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Biomedical subjects

D L Jue

Publications and source records attributed to D L Jue.

At least 55 records · Page 3Linked to original sources

Hemoglobin Evanston: alpha 14(A12) Trp leads to Arg. A variant hemoglobin associated with alpha-thalassemia-2.

Hb Evanston (alpha 14 Trp leads to Arg) was detected on cellulose acetate at pH 8.4 as a band with an electrophoretic mobility similar to that of Hb S. In addition, a band migrating cathodic to Hb A2 suggested the presence of a variant Hb A2 with a substitution in the alpha-chain, a fact that was later confirmed by structural analysis. An unusual feature of Hb Evanston is its low percentage; less than 10% occurs in the hemolysate. Studies indicate that the variant is not unstable, but there appears to be a defect in globin-chain synthesis. Gene mapping also shows that it is associated with the alpha-thalassemia-2 gene. The variant has high oxygen affinity with normal cooperativity and a normal Bohr effect. The combination of Hb Evanston with alpha-thalassemia-2 produced anemia in this black family.

Female↗

Hemoglobin Cheverly: an unstable hemoglobin associated with chronic mild anemia.

The evaluation of a family with chronic mild anemia led to the identification of a new unstable hemoglobin (Hemoglobin Cheverly). Modest anemia and reticulocytosis, normal to slightly increased mean corpuscular volume (MCV), and normal mean corpuscular hemoglobin concentration (MCHC) were present in the affected family members. Electrophoresis of blood samples on cellulose acetate and on citrate agar revealed normal patterns. Globin chain analysis and isoelectric focusing data were also normal. After incubation for 3 h at 41 degrees C, Heinz bodies were detected in 95-100% of erythrocytes from affected individuals. Positive heat and isopropanol tests confirmed the initial observation of the Heinz body preparation and indicated that an unstable hemoglobin was present. Structural analysis showed an amino acid substitution of Phe-Ser at position 45 (CD4) in the beta chain. Hemoglobin Cheverly has a reduced affinity for oxygen and a reduced Bohr effect, properties that can be rationalized on the basis of the x-ray crystallographic structure of normal hemoglobin. Despite structural and functional similarities between Hb Cheverly and Hb Hammersmith, beta 42 (CD1) Phe-Ser, the clinical manifestations of Hb Cheverly are mild in contrast to the severe disease observed with Hb Hammersmith. Reasons for the apparently silent clinical expression of Hb Cheverly are not known. We discuss the implications of unstable hemoglobins in the evaluation of chronic anemia in pediatric patients.

Anemia↗

Hemoglobin Queens: alpha 34 (B15) Leu-Arg structural and functional properties and its association with Hb E.

Hemoglobin Queens: alpha 34 (B15) Leu-Arg was found in association with Hb E in a Vietnamese boy. The observed microcytosis and hypochromia were due to Hb E, which also occurred in other members of this family. The functional properties of Hb Queens in the absence and presence of allosteric effectors were normal. The abnormal hemoglobins appear to be unrelated to the hyperbilirubinemia that was observed at birth.

Amino Acids↗

Hemoglobin connecticut (beta 21 (B3) Asp leads to Gly): a hemoglobin variant with low oxygen affinity.

Electrophoretic analysis of a hemolysate from a young man undergoing a routine physical examination revealed an abnormal hemoglobin with a mobility similar to Hb S on cellulose acetate (pH, 8.4). This new variant, designated Hb Connecticut, was found in three generations of a family of Polish descent. Several individuals possessing the variant exhibited mild anemia. Structural analysis of the abnormal beta-chain indicated that the amino acid substitution was at position 21 (B3), and involved the replacement of aspartic acid with glycine. Oxygen dissociation studies revealed low oxygen affinity. The alkaline Bohr effect and the degree of cooperativity were unchanged. Analysis of the crystal structure of the variant suggested that the low oxygen affinity was due to the possible disruption of salt bridges between aspartic acid 21(B3) and lysines 61(ES) and 65(E9), changes that could lead to steric interference in oxygen binding.

Adolescent↗

Hemoglobin Cubujuqui (alpha 141 Arg-Ser): functional consequences of the alteration of the C-terminus of the alpha chain of hemoglobin.

Hemoglobin Cubujuqui (1) was detected in several members of a Mexican-American family. Structural analysis of this hemoglobin indicated that the carboxyl terminal arginine at position 141 in the alpha chain had been replaced by serine. This residue is critical not only in stabilizing the deoxy or T conformation by electrostatic interactions, but it is also involved in the Bohr effect through its linkage with Val 1 alpha of the opposite alpha chain in the tetramer. The variant exhibits high affinity for oxygen that is associated with destabilization of the deoxy conformation, and reduced cooperativity. The pH and the chloride sensitivity of the variant are also reduced, as compared to Hb A.

Amino Acid Sequence↗

Hemoglobin Tampa:beta 79 (EF3) aspartic acid replaced by tyrosine.

Hemoglobin Tampa was detected in a 6-year-old male caucasian who is homozygous for this variant hemoglobin. The variant hemoglobin has an electrophoretic mobility between Hb F and Hb S on cellulose acetate (pH 8.5) and a mobility between Hb S and Hb C on citrate agar (pH 6.0). In acid buffer globin chain analysis revealed an abnormal beta chain with a mobility between the beta A and beta S chains, and in alkaline buffer the mobility of the chain was at the beta S position. Structural characterization of the variant beta chain indicates that aspartic acid is replaced with tyrosine at position 79, the site of a previously reported mutation, Asp replaced by Gly (Hb Hsi-Tsou). The clinical histories of the available family members including the homozygous propositus appear to be unremarkable.

Amino Acids↗

Hemoglobin variants and methods used for their characterization during 7 years of screening at the Center for Disease Control.

During 7 years of screening for hemoglobin variants, over 75 rare variants have been characterized. Of these, 18 were described for the first time. This report presents tabulated data regarding the structural and functional defects that were observed, information on the ethnic origin, and other special properties exhibited by these variants. The strategy and procedures for characterizing these variants are also summarized.

Centers for Disease Control and Prevention, U.S.↗

Hemoglobin Dunn: alpha 6 (A4) aspartic acid replaced by asparagine.

Hemoglobin Dunn, alpha 6 (A4) Asp leads to Asn was found in a 39-year-old black woman and her daughter. The hematological data on the propositus were normal and there were no apparent clinical or pathological findings associated with this abnormal hemoglobin. The structural characterization of this variant is described.

Adult↗

Hemoglobin S Travis: a sickling hemoglobin with two amino acid substitutions [beta6(A3)glutamic acid leads to valine and beta142 (h20) alanine leads to valine).

Hb S Travis is a previously undescribed sickling hemoglobin with two amino acid substitutions in the beta chain: beta6 Glu leads to Val and beta142 Ala leads to Val. The beta6 Glu leads to Val mutation imparts to Hb S Travis the characteristic properties of sickling hemoglobin, namely its association with erythrocyte sickling, the insolubility of the hemoglobin in the reduced form, and a minimum gelling concentration value identical to Hb S. Unlike Hb S, Hb S Travis exhibits an increased oxygen affinity and a decreased affinity for 2,3-bisphosphoglycerate and inositol hexakisphosphate. In addition, the variant hemoglobin's tendency to autoxidize and its mechanical precipitability suggest that there are conformational differences between Hb S and Hb S Travis.

Alanine↗

Hemoglobin Tarrant: alpha126(H9) Asp leads to Asn. A new hemoglobin variant in the alpha1beta1 contact region showing high oxygen affinity and reduced cooperativity.

Hemoglobin (Hb) Tarrant was detected by its electrophoretic mobility on cellulose acetate (pH 8.4) and citrate agar (pH 6.2). On cellulose acetate it moved as a band between hemoglobins F and S, and on citrate agar as a band at hemoglobin S. The test for solubility in 2 M phosphate buffer with Na2S2O4 was negative. The new variant has a substitution of asparagine for aspartic acid in position 126 of the alpha-chain, one of the sites involved in the alpha1beta1 contact. Furthermore, in deoxyhemoglobin aspartic acid 126 of each alpha chain also forms a non-covalent electrostatic salt bridge with arginine 141 of the corresponding alpha chain (Perutz, M. F. and Ten Eyck, L. F. (1972) Cold Spring Harbor Symp. Quant. Biol. 36, 295-310 and Perutz, M. F. (1970) Nature 228, 726-739). As a consequence of this substitution in hemoglobin Tarrant, the deoxy conformation or T state is destabilized because these two bridges cannot be formed. This condition is reflected in high oxygen affinity and low cooperativity.

Amino Acid Sequence↗

Hemoglobin Fannin-Lubbock [alpha2 beta 2 119 (GH2) Gly replaced by Asp]. A new hemoglobin variant at the alpha1 beta 1 contact.

Hemoglobin Fannin-Lubbock was found in a 9-year-old Mexican-American female. The abnormal hemoglobin was detected as a fast-moving variant by electrophoresis on cellulose acetate at pH 8.4. Structural analysis indicated a substitution in the beta-chain of aspartic acid for glycine at position 119, a position involved in the alpha1beta1 contact of the hemoglobin tetramer. This contact between unlike chains is larger and undergoes a smaller shift during the process of oxygenation and deoxygenation that the alpha1beta2 contact (Perutz, M.F., Muirhead, H., Cox, J.M. and Goaman, L.C.G. (1968) Nature 219, 131-139). Mutations in this contact tend to cause slight or no changes in functional behavior. Apart from a mild anemia, the propositus did not exhibit any obvious clinical symptoms.

Amino Acids↗

Hemoglobin Providence. A human hemoglobin variant occurring in two forms in vivo.

Hemoglobin Providence Asn and Hemoglobin Providence Asp are two abnormal hemoglobins which apparently arise from a single genetic change that substitutes asparagine for lysine at position 82 (EF6) in the beta chain of human hemoglobin. The second form appears to be thr result of a partial in vivo deamidation of the asparagine situated at position beta 82. Cellulose acetate and citrate agar electrophoresis of hemolysates from patients with this abnormality shows three bands. Globin chain electrophoresis at acid and alkaline pH shows three beta chains. These three chains correspond to the normal beta A chain and two abnormal beta chains. Sequence analysis indicates that the two abnormal chains differ from beta A at only position beta 82. In the two abnormal chains, the residue which is normally lysine is substituted either by asparagine or by aspartic acid. These substitutions are notable because beta 82 lysine is one of the residues involved in 2,3-diphosphoglycerate binding. Additionally, beta 82 lysine is typically invariant in hemoglobin beta chain sequences. Sequence data on the two forms of Hemoglobin Providence are given in this paper. The functional properties of these two forms are described in the next paper.

Adult↗