Glucose-6-phosphate dehydrogenase deficiency inhibits in vitro growth of Plasmodium falciparum

Glucose-6-phosphate dehydrogenase (G6PD; EC 1.1.1.49)-deficient red blood cells from male hemizygotes and female heterozygotes from the island of Sardinia were studied for their ability to support growth in vitro of the malaria-causing organism Plasmodium falciparum. Parasite growth was approximately one-third of normal in both hemi- and heterozygotes for G6PD deficiency. In Sardinians with the beta 0-thalassemia trait, parasite growth was normal except when G6PD deficiency occurred together with the thalassemia trait. The data support the hypothesis that G6PD deficiency may confer a selective advantage in a malarious area; the female heterozygote may be at a particular advantage because resistance to malaria equals that of male hemizygotes, but the risk of fatal hemolysis may be less. However, more female heterozygotes must be studied to confirm this hypothesis. No protective effect of beta 0-thalassemia trait could be demonstrated in vitro.

Purification and properties of diamine oxidase from Euphorbia latex

A diamine oxidase has been purified to homogeneity from the latex of an herbaceous shrub, Euphorbia characias. This enzyme has a relative molecular mass of 144,000 and is composed of two identical subunits. It contain two Cu(II) and two carbonyl-like groups per dimer. The purified enzyme is pink and shows a broad absorption in the visible region centered at 480 nm, which is modified by the addition of phenylhydrazine or semicarbazide. The electron paramagnetic resonance spectrum is typical of copper(II) in a tetragonal symmetry. This enzyme oxidizes putrescine and cadaverine at fairly high rate and, less efficiently a few related compounds, but not histamine, spermine or spermidine.

Diamine oxidase from pig kidney: new purification method and amino acid composition

Several methods for the isolation of apparently homogeneous pig kidney diamine oxidase have been reported in recent years (1-7), but these procedures allow to obtain only little amounts of material making very difficult the study of the molecular properties of the enzyme. Drawing useful indication from the purification procedures previously reported, we were able to set up a new method which allows to obtain homogeneous enzyme samples in high yield and with good reproducibility. This procedure allowed to determine with greater accuracy the molecular weight of the enzyme that resulted to be 170,000 daltons by gel chromatography and 145,000 by ultracentrifuge. The enzyme is composed of two apparently identical subunits and contains two copper atoms per dimer. The amino acid composition of the protein has been also worked out and found similar to those already reported for other copper dependent amine oxidases. Pig kidney diamine oxidase is a glycoprotein containing about 20% sugars by weight.

Oxidation of meso-diaminosuccinic acid, a possible natural substrate for D-aspartate oxidase

meso-Diaminosuccinic acid, a natural antagonist of aspartic acid, is a good substrate for beef kidney D-aspartate oxidase. The oxygen consumption and the ammonia production are in good agreement with the stoichiometry of a typical oxidative deamination. The deamination involves only one of the two amino groups of diaminosuccinate, and is followed by decarboxylation of the first reaction product, 2-amino-3-oxosuccinic acid. By condensation of the compounds thus originating from this latter, pyrazine 2,5-dicarboxylic acid and pyrazine 2,6-dicarboxylic acid are formed. DL-Diaminosuccinic acid is not oxidized by D-aspartate oxidase, nor does it inhibit the enzyme activity.

Heat-denaturation of pig kidney diamine oxidase: effect of arcaine

Pig kidney diamine oxidase is protected against heat denaturation by the presence of inhibitors like tetramethylene diguanine (arcaine). In the presence of inhibitor the enzyme retains its full activity even after 30 min. incubation at 60 degrees C. This inhibitor binds to the enzyme inducing small but significant absorption changes in the near uv spectrum. Temperature dependence of intrinsic fluorescence yield is different in the presence and absence of arcaine, indicating a conformational stabilizing effect of this inhibitor.

[Glycosylated hemoglobins and erythrocyte 2,3-diphosphoglycerate in diabetes mellitus]

Investigations carried out on 43 diabetic not ketoacidotic patients (32 women and 11 men) showed that the percentage of glycosylated hemoglobins (GHb) is significantly (p less than 0.01) inversely related to the intra-erythrocytic concentration of 2,3-DPG and to the calculated P50. Preliminary data from a prospective study suggest that the inverse relationship could be referred to the degree of control of the disease. In poorly controlled diabetes, where at the highest percentages of GHb the lowest levels of 2,3-DPG are found, less oxigen can be delivered to peripheral tissues.

Genetic variation in the quantitative levels of an NADP (H)-binding protein (FX) in human erythrocytes

FX is a red cell NADP(H)-binding protein that has been well defined biochemically and immunologically but whose function is still unknown. Preliminary data indicated that the levels of this protein are significantly increased in hemizygotes, heterozygotes, and homozygotes for the G6PD Mediterranean mutant, thus raising the question of whether or not the individual variation in FX levels is more or less directly influenced by X-linked genes. The present study, based on a large series of population and family data collected in Sardinia, confirms unequivocally the above mentioned interaction, but shows at the same time that the variances in FX levels "between sibships" are 2-3 times larger than those "within sibships," when the analysis is done separately for the G6PD-normal or the G6PD-deficient sibs. From the comparison of the interclass and intraclass correlation coefficients, it appears that about 60% of the total variation of FX is of genetic origin. Moreover, the FX levels of children, analyzed in a pairwise manner, were found to be more positively correlated with those of their fathers (r = 0.39) than with those of their maternal grandfathers (0.20). This latter finding obviously favors the conclusion that "autosomal" rather than "X-linked" genes are involved in the determination of the FX levels.

[Behavior of plasma triglycerides and cholesterol in diabetic patients]

34 diabetic patients (24 females and 10 males) were studied and hypertriglyceridemia was found only in females. Obesity seems to be the most important factor determining hypertriglyceridemia and hypercholesterolemia. No correlation was found between glycosylated haemoglobin and triglycerides or cholesterol levels. Only a little correlation was found between fasting plasma glucose and triglycerides levels.

[Erythrocytic 2-3-diphosphoglycerate in diabetes mellitus]

Red cell 2-3 DPG concentration in diabetes mellitus has been found to be equal to normal. Red cell 2-3 DPG seems to be related to Hb concentration. There is an appreciable scatter of 2-3 DPG among healthy males and healthy females. Female diabetics have a red cell 2-3 DPG like male diabetics despite a significative lower Hb concentration. However, the conflicting data reported on the amount of 2-3 DPG in diabetic red cells could be referred to an unequal arrangement of males and females in control subjects and diabetics.

X-mapping in man: evidence against measurable linkage between anhidrotic ectodermal dysplasia and G6PD deficiency

A Sardinian kindred segregating for X-linked anhidrotic ectodermal dysplasia (AED), glucose-6-phosphate dehydrogenase (G6PD) deficiency of Mediterranean type, and Xga blood antigen provides evidence against a measurable linkage between the loci for AED and G6PD. Moreover, from the segregation of the combined phenotypes in four scorable sons from two triple heterozygotes with phase known, it seems highly probable that the AED locus is nearer to the centromere than is the G6PD locus.

Additional pedigree supporting the frequent origin of XXYY from consecutive meiotic non-disjunction in paternal gametogenesis

A 48,XXYY Sardinian patient, born to a 46,XX mother heterozygous for the Gd Mediterranean mutant, and to a 46,XY father hemizygous for the same mutant, was found to have a mosaic distribution of G6PD(+) and G6PD(-) peripheral red blood cells. The most likely interpretation of this finding is that the propositus is an additional example of an XXYY zygote derived from a consecutive meiotic non-disjunction during paternal gametogenesis.

Synthesis and chromatographic properties of Se-carboxymethyl-selenohomocysteamine (2-carboxymethyl, 3-aminopropyl selenide)

Details are reported for the synthesis of Se-carboxymethylselenohomocysteamine from selenohomocysteamine and monochloroacetic acid. Data on its behaviour on paper and ion-exchange chromatography are also reported, which allow its identification.

[Anti-islet cell antibodies in insulin-dependent diabetics. Preliminary study]

Anti-islet cell cytoplasm antibodies (ICA) were noted in the serum of insulin-dependent diabetics, but not in subjects with insulin-independent forms. These antibodies seem to represent an immunological marker for two forms of the disease, one in which ICA appears shortly after onset and later disappears, and another ("autoimmune") form in which ICA is detectable for long periods and persists along with other signs of alteration of the immune system.

Triplo-X constitution of mother explains apparent occurrence of two recombinants in sibship segregating at two closely X-linked loci (G6PD and deutan)

Two male sibs believed to be examples of meiotic recombinants between the closely linked loci for G6PD deficiency of Mediterranean type and severe deutan color blindness proved to be simple segregants of a triplo-X mother of genotype d--GdMediterranean/d+GdMediterranean/d+GdB. This finding suggests that in Sardinia the linkage between the two loci under consideration may be tighter than previously assumed.

Essential arginine residues in beef kidney D-aspartate oxidase (a preliminary report)

Partially purified D-aspartate oxidase from beef kidney has been tested in the presence of butanedione or phenylglyoxal, which specifically modify the arginine molecule. The results obtained clearly indicate that arginine residues are involved in the binding of the substrate to the active site of the enzyme.

Linkage disequilibrium for two X-linked genes in Sardinia and its bearing on the statistical mapping of the human X chromosome

The distribution of four X-linked mutants (G6PD, Deutan, Protan and Xg) among lowland and once highly malarial populations of Sardinia discloses a clear-cut example of linkage disequiligrium between two of them (G6PD and Protan). In the same populations the distribution of G6PD-deficiency versus colorblindness of the Deutan type and the Xg blood-group is not significantly different from that expected at equilibrium. These data suggest indirectly that the loci for G6PD and Protan may be nearer to one another than those for G6PD and Deutan.

Synthesis and chromatographic properties of selenazolidine-4-carboxylic acid (selenaproline)

Details are reported for the synthesis of DL-selenazolidine-4-carboxylic acid starting from DL-selenocystine and formaldehyde. Some chemical reactions and the paper and ion-exchange chromatographic behaviour of selenazolidine carboxylic acid in comparison with thiazolidine-4-carboxylic acid are described.

Chromatographic separation of selenohypotaurine, selenotaurine, selenohomohypotaurine and selenohomotaurine

By either paper or ion-exchange chromatography the two seleninic compounds selenohypotaurine and selenohomohypotaurine, and the two selenonic compounds selenotaurine and selenohomotaurine may be all separated from each other. On paper chromatography seleninic derivatives may be separated from the corresponding sulphinic compounds, while selenonic compounds show RF values similar to those of the corresponding sulphonic derivatives. These two latter types of compounds may be differentiated, however, since selenonic compounds liberate iodine from HI, while sulphonic compounds do not. Also by automated ion-exchange chromatography seleninic derivatives are well separated from the analogous sulphinic compounds, while selenonic compounds are eluted together with the corresponding sulphonic compounds.

Hair root versus red cell individual phenotype in Sardinian heterozygotes for G6PD deficiency (Mediterranean type)

G6PD activity was assayed in 20 Sardinian heterozygotes for G6PD deficiency and related to that of LDH and MDH. One of these heterozygotes showed a deficient phenotype in all her follicles, while the remaining 19 had different proportions of deficient, intermediate, and normal follicles. This is in accordance with a previous estimate. Because of the broad fiducial limits at the 5% level and because of some developmental considerations, this value cannot be interpreted as indicative of the number of primordial cells for scalp epidermis at the time of X-chromosome inactivation, as previously stated. The assay of single hair follicles is, however, a very valuable tool for establishing the role of cell selection in the same or in a different tissue, like peripheral blood.