazzarella L. Correlation between hemichrome stability and the root effect in tetrameric hemoglobins. Biophys J 2009; 97:866-74. [PMID: 19651045 DOI: 10.1016/j.bpj.2009.04.056] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Revised: 04/23/2009] [Accepted: 04/28/2009] [Indexed: 10/20/2022] Open
Abstract
Oxidation of Hbs leads to the formation of different forms of Fe(III) that are relevant to a range of biochemical and physiological functions. Here we report a combined EPR/x-ray crystallography study performed at acidic pH on six ferric tetrameric Hbs. Five of the Hbs were isolated from the high-Antarctic notothenioid fishes Trematomus bernacchii, Trematomus newnesi, and Gymnodraco acuticeps, and one was isolated from the sub-Antarctic notothenioid Cottoperca gobio. Our EPR analysis reveals that 1), in all of these Hbs, at acidic pH the aquomet form and two hemichromes coexist; and 2), only in the three Hbs that exhibit the Root effect is a significant amount of the pentacoordinate (5C) high-spin Fe(III) form found. The crystal structure at acidic pH of the ferric form of the Root-effect Hb from T. bernacchii is also reported at 1.7 A resolution. This structure reveals a 5C state of the heme iron for both the alpha- and beta-chains within a T quaternary structure. Altogether, the spectroscopic and crystallographic results indicate that the Root effect and hemichrome stability at acidic pH are correlated in tetrameric Hbs. Furthermore, Antarctic fish Hbs exhibit higher peroxidase activity than mammalian and temperate fish Hbs, suggesting that a partial hemichrome state in tetrameric Hbs, unlike in monomeric Hbs, does not remove the need for protection from peroxide attack, in contrast to previous results from monomeric Hbs.
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Suarez-Lozano I, Viciana P, Lacalle JR, Teira R, Lozano F, Lopez-Aldeguer J, Pedrol E, Domingo P, Cosin J, Roca B, Geijo P, Fuente B, Vergara A, Ribera E, Galindo MJ, Zapata A, Sanchez T, Vidal F, Munoz-Sanz A, Munoz-Sanchez J, Garrido M. The relationship between antiretroviral prescription patterns and treatment guidelines in treatment-naïve HIV-1-infected patients. HIV Med 2009; 10:573-9. [DOI: 10.1111/j.1468-1293.2009.00731.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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