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J Thillet

Publications and source records attributed to J Thillet.

72 records · Page 4Linked to original sources
PubMed1977

Structural and functional studies of hemoglobin J Cala-bria: beta64 (E8) Gly leads to Asp.

A hemoglobin of high electrophoretic mobility was detected in a French male suffering from an acute leukemia; this hemoglobin was also present in his family. The variant was unstable and possessed an abnormal beta chain, in which a glycyl residue in position 64 (E8) was replaced by an aspartyl residue. This variant constitutes a new case of Hb J Calabria. Since the substituted E8 residue is in close spatial contact with that at B6, it was of interest to compare the properties of Hb J Calabria with those of other hemoglobins bearing substitutions at the same site.

Adult↗
PubMed1977

Hemoglobin Pontoise alpha63 Ala replaced by Asp(E12). A new fast moving variant.

The present report describes structural and functional studies of a new hemoglobin variant, Hb J Pontoise. This abnormal hemoglobin was discovered in a 36 year old Spanish man. The substitution of alpha63 (E12) Ala replaced by Asp is situated at an external site and appears to have no influence on the function of the hemoglobin. Nevertheless, it presents some instability in vitro, as demonstrated by the isopropanol test. This instability could partially explain the low percentage of the abnormal hemoglobin in the hemolysate (12%), since its rate of synthesis was normal.

Adult↗
PubMed1976

Hemoglobin Dakar = Hb Grady: demonstration by a new approach to the analysis of the tryptic core region of the alpha chain and oxygen equilibrium properties.

Preliminary studies have suggested that in Hb Dakar, histidine alpha112 was substituted by a glutamine. A re-investigation on this hemoglobin is presented in this report. A structural study has been performed using a new approach to analyse the tryptic core region of the human hemoglobin alpha chain. After tryptic digestion of the aminoethylated alpha chain, a secondary digestion of the tryptic core was carried out with chymotrypsin and with another protease, thermolysin. Analyses of the chymotryptic and thermolytic peptides indicated that the structure of Hb Dakar was identical to that of Hb Grady previously described by Huisman et al. who showed the insertion of three amino acid residues in position alpha115 or alpha118. The insertion, which was localized near two residues involved in the alpha1beta1 contact, did not produce a dissociation into dimers. Functional studies demonstrated a a slightly increased oxygen affinity, a lowered cooperativity and a normal Bohr effect. The low amount of the abnormal hemoglobin (8%) may in part be explained by a slight instability of the molecule.

Amino Acid Sequence↗
PubMed1976

Electron paramagnetic resonance of Hb St Louis beta28 (B10) Leu replaced by Gln.

Hemoglobin St Louis beta28 (B10) Leu replaced by Gln is a new mutant which occurs as a natural valency hybrid (alpha2beta+2), or hemoglobin M (Cohen-Solal, M., Seligmann, M., Thillet, J. and Rosa, J. (1973) FEBS Lett. 33, 37-41). The electron paramagnetic resonance (EPR) spectrum of native Hb St Louis at pH 6.2 shows a mixture of three species. Two are high spin, one with tetragonal symmetry, like Hb+ A, the other with rhombic distortion. The third is a low-spin form corresponding to a hemichrome with the distal (E7) histidine as the sixth ligand of the ferric iron. The hemichrome is also found in red blood cells. After oxidation to the alpha+2beta+2 form, three EPR species are seen. Surprisingly, there remains only one high-spin signal, with almost tetragonal symmetry. Besides the low-spin hemichrome, a hydroxy signal is observed even at pH 6.2. These observations imply interactions between the alpha and beta hemes.

Electron Spin Resonance Spectroscopy↗
PubMed1976

Functional and physicochemical studies of hemoglobin St. Louis beta 28 (B10) Leu replaced by Gln: a variant with ferric beta heme iron.

Studies have been performed on a 20-yr-old man exhibiting methemoglobinemia and a severe hemolytic anemia involving formation of Heinz bodies. This condition was due to an abnormal Hb present in the red cells of the proband: Hb St. Louis, beta 28 (B10) replaced by Gln, whose structural characteristics have been previously reported. This unstable Hb represented 30% of the total and was isolated by starch block electrophoresis at pH 8.6. Electrophoretic and spectral studies showed Hb St. Louis to be a valency hybird, alpha 2 beta 2+. The presence of hemichrome in this Hb was detected by electron paramagnetic resonance studies. During this study, an electrophoretic technique was developed that allows study of the mobility of hemichrome. Oxygen equilibria performed on purified Hb St. Louis revealed a high oxygen affinity and a markedly reduced cooperativity. The Bohr effect was normal, but the interaction of this hemoglobin with 2,3-diphosphoglycerate was decreased. The oxidation rate of Hb St. Louis was normal. Hb St. Louis was completely reduced by dithionite and ferrous citrate, and the functional properties of this reduced form were normal. In contrast, Hb St. Louis was only partially reduced by diaphorase. The mechanism of the oxidation of Hb St. Louis therefore appears to differ markedly from that postulated for other Hbs M.

Adult↗
PubMed1975

Haemoglobin Saki alpha 2 beta 2 14 Leu-Pro(a11) structure and function.

The characterization of haemoglobin Saki alpha 2 beta 2 14 Leu-Pro(a11) is described. This new mutation is unique since it only induces modification of the stability of the molecule. In vitro precipitation of haemoglobin Saki upon heat or in the presence of chemicals is compared to the stability of haemoglobin A and haemoglobin S.

Adult↗
PubMedDate not supplied

[Hemoglobin J. Broussais alpha-2 90 Lys leads to Asn beta-2A (FG2) discovered in a Martinique family. Comparison of several analytical technics].

We report a new case of hemoglobin J. Broussais, present in its heterozygote form in a seven year old child from Martinque. The structural characteristics of this abnormal hemoglobin have been compared by three methods: 1. By analytical and preparative finger-printing on silica gel thin layer plates after tryptic digestion. 2. By a programmed separation of tryptic peptides on various ion exchange resins. 3. And by automatic sequencing of the peptides obtained following CNBr cleavage and separation by gel filtration chromatography. The functional behaviour of this hemoglobin was not modified by the substitution of an Asn for a Lys residue at position 90, although its presence induced slight hematological disorders in the patient. Abnormal hemoglobins which have been identified in Martinique and Guadeloupe are reviewed.

Amino Acid Sequence↗
PubMedDate not supplied

[A new case of hemoglobin G Georgia (author's transl)].

A new case of hemoglobin G Georgia (alpha95 Pro yields Leu) is described in a portuguese patient with lymph node tuberculosis. The patient had a slight anaemia with haemolytic crises and moderate splenomegaly. The electrophoretic mobility of this unstable, abnormal haemoglobin was slower than that of Hb S. The percentage of the major (alpha2 G beta2) and the minor (alpha2 G delta2) abnormal components was determined by DEAE-sephadex chromatography and was 18% and 1% respectively. Structural analysis showed the replacement of a proline residue in position 95 (G) in the alpha chain by a leucine residue. This residue alpha 95 interferes with the alpha 1-bêta 2 contact. Functional studies have shown an increased oxygen affinity, a reduced hem-hem interaction and a normal Bohr effect.

Anemia, Hemolytic↗
PubMedDate not supplied

[Clinical, structural and functional studies of HbG Philadelphia detected in a Moroccan newborn].

Hb G Philadelphia (alpha68 Asn leads to Lys) is widely distributed in black people but is uncommon in North-Africa. Only one case has been previously described in an Arab immigrant. The latter and our propositus originated from North-East morocco. Hb G alpha Philadelphia is stable. The abnormal hemoglobin represented 28% of total hemoglobin in the hemolysate of the propositus, a 7 month old child. At birth, 4 fractions were detected on electrophoresis: Hb A, Hb F, Hb G Philadelphia, which migrated like Hb S, and a mutant alpha2Ggamma2. The oxygen affinity of Hb G Philadelphia was slightly elevated. Cooperativity and Bohr effect were normal. The abnormal hemoglobin was also detected in the father of the propositus in the heterozygote state: its clinical and hematological data were normal. No evidence of thalassemia trait was found in the family. The percentage of abnormal hemoglobin obtained in the propositus and his father is in accordance with the presence of two loci for the alpha chain on the homologous chromosome.

Electrophoresis, Cellulose Acetate↗