Characterization of acatalasemia detected in two Hungarian sisters

Catalase enzyme mutations and their association with diseases

Enzyme catalase seems to be the main regulator of hydrogen peroxide metabolism. Hydrogen peroxide at high concentrations is a toxic agent, while at low concentrations it appears to modulate some physiological processes such as signaling in cell proliferation, apoptosis, carbohydrate metabolism, and platelet activation. Benign catalase gene mutations of 5' noncoding region (15) and intron 1 (4) have no effect on catalase activity and are not associated with disease. Catalase gene mutations have been detected in association with diabetes mellitus, hypertension, and vitiligo. Decreases in catalase activity in patients with tumors is more likely to be due to decreased enzyme synthesis rather than to catalase mutations.Acatalasemia, the inherited deficiency of catalase has been detected in 11 countries. Its clinical features might be oral gangrene, altered lipid, carbohydrate, homocysteine metabolism and the increased risk of diabetes mellitus. The Japanese, Swiss, and Hungarian types of acatalasemia display differences in biochemical and genetic aspects. However, there are only limited reports on the syndrome causing these mutations. These data show that acatalasemia may be a syndrome with clinical, biochemical, genetic characteristics rather than just a simple enzyme deficiency.

A new type of inherited catalase deficiencies: its characterization and comparison to the Japanese and Swiss type of acatalasemia

Thirteen Hungarian families that exhibited inherited catalase deficiencies have been detected. Differences between the deficiencies reported from Hungary and the previously reported Swiss acatalasemia were characterized using biochemical analysis of the catalase proteins. Molecular biological methods were used to compare the previously reported types of catalase deficiencies in Japan and the Hungarian deficiencies. Three mutations (a GA insertion in exon 2, a G insertion in exon 2, and a T to G substitution in intron 7) are responsible for decreased catalase activity in 7 of the 13 Hungarian kindreds; the other 6 families have not yet been characterized. These are not the mutations observed in Japan. Changes in lipid and carbohydrate metabolism and the high incidence (12.7%) of diabetes mellitus in the Hungarian kindreds suggest that individuals with inherited catalase deficiency are at risk of atherosclerosis and diabetes mellitus. The Hungarian subjects were detected during screening of a large population for catalase activity; no overt disease state was associated with the deficiencies. We hypothesize that the increased risk of disease may be due to prolonged exposure to elevated levels of blood hydrogen peroxide due to the lack of normal removal of hydrogen peroxide by blood catalase.

Anovel catalase mutation (a GA insertion) causes the Hungarian type of acatalasemia

Acatalasemia, a deficiency of enzyme catalase, is an autosomal recessive syndrome with an incidence of 5:106 in Hungary. We have examined the first Hungarian acatalasemic family for the disease-causing mutation. All exons of the catalase gene were screened by PCR-SSCP, PCR-heteroduplex, and nucleotide sequence analysis. The heteroduplex formation detected in exon 2 was verified by nucleotide sequence analysis. We found a GA insertion at nucleotide position 138, increasing the GA repeat number from 4 to 5. This GA insertion caused a frameshift in the amino acid sequence from position 68 to 133 and generated a TGA terminating codon at amino acid position 134. This truncated protein lacks the essential amino acid (histidine 74) in the active center. This finding can explain the decreased blood catalase activity in the Hungarian acatalasemic family.

Purification and characterization of liver catalase in acatalasemic beagle dog: comparison with normal dog liver catalase

Catalase from acatalasemic dog liver was purified to homogeneity and its properties were compared with those of normal dog liver catalase. The purified acatalasemic and normal dog liver catalases were found to have the same molecular weight (230,000 Da) and isoelectric point (pI: 6.0-6.2) and both enzymes contained four hematins per molecule. The catalytic activity of catalase from acatalasemic dog was normal. Furthermore, there was no difference between the acatalasemic and normal dog catalases in the binding affinity to NADPH (apparent Kd: 0.11-0.12 microM) and in the sensitivity to oxidative stress by hydrogen peroxide, the normal substrate of catalase. The acatalasemic dog enzyme was stable only in a narrow pH range (pH 6-9) although the normal enzyme was stable in a wide pH range (pH 4-10). Acatalasemic dog liver catalase also showed a slight low thermal stability at 37 degrees C and the heat-lability was remarkable at 45 degrees C, compared to the normal dog enzyme. These results indicated that the acatalasemic dog catalase is catalytically normal although it is associated with an unstable molecular structure.

Further genetic heterogeneity in acatalasemia

A T-deletion at position 10 of exon 4 for catalase gene was reported as a novel mutation, causing a new genetic type of acatalasemia in Japan. This mutation, destroying a Hinf1 recognition site, was searched for in Hungarian acatalasemic (2) and hypocatalasemic (22) patients and in controls (27) by Hinf1 digestion and sequence analyses of a 203 bp polymerase chain reaction (PCR) product containing the entire exon 4. The Hinf1 polymorphism did not reveal any difference between controls and hypocatalasemic as well as acatalasemic patients. These results were confirmed by sequence analyses showing the T nucleotide for the two acatalasemic and for one unrelated hypocatalasemic patient, as well as for two controls. These findings represent further evidence that acatalasemia is heterogeneous at the DNA level.

Polymorphism of 5' of the catalase gene in Hungarian acatalasemia and hypocatalasemia

The amplified fragment length polymorphism of Hinf1 on the promoter region of the catalase gene in Hungarian acatalasemic and hypocatalasemic patients yielded three different patterns with five bands in total. The sequence analyses revealed A-to-T, C-to-A, and C-to-T mutations at positions -21, -20, and -18 upstream of the translational initiation site. The -21 A-to-T mutations were more frequent in acatalasemic and hypocatalasemic patients (36/2) than in controls (18/14). This mutation had been detected in Japanese acatalasemic patients while the other two are novel mutations. Two extra bands in the Hinf1 pattern are due to star-like activity that cleaved a G/ATTT sequence at position -4 to 0 upstream of the initiation site.

Reference ranges of normal blood catalase activity and levels in familial hypocatalasemia in Hungary

In 1756 healthy individuals the mean and S.D. values of blood catalase activity were 111.3 +/- 16.5 MU/l with lower blood catalase for females (107.7 +/- 14.4 MU/l, n = 880) than for males (117.9 +/- 16.8 MU/l, n = 876) while the ratios of blood catalase activity to blood hemoglobin concentration were not different (0.841 +/- 0.107 MU/g versus 0.849 +/- 0.119 MU/g). The decrease of blood catalase with age was greater in males (b = -0.084 MU/l year) than in females (b = -0.016 MU/l year). The screening of 3300 healthy citizens for hypocatalasemia yielded six families (0.18%), and three families were identified out of 1630 clinic patients. These nine families revealed 37 hypocatalasemic patients with 57.5 +/- 11.7 MU/l mean and S.D. of blood catalase activity. Similarly to the Japanese and the Hungarian actalasemic patients, the electrophoretic mobilities of catalase in erythrocytes of hypocatalasemic patients were indistinguishable from that of healthy controls.

Genetic heterogeneity in acatalasemia

203 bp long products containing exon 4 and its junctions from the catalase gene were generated by polymerase chain reaction (PCR). These products were analyzed by single strand conformational polymorphism (SSCP), hetero-duplex formation and nucleotide sequencing. No polymorphism was detected when the Hungarian acatalasemic sisters, their family members and normocatalasemic controls were analyzed. Sequence analyses did not show the G to A point mutation at position 5 of intron 4. This splicing mutation characterizes the Japanese-type of acatalasemia.

Hungarian hereditary acatalasemia and hypocatalasemia are not associated with chronic hemolysis

Two Hungarian acatalasemic and eight hypocatalasemic patients revealed normal erythropoesis. Contrary to their decreased defence system against the toxic hydrogen peroxide, the biochemical tests (serum catalase, serum hemoglobin, serum lactate dehydrogenase (LDH) ratio of LDH1 and LDH2 isoenzymes and serum haptoglobin) excluded hemolysis. The normal activity of glutathione peroxidase and the decreased catalase activity could prevent the lysis of the erythrocytes. In the presence of extremely high levels of hydrogen peroxide acute hemolysis may not be excluded; therefore, follow-up of these patients is required.

Ionic adsorption of catalase on bioskin: kinetic and ultrastructural studies

Bioskin is a natural polymer produced by Acetobacter xylinum and several yeasts in culture. It contains glucosamine and N-acetyl galactosamine which promote ionic adsorption of catalase at the adequate pH value. High values of ionic strength are required to enzyme desorption. Adsorption of catalase on bioskin fibers has been visualized by scanning electron microscopy associated to a dispersion X-ray analyzer. At low enzyme density, the affinity of the immobilized catalase for hydrogen peroxide was 30% lower than that of the free enzyme. This affinity decreased dramatically at higher density of immobilized enzyme and could not be increased by agitation of the enzyme reaction mixture. Immobilized catalase retains about 70% of its initial activity after 16 d storage, whereas soluble enzyme is completely inactivated after 3 d at room temperature. The haeme group of catalase is not protected after immobilization since it is accessible to both EDTA and phloroglucinol, chelating agents which inactivate catalase by removing the iron atom from the haeme group.