Application of an automatic oxygenation technique to analysis of oxygen equilibrium curves for hemoglobinopathic red cells and functional screening of clinically important hemoglobinopathies

Redox proteomic identification of 4-hydroxy-2-nonenal-modified brain proteins in amnestic mild cognitive impairment: insight into the role of lipid peroxidation in the progression and pathogenesis of Alzheimer's disease

Numerous investigations point to the importance of oxidative imbalance in mediating AD pathogenesis. Accumulated evidence indicates that lipid peroxidation is an early event during the evolution of the disease and occurs in patients with mild cognitive impairment (MCI). Because MCI represents a condition of increased risk for Alzheimer's disease (AD), early detection of disease markers is under investigation. Previously we showed that HNE-modified proteins, markers of lipid peroxidation, are elevated in MCI hippocampus and inferior parietal lobule compared to controls. Using a redox proteomic approach, we now report the identity of 11 HNE-modified proteins that had significantly elevated HNE levels in MCI patients compared with controls that span both brain regions: Neuropolypeptide h3, carbonyl reductase (NADPH), alpha-enolase, lactate dehydrogenase B, phosphoglycerate kinase, heat shock protein 70, ATP synthase alpha chain, pyruvate kinase, actin, elongation factor Tu, and translation initiation factor alpha. The enzyme activities of lactate dehydrogenase, ATP synthase, and pyruvate kinase were decreased in MCI subjects compared with controls, suggesting a direct correlation between oxidative damage and impaired enzyme activity. We suggest that impairment of target proteins through the production of HNE adducts leads to protein dysfunction and eventually neuronal death, thus contributing to the biological events that may lead MCI patients to progress to AD.

A new Spanish family with Hb Louisville

The clinical, hematological, and biochemical characteristics of a new family with heterozygous hemoglobin (Hb) Louisville are described. The family showed a decrease in both oxygen affinity and cooperativity with the normal Bohr effect. This family has the greatest number of affected members reported to date. Among the descendants, two first cousins (III-10 and III-11), both of whom are affected by the heterozygous trait of Hb Louisville, had had three abortions of undetermined causes.

Functional properties of Hb Pasadena, alpha 2 beta 2 75(E 19) Leu replaced by Arg

Functional properties of Hb Pasadena (beta 75[E19]Leu replaced by Arg) as well as correlations of its structure-function relationships with those of normal hemoglobin are presented. The homeotropic and heterotropic properties of the isolated variant were investigated by automatic recording oxygen equilibrium analysis. These studies indicate an increase of 02 affinity but normal cooperativity. The decrease of 02 affinity in response to organic phosphate (DPG and IHP) was found to be normal. However, the cooperativity of Hb Pasadena is less affected by IHP than is that of Hb A. The alkaline Bohr effect was found to be somewhat decreased, although the temperature effect is nearly normal. The autoxidation rate is increased by a factor of nearly 2 compared to normal. These observations are consistent with the conclusion that the beta (E19)75 leucyl hydrophobic residue of Hb A associates with beta (A8)11 Val, beta (A12)15 Trp and beta (H11)133 Val to form a hydrophobic cluster between the A, E and H helics which thereby stabilizes the heme of the beta chain in the deoxy ferrous state. The experimental results also suggest that the amino acid substitution in Hb Pasadena mainly disrupts the interior conformation of the beta subunit without affecting subunit interfaces. Thus it is predicted that Hb Pasadena should have a normal crystal structure in either the liganded (R) or unliganded (T) state. Its increased 02 affinity can be explained partially by a decrease of proton binding and partially by a shift of the R:T equilibrium towards the R conformation.

Structural analysis of human hemoglobin variants with field desorption mass spectrometry

Tryptic hydrolyzates of normal and abnormal human globin chains were analyzed with mass spectrometry, using field desorption ionization technique. All the peptides, including core peptides, were detected as protonated molecular ions in field desorption mass spectra. Since the technique makes it possible to determine the mass number of each peptide, it is very useful for structural analysis of human hemoglobin variants, even those with electrophoretically and chromatographically silent mutations.

Hemoglobin Miyashiro (beta 23[B5] val substituting for gly) an electrophoretically silent variant discovered by the isopropanol test

A new unstable hemoglobin was discovered in a Japanese boy without any signs of hemolytic disease during screening of patients by the isopropanol test. The abnormal hemoglobin was found in three generations. This slightly unstable hemoglobin could not be separated from Hb A by electrophoresis. All carriers showed an increased whole blood oxygen affinity. Structural studies demonstrated a previously unreported amino acid substitution, beta 23[B5] valine substituting for glycine. This new unstable variant has been named Hb Miyashiro.