Hb Mobile [α2β2 73(E17)Asp → Val]: A new variant

A new hemoglobin variant found in a mother and her child was characterized by column chromatography of the tryptic hydrolysate of the aminoethylated, glycinamidated -chain, followed by chymotryptic digestion of the abnormal T-9 peptide and amino acid analyses. It was shown to be _{2 2} 73(E17) Asp Val and named Hb Mobile.This work was supported in part by Research Grants AM0780 and AM13173 from the National Institute for Arthritis and Metabolic Disease.     

Functional properties of the newly observed γ-chain fetal hemoglobin variant Hb F-Monserrato-Sassari (HBG2:c.280T > C) or [γ93 (F9) Cys → Arg]

Background

HbF-Monserrato-Sassari is a newly discovered abnormal fetal hemoglobin observed in an apparently normal newborn baby during a hemoglobinopathies survey at birth in North Sardinian population.

Methods

Electrophoretic analysis of the cord blood lysate evidenced for an abnormal tetramer due to a mutated fetal globin chain. Electrospray ionisation-mass spectrometry and gene sequencing were used to identify the mutation. Oxygen binding ability of the variant Hb was determined.

Results

Sequencing of the γ globin genes revealed the TGT → CGT transition at codon 93 in one of the two ^Gγ genes, which leads to the Arg for Cys amino acid replacement at position 9 of the F α-helix. The amino acid substitution was confirmed by mass spectrometric analysis of the globin chains. Since modifications or substitutions at position β93 are known to affect the arrangement of a salt bridge at the α1β2 sliding contacts that are crucial for subunit cooperativity, the functional properties of the variant were studied to evaluate the effect of the replacement at the same position in the γ globin chain. With respect to normal HbF, the variant showed a significant increase in oxygen affinity and a slight decrease of both Bohr effect and cooperativity.

General significance

Result indicates a key role of the Cys γ93 residue for subunit cooperativity in the T → R transition of the HbF tetramer. Substitutions at the F9 position of the ^Gγ globin may result in stabilization of the high affinity R-state of the Hb tetramer. Because of the loss of Cys γ93 residue, this variant is considered to be potentially compromised in nitric oxide transport.     

Hb Riesa or β93 (F9) Cys→Ser, a new electrophoretically silent haemoglobin variant interfering with haemoglobin A1c measurement

A new β variant was found in a German diabetic patient whose blood samples appeared to contain 45% Hb A(1c) using Bio-Rad Variant V-II A1c-analyzer but 7.6% on boronate affinity chromatography. Structural studies using, HPLC, mass spectrometry, and the genomic DNA analysis revealed a new substitution in which the cysteine residue at position β93 was replaced by serine. The variant was named Hb Riesa or β93 (F9) Cys→Ser and accounted for 54.3% of the total haemoglobin. This suggests that the protein-synthesis processes for the mutant could be slightly more promoted than those of the wild-type. Hb Riesa is clinically and electrophoretically silent.     

Hemoglobin calais [β 76 (E20) Ala → pro]: a hemoglobin variant with decreased intrinsic oxygen affinity

Hb Calais [β 76 (E20) Ala → Pro] is a new human hemoglobin variant displaying a decreased oxygen affinity. The only electrophoretical difference with Hb A was a slight more acidic isoelectric point. A 2-fold decrease in the oxygen affinity was found by equilibrium measurements performed in a suspension of intact red blood cells and in the lysate. It was confirmed by kinetic studies of the purified abnormal hemoglobin. The rte of methamoglobin formation at 37°C of Hb Calais was also increased realtive to Hb A. The mechanism by which the Pro for Ala substitution of an external residue in the β-chains results in these profound functional abnormalities is nuclear. Subtle changes at the heme pocket, at a distance from teh mutation, may be a plausible explanation for the effects observed.     

Hemoglobin roanne [α94(G1) asp å glu]: a variant of the α1β2 interface with an unexpected high oxygen affinity

In hemoglobin (Hb) Roanne, the aspartate residue α 94(G1) is replaced by a glutamic acid. This residue plays a key role in the structural changes affecting the α1β2 contact area during the deoxy- to oxy-state transition in the hemoglobin molecule. Aspartate α94(G1) is involved in several contacts both in the deoxy- and oxy-structures. The most important of those is a hydrogen bond with asparagine β102 (G4), stabilizing the oxygenated structure. Alteration of this contact usually leads to a decrease in oxygen affinity. Hb Roanne is the first example in which an increased oxygen affinity was found as a result of a structural modification at this position. Functional data suggested that the mechanisms responsible for this altered property are a destabilisation of the T-structure and a modification of the allosteric equilibrium.     

Hemoglobin tilburg: α2-ß2 73 (E 17) Asp→Gly: A new hemoglobin with reduced oxygen affinity

A new hemoglobin variant has been found in a Dutch Caucasian girl and detected also in members of three generations of her family. This variant is characterized by the substitution of an aspartic acid at position 73 (E 17) of the ß-chain with a glycine residue. Hemoglobin Tilburg makes up to 42% of the total hemoglobin in the blood of the proposita, it is stable at the isopropanol test, and not associated with significant hematological abnormalities in heterozygous carriers. The oxygen dissociation curve of the purified variant, carried out at different pH values, shows a definite reduction of the affinity for oxygen and a normal alkaline Bohr effect. Three more hemoglobins with a single amino acid substitution at the same site have been previously described: Hb Korle-Bu (Asp→Asn), Hb Mobile (Asp→Val) and Hb Vancouver (Asp→Tyr). In all these proteins the affinity for oxygen is lowered to an extent which is variable and characteristic of each mutant. In this paper we discuss the possible mechanism responsible for the abnormal behaviour of hemoglobins substituted at ß 73.     

Preparation of (1 → 3)-β-d-glucan oligosaccharides by hydrolysis of curdlan with commercial α-amylase

Water soluble (1 → 3)-β-d-glucan oligosaccharides were prepared by hydrolyzing curdlan with α-amylase. The hydrolysis process was monitored by the DE values of the hydrolysates. Under the optimized conditions (pH, 5.98; temperature, 55.92 °C; α-amylase amount, 31.94 mg α-amylase/500 mL of reaction mixture containing 5 g curdlan; reaction time, 30 min), maximum DE value (15.62%) was obtained. The resulting products were composed of (1 → 3)-β-d-glucan oligosaccharides of DP 2-9. The hydrolysates were filtered, concentrated to ∼20% (w/v), and precipitated with 5 volumes of ethanol, which were then freeze dried to yield a water soluble powder. The (1 → 3)-β-d-glucan oligosaccharides content of the product and the yield were 97.7% and 97.6% (w/w), respectively.     

A family of lanthanide-containing molecular open frameworks with high porosity: [Ln(abdc)(Habdc), nH2O]∞ with Ln = La-Eu and 8 ? n ? 11

Reactions in water between the di-sodium salt of amino terepthalic acid (C₈H₃NO₄Na₂) and a lanthanide chloride lead to a family of 3D-coordination polymers with general chemical formula [Ln(C₈H₃NO₄)(C₈H₄NO₄), O]_∞ where Ln = La-Eu (except Pm) and 8 ? n ? 11. All these compounds are isostructural. High quality single crystals of [Ln(C₈H₃NO₄)(C₈H₄NO₄), nH₂O]_∞ with Ln = La-Sm (except Pm) and 8 ? n ? 11 have been obtained by slow diffusion in agar-agar gels. The crystal structure has been solved for the Nd-containing compound. This compound crystallizes in the cubic system, space group Ia-3 (no. 206) with a = 26.8056(5) Å. The crystal structure can be described as the juxtaposition of large channels with square cross-section.The channels are filled by highly disordered crystallization water molecules. The dehydration of the compounds by freeze-drying is possible and most of the crystallization water molecules can be removed without destruction of the molecular skeleton. The partially dehydrated compounds have general chemical formula [Ln(abdc)(Habdc), 2H₂O]_∞ with Ln = La-Eu except Pm. The porosity of the Nd-containing compound has been estimated by computational methods to 2170 m² g⁻¹. This dehydrated compound reversibly binds water when exposed to wet atmosphere restoring the initial hydrated phase.     

Hb Natal or α2(minus Tyr-Arg)β2: A high oxygen affinity α chain variant with a deleted carboxy-terminus resulting from a TAC → TAA (Tyr → terminating codon) mutation in codon α140

The discovery is reported of a fast-moving α chain variant (Hb Natal) which is characterized by a shortened α polypeptide chain because of the deletion of the Tyr-Arg carboxy-terminal residues. Through amplification of appropriate segments of DNA and hybridization with synthetic oligonucleotide probes, it was possible to detect a C → A mutation in codon 140 of the α₂ globin gene, which causes a change in the codon for tyrosine to a terminating codon. Hb Natal or α₂(minus Tyr-Arg)β₂ has a high affinity for oxygen without a Bohr effect and heme-heme interaction. These results provide direct evidence for the importance of the tyrosine residue at α140 in the oxygenation-deoxygenation process.     

Hb Villaverde [β 89 (F5) Ser → Thr]: the structural modification of an intrasubunit contact is responsible for a high oxygen affinity

Hb Villaverde [β89 (F5) Ser → Thr], identified in a Spanish patient, is a new human hemoglobin variant, electrophoretically silent, responsible for a severe erythrocytosis. This abnormal hemoglobin displays a very high oxygen affinity and a markedly reduced cooperativity that is partly restored in the presence of IHP. Determination of the structural abnormality was achieved on a mixture of the normal and abnormal β-chains. After isolation of the abnormal tryptic peptide by RP-HPLC, its sequence was determined by mass spectrometry. The structural abnormality disturbs the intrasubunit interaction between helices F and H and, thus, may weaken the C-terminal bonds of the deoxy conformation and the heme contacts of several hydrophobic residues. Hb Villaverbe demonstrates that this intrasubunit contact between helices F and H is essential for the cohesion of the hemoglobin molecule.     

Synthesis, crystal structures, and spectroscopic characterization of the neutral monomeric tetrahedral [M(Diap)2(OAc)2] · H2O complexes (M = Zn,Cd; Diap = 1,3-diazepane-2-thione; OAc = acetate) with N-H?O and O-H?O intra- and intermolecular hydrogen bonding interactions

The title complexes, [M(Diap)₂(OAc)₂] · H₂O (M = Zn,Cd; Diap = 1,3-diazepane-2-thione; OAc = acetate) with an MO₂S₂ configuration, have been characterized by X-ray crystallography as well as FT-IR, ¹H and ¹³C NMR spectroscopy. In these complexes, the metal atoms lie in a pseudo-tetrahedral environment and are coordinated by the thione sulfur atoms of two neutral 1,3-diazepane-2-thione ligands and one oxygen atom from each of two monodentate acetate anions. In both complexes, there are two intramolecular N-H?O hydrogen bonds, each being between one NH group of a Diap ligand and the uncoordinated O atom of an OAc ligand. The water molecule is also involved in hydrogen bonds, as an acceptor and as a donor twice, linking together three symmetry-related complexes. The Cd complex undergoes a structural phase transition from a monoclinic form at 150 K with Z′ = 2 to a smaller monoclinic cell at room temperature with Z′ = 1 without loss of crystallinity. The Zn complex does not exhibit an equivalent phase transition, and at 150 K is isostructural with the room-temperature form of the Cd complex. All three crystallographically independent molecules found for the Cd complex (two at low temperature and one at room temperature) have essentially the same structure except for small changes in the conformations of the ligands. Tetrahedral coordination with monodentate carboxylate ligands is common for Zn complexes of this kind, but is unusual for Cd complexes, and is the result of the bulky Diap ligands.     

Unusual packing of ET molecules caused by π-π stacking interactions with TRISPHAT molecules in two [ET][TRISPHAT] salts (ET = bis(ethylenedithio)tetrathiafulvalene, TRISPHAT = (tris(tetrachlorobenzenediolato)phosphate(V)))

The synthesis, structure and physical properties of two new radical salts formed with the organic donor bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) and a racemic mixture of the chiral anion (tris(tetrachlorobenzenediolato)phosphate(V)) (TRISPHAT) are reported. The structure of the salts (ET)₄[TRISPHAT]₄ · 3.5H₂O (1) and (ET)(TRISPHAT) · CH₂Cl₂ · CH₃CN (2) has been solved by X-ray single crystal diffraction. Unusual packings of ET molecules are obtained in the two structures. The electrical properties indicate that both compounds are insulators. This is in agreement with the isolation of the ET molecules and their complete ionization. On the other hand, the anisotropy of the ESR lines has been studied by Q-band ESR spectra.     

Hemoglobin Okayama [β-2 (NA 2) His → Gln]: A new ‘silent’ hemoglobin variant with substituted amino acid residue at the 2,3-diphosphoglycerate binding site

A new ‘silent’ abnormal hemoglobin, Hb Okayama [β2 (NA 2) His → Gln], happened to be discovered in a diabetic Japanese female living in Okayama Prefecture, Japan, in the course of glyco-Hb measurement of the blood samples of diabetic patients. This variant did not differ from Hb A by conventional electrophoretic tests. Only the isoelectric focusing on PAG plate for the determination of glyco-Hb and the cation exchanger chromatography were successful in the separation of this abnormal variant from Hb A and glyco-Hb. Functional study of the whole blood demonstrated a slight increase of oxygen affinity.     

Layered iron(II) spin crossover complex constructed by NH?Br hydrogen bonds with 2 K wide thermal hysteresis, [FeH3L]Br·CF3SO3 (H3L = tris[2-(((2-methylimidazol-4-yl)methylidene)amino)ethyl]amine)

A series of compounds [Fe^IIH₃L^Me]Br·Y·nMeOH ( (1), (2), (3), (4); n = 0 or 1) were synthesized, where H₃L^Me is a hexadentate N₆ tripodal ligand of the neutral form, tris[2-(((2-methylimidazol-4-yl)methylidene)amino)ethyl]amine, and their structures and magnetic properties were investigated. The compounds 1−3 with counter anions , , and contain methanol as a crystal solvent, and show no SCO behaviors, while the corresponding Cl⁻ compounds have no crystal solvent and show a variety of SCO behaviors. The compound [Fe^IIH₃L^Me]Br·CF₃SO₃ (4) has no crystal solvent and has isomorphous structure to the Cl⁻ compounds, and shows an abrupt spin transition between the HS (S = 2) and LS (S = 0) states with a hysteresis about 2 K and large frozen-in effect below 72 K. The T_1/2↑ and T_1/2↓ values are 98 and 96 K, whose values are higher than those of corresponding Cl⁻ compound about 15 K and the width of hysteresis is narrower than that of corresponding Cl⁻ compound about 2 K. The crystal structures of 4 were determined at 296 and 93 K, where the crystal system and space group showed no change between these temperatures. The structures at both temperatures have a same 2D layered structure, which is composed of NH?Br⁻ hydrogen bonds between the Br⁻ ion and the imidazole NH groups of three neighboring cations [Fe^IIH₃L^Me]²⁺. This network structure is the same as that of corresponding Cl⁻ compound. The 600 nm light irradiation at 5 K induced the LIESST effect.     

Bidimensional self-assembling of [Hg(RPhNNNPhR′)2] (R = acetyl, R′ = F) through metal-η-arene π-interactions and non classical C-H?O bonding: Synthesis and X-ray characterization of a bis diaryl asymmetric-substituted triazenide complex polymer of Hg(II)

Deprotonated 3-(2-fluorophenyl)-1-(4-acetylphenyl)triazene reacts with Hg(CH₃COO)₂ in tetrahydrofuran to give light yellow crystals of [Hg^II(RPhNNNPhR′)₂]_n (R = acetyl, R′ = F). The new polymeric triazenide complex of Hg(II) belongs to the monoclinic space group C2/c. The lattice of [Hg^II(RPhNNNPhR′)₂]_n can be viewed as a bidimensional assembly of planar tectons [Hg^II(RPhNNNPhR′)₂], occurring through metallocene alike Hg(II)-η²,η²-arene π-interactions along the crystallographic axis b and non classical C-H?O bonding along the axis a.     

A new hydrated phase of cobalt(II) oxalate: crystal structure, thermal behavior and magnetic properties of {[Co(μ-ox)(H2O)2] · 2H2O}n

A cobalt-oxalato complex of formula {[Co(μ-ox)(H₂O)₂] · 2H₂O}_n (1) (ox=oxalate dianion) has been prepared and characterized by X-ray diffraction analysis, thermoanalytical techniques and variable temperature susceptibility measurements. The compound crystallizes in the triclinic space group with cell parameters: a=6.627(1), b=8.715(2), c=11.106(2) Å, α=69.86(1), β=83.45(1), γ=72.33(1)°. Its crystal structure consists of crystallization water molecules and one-dimensional linear chains of [Co(H₂O)₂]²⁺ units linked by bis-bidentate oxalato ligands. These structural units are held together by an extensive network of hydrogen bonds. The magnetic properties show the occurrence of antiferromagnetic interactions between the metal centers.     

Synthesis of (β-phenylethynyl)-gem-diphenyltrifluorocyclotriphosphazene and its reaction with RCpCo(PPh3)2 [R = MeOC(O)]

Reaction of gem-diphenyltetrafluorocyclotriphosphazene with in situ generated lithiated phenylacetylene resulted in the formation of the first example of a gem-diphenyltrifluorophosphazene based alkyne (β-phenylethynyl)-gem-diphenyltrifluorocyclotriphosphazene (NPPh₂)(NPF₂)[NP(F)CCPh] 1. Reaction of this alkyne with η⁵-(MeOC(O)C₅H₄)Co(PPh₃)₂ resulted in the formation of a CpCo stabilized cyclobutadiene complex [η⁵-carbomethoxycyclopentadienyl][η⁴-1,3-bis(gem-diphenyltrifluorocyclotriphosphazenyl)-2,4-diphenylcyclobutadiene]cobalt 2, having two gem-diphenyltrifluorophosphazene moieties trans to each other on the cyclobutadiene ring. The reaction also yielded two structural isomers of the PPh₃ stabilized cobaltacyclopentadiene compounds 3 and 4 having gem diphenyl trifluorophosphazene moieties present in the 2,4 and 2,5 positions of the metallacycle. The reaction in addition yielded a novel spirocyclic phosphazacyclopentadiene compound bound to a CpCo unit in the η⁴-mode 5. All the compounds were characterized by ¹H, ¹³C, ³¹P and ¹⁹F NMR spectroscopy and compounds 2, 3 and 5 were also structurally characterized by X-ray crystallography.     

A randomized,controlled trial of interferon-β-1a (Avonex<Superscript>®</Superscript>) in patients with rheumatoid arthritis: a pilot study [ISRCTN03626626]

The objective of this study was to evaluate the safety and possible efficacy of IFN-β-1a for the treatment of patients with rheumatoid arthritis (RA). Twenty-two patients with active RA were enrolled in a phase II randomized, double-blind, placebo-controlled trial of 30 μg IFN-β-1a by weekly self-injection for 24 weeks. The primary outcome of the study was safety. Secondary outcomes included the proportion of patients achieving an American College of Rheumatology (ACR) 20 response at 24 weeks. There were no significant differences in adverse events reported in the two groups. Fewer than 20% of patients in each arm of the study achieved an ACR 20 response at 24 weeks (P = 0.71). Sixty-nine percent of patients receiving IFN-β and 67% receiving placebo terminated the study early, most of them secondary to a perceived lack of efficacy. Overall, IFN-β-1a had a safety profile similar to that of placebo. There were no significant differences in the proportion of patients achieving an ACR 20 response between the two groups.     

Association of TGF-β1 − 509 C/T, 29 C/T and 788 C/T gene polymorphisms with chronic periodontitis: A case–control study

The aim of this study was to investigate the possible association between TGF-β1 − 509 C/T (rs1800469), 29 C/T (Prol10Leu, rs1800470) and 788 C/T (Thr263Ile, rs1800472) gene polymorphisms and chronic periodontitis (CP) in a sample of Iranian population. This case–control study was conducted on 100 CP patients and 100 healthy unrelated, age-, sex-, and ethnicity-matched. Genotyping was performed by tetra amplification refractory mutation system-polymerase chain reaction (T-ARMS-PCR) technique. Our findings showed that there was a significant difference between the groups regarding TGF-β1 29 C/T (rs1800470) polymorphism (χ2 = 23.23, P < 0.0001). The CT and TT genotypes increased the risk of CP in comparison with the CC genotype (OR = 4.42, 95% CI = 2.16–9.06, P < 0.001 and OR = 5.84, 95% CI = 2.32–14.71, P < 0.001, respectively). The T allele increased the risk of CP (OR = 2.50, 95% CI = 1.66–3.74, P < 0.001) in comparison with C allele. No significant association was found among the groups regarding − 509 C/T and 788 C/T variants of TGF-β1 gene. This study shows that TGF-β1 29 C/T polymorphism, but not − 509 C/T and 788 C/T polymorphisms, may contribute to the development of CP in a sample of Iranian population. Further studies with larger sample sizes and different ethnicities are needed to validate our findings.