Functional studies of two new abnormal hemoglobins with their mutation located at intersubunit contacts: Hb Hotel Dieu beta99 (G1) Asp replaced by Gly and Hb Pitie Salpetriere beta34 (B16) Val replaced by Phe.

The functional properties of two new abnormal hemoglobins with high oxygen affinity were studied. Hb Hôtel Dieu beta99 (G1) Asp replaced by Gly is situated in the alpha1beta2 contact. Hb Pitié Salpétrière beta34 (B16) Val replaced by Phe is situated in the alpha1beta1 contact. Both hemoglobins exhibited similar functional properties with a 10-fold increased oxygen affinity, a decreased cooperativity, a decreased Bohr effect and a normal or slightly decreased 2,3-diphosphoglycerate effect. The structure-function relationship is discussed in the light of these results.

Hemoglobin J Cairo: beta 65 (E9) Lys leads to Gln, A new hemoglobin variant discovered in an Egyptian family.

The present report describes clinical, hematological and biochemical studies of a 27-year old Egyptian woman in whom a fast moving Hb variant was found. The abnormal Hb constituted 48% of the total erythrocyte Hb of the propositus and her father. Structural studies demonstrated that in the abnormal Hb lysine beta 65 is replaced by glutamine. The new Hb mutant is designated hemoglobin J Cairo beta 65 (E9) Lys leads to Gln. This substitution results in only a moderate decrease in cooperativity. No evidence of Hb instability was found. A slight anemic state has been observed in the propositus since she reached adolescence.

Hemoglobin Pitie-Salpetriere beta 34 (B16) Val replaced by Phe. A new high oxygen affinity variant associated with familial erythrocytosis.

Hemoglobin Pitie-Salpetriere was detected by routine isoelectric focusing. It moved up on isoelectric focusing between hemoglobin A and hemoglobin F, near Hb F. On cellulose acetate strips at pH 8.6, it moved as hemoglobin A. This new variant exhibits a high oxygen affinity associated with familial erythrocytosis. The valine residue in position beta 34 has been replaced by a phenylalanine residue. This residue is involved in the alpha 1 beta 1 contact.

Hb Marseille [alpha 2 beta 2 N methionyl-2 (NA2) His----Pro]: a new beta chain variant having an extended N-terminus.

A new abnormal hemoglobin was found in a diabetic Maltese woman by citrate agar electrophoresis. This variant was undetectable by isoelectric focusing. No hematological abnormalities were observed. The structural analysis included isolation of the abnormal beta chain, high pressure liquid chromatography of the corresponding tryptic peptides and then microsequencing of the abnormal T1. These procedures revealed a double abnormality: the presence of a methionyl residue extending the NH2 terminus and a histidine to proline substitution in position NA2.

A new silent hemoglobin variant in a black family from French West Indies, hemoglobin Le Lamentin alpha 20 His replaced by Gln.

A new abnormal hemoglobin Hb Le Lamentin alpha 20 (B1) His replaced by Gln was discovered during a survey of cord blood from the French West Indies (Martinique). This variant displays an electrophoretic pattern similar to that of Hb A but can be isolated by isoelectric focusing (IEF) and Biorex 70 chromatography. Family studies showed the presence of this hemoglobin variant in the father and in two of his three children. Hematological data from the carriers were normal.

Hemoglobin Roseau-Pointe a Pitre alpha 2 beta 2(90) (F6) Glu----Gly: a new hemoglobin variant with slight instability and low oxygen affinity.

A Dominican neonate carrying a new abnormal hemoglobin, hemoglobin Roseau Pointe-à-Pitre alpha 2 beta 2(90)(F6) Glu----Gly, was detected in Guadeloupe during application of a cord blood screening program. This variant behaved in isoelectrofocusing as an Hb D, and displayed instability and low whole blood oxygen affinity. In the affected family it was present, either isolated, or in association with a beta+ thalassemia trait.

Structural study of hemoglobin Hazebrouck, beta 38(C4)Thr----Pro. A new abnormal hemoglobin with instability and low oxygen affinity.

A new beta-variant has been detected and structurally defined in a French male, with a life-long history of hemolytic anemia. This variant is moderately unstable and has a low oxygen affinity. The abnormal hemoglobin was not detected by standard electrophoretic procedures. It moved slightly slower than Hb A during isoelectric focusing (IEF). Two minor fractions were also seen; the first migrated just cathodal to Hb F, as did partially oxidized Hb A or hemichrome derivatives of some unstable hemoglobins; the second in the position of free alpha-chains. The abnormal beta-chain was readily separated from both beta A- and alpha A-chains by acid-urea-Triton globin chain electrophoresis. Structural study was conducted simultaneously by fingerprinting and high-performance liquid chromatography (HPLC) of tryptic peptides. A new mutation beta 38(C4)Thr----Pro was found, which was named Hb Hazebrouck.

Structural study of hemoglobin Knossos, beta 27 (B9) Ala leads to Ser. A new abnormal hemoglobin present as a silent beta-thalassemia.

A new electrophoretically silent hemoglobin variant is described that produces the classical phenotype of beta thalassemic intermedia in association with beta thalassemia trait. This variant has the expression of a silent beta thalassemia trait. The abnormal hemoglobin was detected by acid-urea-Triton-acrylamide electrophoresis and further demonstrated by isoelectric focusing. The amount of the variant in carrier is approximately 30% of the total hemoglobin. No instability was found. Absence of hemoglobin A in the propositus blood facilitated structural studies. Peptides maps were normal but analysis of individual peptide spots showed an Ala leads to Ser substitution in the beta T3. This variant has been previously called Hb Knossos (beta 27 (B9) Ala leads to Ser).

Critical role of human bisphosphoglycerate mutase Cys22 in the phosphatase activator-binding site.

The enzymatic activities catalyzed by bisphosphoglycerate mutase (BPGM, EC 5.4.2.4) have been shown to occur at a unique active site, with distinct binding sites for diphosphoglycerates and monophosphoglycerates. The physiological phosphatase activator (2-phosphoglycolate) binds to BPGM at an undetermined site. BPGM variants were constructed by site-directed mutagenesis of three amino acid residues in the active site to identify residues specifically involved in the binding of the monophosphoglycerates and 2-phosphoglycolate. Substitution of Cys22 by functionally conservative residues, Thr or Ser, caused a great decrease in 2-phosphoglycolate-stimulated phosphatase activity and in the Ka value of the activator, whereas it caused no change in other catalytic activities or in the Km values of 2,3-diphosphoglycerate (2,3-DPG) and glycerate 3-phosphate (3-PG, EC 1.1.1.12), indicating that Cys22 is specifically involved either directly or indirectly in 2-phosphoglycolate binding. Kinetic experiments showed that the Ka of the cofactor and the Km of 3-PG were affected by the substitution of Ser23 indicating that this residue is necessary for the fixation of both 3-PG and 2-phosphoglycolate. The R89K variant has previously been shown to have a modified Km value for monophosphoglycerates, however, its affinity for 2-phosphoglycolate is unaltered, suggesting that Arg89 is specifically involved in monophosphoglycerates binding. CD spectroscopic studies of substrates and cofactor binding showed that 2,3-DPG induced structural modifications of normal and mutated enzymes which could be due to protein phosphorylation. Addition of 2-phosphoglycolate to phosphorylated proteins with normal affinity for the cofactor produced spectra with the same characteristics as unphosphorylated species. In summary, monophosphoglycerates and 2-phosphoglycolate have partially distinct binding sites in human BPGM. The specific implication of the Cys22 residue in 2-phosphoglycolate binding is of great significance in the design of analogs of therapeutic benefit.

Hemoglobin Hotel-Dieu beta 99 Asp replaced by Gly (g1). A new abnormal hemoglobin with high oxygen affinity.

Hemoglobin Hotel-Dieu was detected by isoelectric focusing during investigation of a patient who had erythrocytosis. This variant migrates on cellulose acetate electrophoresis to a cathodic position relative to Hb F. In hemoglobin Hotel-Dieu, aspartic acid is substituted by glycine in position 99 of the beta chain. As in other abnormal hemoglobins in which substitution of this residue has occurred, Hb Hotel-Dieu exhibits a high oxygen affinity and is associated with familial erythrocytosis.

[Biochemical characterization and study of the sensitivity to Plasmodium falciparum infection. Apropos of a case of double CN Baltimore hemoglobinopathy discovered in Senegal]. / Caractérisation biochimique et étude de la sensibilité à l'infection par Plasmodium falciparum. A propos d'un cas de double hémoglobinose CN Baltimore découvert au Sénégal.

The discovery of a double CNBalt hemoglobinopathy allowed the authors, after a family background investigation, to study the possible biological effects linked to that dual heterozygoty and to look for a protection against Plasmodium falciparum infections. It hasn't been possible to make evident any protection.

Hb Tunis [alpha 2 beta 2 124 (H2)Pro----Ser], a new beta chain variant identified by HPLC.

During a routine hematological investigation of a child from Tunis, a silent hemoglobin variant was discovered by isoelectric-focusing. This variant was not detectable by conventional electrophoretic methods, had normal stability, expression, and oxygen affinity, and did not produce any clinical symptoms. This new variant beta 124(H2)Pro----Ser was named Hb Tunis.

Hemoglobin Brest [beta 127 (H5)Gln----Lys] a new unstable human hemoglobin variant located at the alpha 1 beta 1 interface with specific electrophoretic behavior.

Hb Brest [beta 127 (H5)Gln----Lys] is a new unstable variant located at the alpha 1 beta 1 interface at the same position as Hb Complutense [beta 127(H5)Gln----Glu]. In each of these, the substitution produces a distinct alteration in charge, yet both variants move with Hb A in conventional electrophoresis. This peculiar electrophoretical behavior may be due to the molecular position of the modified residue, which is deeply buried inside the tetramer.

Hemoglobin Köln occurring in association with a beta zero thalassemia: hematologic and functional consequences.

Hemoglobin (Hb) Köln-beta zero thalassemia compound heterozygosity was discovered in a young Greek patient. This gave us the unique opportunity for studying the functional properties of this unstable high-oxygen affinity hemoglobin variant in red cells containing almost pure Hb Köln. The red cells of the proposita exhibit morphological alterations and hematologic indices corresponding to the presence of an unstable Hb and beta thalassemia. Globin chain synthesis confirmed the association with a beta zero thalassemia gene. Oxygen-binding curves for these cells were biphasic, indicating the presence of both heme-saturated and of approximately 20% of non-cooperative Hb Köln. The major component exhibits an increased oxygen affinity, reduced cooperativeness, and normal alkaline Bohr effect. The 35-year-old proposita is active, has not been splenectomized, and has not been transfused in several years.

A recombinant bisphosphoglycerate mutase variant with acid phosphatase homology degrades 2,3-diphosphoglycerate.

To date no definite and undisputed treatment has been found for sickle cell anemia, which is characterized by polymerization of a deoxygenated hemoglobin mutant (HbS) giving rise to deformed erythrocytes and vasoocclusive complications. Since the erythrocyte glycerate 2,3-bisphosphate (2,3-DPG) has been shown to facilitate this polymerization, one therapeutic approach would be to decrease the intraerythrocytic level of 2,3-DPG by increasing the phosphatase activity of the bisphosphoglycerate mutase (BPGM; 3-phospho-D-glycerate 1,2-phosphomutase, EC 5.4.2.4). For this purpose, we have investigated the role of Gly-13, which is located in the active site sequence Arg9-His10-Gly11-Glu12-Gly13 in human BPGM. This sequence is similar to the Arg-His-Gly-Xaa-Arg* sequence of the distantly related acid phosphatases, which catalyze as BPGM similar phosphoryl transfers but to a greater extent. We hypothesized that the conserved Arg* residue in acid phosphatase sequences facilitates the phosphoryl transfer. Consequently, in human BPGM, we replaced by site-directed mutagenesis the corresponding amino acid residue Gly13 with an Arg or a Lys. In another experiment, we replaced Gly13 with Ser, the amino acid present at the corresponding position of the homologous yeast phosphoglycerate mutase (D-phosphoglycerate 2,3-phosphomutase, EC 5.4.2.1). Mutation of Gly13 to Ser did not modify the synthase activity, whereas the mutase and the phosphatase were 2-fold increased or decreased, respectively. However, replacing Gly13 with Arg enhanced phosphatase activity 28.6-fold, whereas synthase and mutase activities were 10-fold decreased. The presence of a Lys in position 13 gave rise to a smaller increase in phosphatase activity (6.5-fold) but an identical decrease in synthase and mutase activities. Taken together these results support the hypothesis that a positively charged amino acid residue in position 13, especially Arg, greatly activates the phosphoryl transfer to water. These results also provide elements for locating the conserved Arg* residue in the active site of acid phosphatases and facilitating the phosphoryl transfer. The implications for genetic therapy of sickle cell disease are discussed.