Lens glycosidases in human and bovine species. I. Quantitative studies.
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Age Factors↗
Biomedical subjects
J C Dreyfus
Publications and source records attributed to J C Dreyfus.
Accuracy of portein synthesis and in vitro aging. Search for altered enzymes in senescent cultured cells from human livers.
The authors have looked for altered proteins in senescent cultured cells from adult liver. Four enzymes (phosphoglycerate kinase, M2 type pyruvate kinase, glucose phosphate isomerase and glucose-6-phosphate dehydrogenase) have been studied by immunological and enzymatic titration and electrofocusing. In addition, heat stability of glucose-6-phosphate dehydrogenase (G6PD) was appraised in cell crude extracts and in partially purified preparations. Enzymatic aactivity as well as immunological reactivity of the four enzymes studied were identical 16 lines in phase II and in 13 lines in phase III. Electrofocusing pattern of the enzymes from 'young cells' was identical to the ones from 'old cells'. Finally, G6PD from old cells seemed to be more unstable than G6PD from young cells when studied in crude extracts. These differences, however, disappeared as G6PD was partially purified from old or young cultured cells. Consequently, no evidence of altered protein, either missynthesized or posttranslationally modified, was found in the senescent cultured cells studied. Moreover, this work indicated that the modification of heat stability of G6PD from old cells was not due to the enzyme molecule itself but rather to the cell medium.
Aging↗
Possible molecular mechanisms of ageing.
While the error theory of ageing has attracted most interest in recent times it cannot yet be regarded as being demonstrated. Posttranslational modifications of proteins genetic theory appears loical but has little in vivo evidence to prove it. Basic mechanisms of ageing probably involve the interaction of several processes.
Aging↗
[Human myopathy and animal muscular dystrophy].
Two hereditary muscular dystrophies similar to human progressive muscular dystrophy (P.M.D. Duchenne type) have been isolated in animals, one in mouse, the other in chicken. The decrease in the activity of glycogenolytic enzymes is similar to that observed in denervated muscle. Isozymic fetal types for several muscular enzymes have been observed as well in chicken as in man, but this fetal type may also be found in neurogenic atrophy. The release in circulation of muscle enzymes seems more specific. But the origin of the genetic lesion is still unknown. We describe here the three different theories about this problem: i.e. neurogenic, vascular, or myogenic. This last theory implies a trouble of membrane permeability.
Adenosine Triphosphate↗
Characterization of a variant of beta-hexosaminidase: "hexosaminidase Paris".
A family (father and daughter) was found with a deficiency of hexosaminidase (HEX A and HEX B). Residual HEX A activity was about 30% of usual heterozygotes with very little HEX B activity. Thermostability of HEX A was decreased. No immunological cross reacting material was found for HEX A or B. The mechanism seems to be the production of abnormal, unstable beta subunits, which are still capable of combining with alpha subunits to form functional HEX A.
Acetylglucosaminidase↗
Molecular heterogeneity of rabbit heart phosphorylase kinase.
Phosphorylase kinase (ATP: phosphorylase-b phosphotransferase, EC 2.7.1.38) from rabbit heart, when submitted to electrophoresis on Pevikon, separates into two discrete peaks A and B. The two peaks have been analyzed using reelectrophoresis, chromatography on DEAE-cellulose, thermal stability, inactivation by EGTA (ethyleneglycol-bis(beta-aminoethyl ether)-N,N'-tetraacetic acid) and reaction with an anti-muscle phosphorylase kinase antiserum. It can be concluded that rabbit heart extracts contain two isozymes of phosphorylase kinase. The more negatively charged isozyme seems to be identical with the muscle enzyme. The other isozyme resembles the liver enzyme but differs from the major fraction of the latter by its charge. It is likely that there exist at least three molecular types of phosphorylase kinase.
Animals↗
Studies on the nature of different molecular forms of glucose-6-phosphate dehydrogenase purified from human leukocytes.
Several molecular forms of human glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NADP+ 1-oxidoreductase, EC 1.1.1.49) corresponding to different stages of post-synthetic modifications have been purified from human leukocytes. The various enzyme forms were different in their specific activity, their kinetic properties and their isoelectrofusing pattern. The molecular weight of the subunits of the different forms was not modified. The changes in the electrofocusing pattern were not due to modifications of the N-terminal ends, the oxidation of thiol groups or the non-covalent fixation of an acid molecule upon the enzyme. Carboxypeptidase B cleaved a C-terminal lysine from the different enzyme forms and shifted the isoelectric point of the different enzyme active bands towards the acid pH. The different enzyme forms studied here seemed to result from the action upon 'native glucose-6-phosphate dehydrogenase' of 'modifying factors' especially abundant in some leukemic granulocytes. The modifying factors did not seem to be consumed during the 'modification' of glucose-6-phosphate dehydrogenase. Moreover, the storage for one year of unmodified enzyme resulted in changes in its electrofocusing pattern similar to those quickly induced by the 'modifying factors'. Consequently it appears that the modifying factors are catalysts of the modification of special residues of glucose-6-phosphate dehydrogenase. The hypothesis that this modification involves the deamination of asparagine or glutamine residues is put forward.
Amino Acid Sequence↗
Electrophoretic modifications of three enzymes in extracts of human and bovine lens. Posttranslational "aging" of lens enzymes.
Electrophoretic modifications have been found in extracts from human and bovine lenses for three enzymes: glucose-6-phosphate dehydrogenase, triosephosphate isomerase and nucleoside phosphorylase. Increased anodic mobility is observed in all cases. It is more pronounced than in red cell lysates, also more evident in lenses from adult than from young animals. These results give evidence of posttranslational "aging" of enzyme molecules in lenses.
Aging↗
Gene dosage effect in human triploid fibroblasts.
The activity of 13 cytoplasmic enzymes has been determined in fibroblast extracts from 9 triploid and 13 control lines. The results show a high activity for 2 X-linked enzymes, glucose 6-phosphate dehydrogenase and phosphoglycerate kinase. These data, together with cytogenetic observations, support the contention that 2 X chromosomes were active in the triploid lines.
Fibroblasts↗
Isoenzyme pattern of phosphorylase in white blood cells and fibroblasts from patients with liver phosphorylase deficiency.
Isoenzyme patterns of phosphorylase in white blood cells and cultured fibroblasts of a patient affected with liver-type phosphorylase deficiency were studied. Three bands were observed with electrofocusing of white blood cells and liver from controls. In the white blood cells of the patient only two bands were observed. Patient and control fibroblasts showed two bands, probably identical to the two bands observed in the patient's white blood cells. These results indicate that the liver-type phosphorylase is not expressed in the cultured fibroblasts.
Brain↗
Modifications of purified glucose-6-phosphate dehydrogenase and other enzymes by a factor of low molecular weight abundant in some leukemic cells.
Highly purified platelet glucose-6-phosphate dehydrogenase (G6PD; D-glucose-6-phosphate:NADP+ 1-oxidoreductase, EC 1.1.1.49) can be modified in its isoelectric point and its molecular specific activity by extracts of some leukemic granulocytes. The "G6PD modifying factors" are relatively small molecules (molecular weight slightly under 5000), thermostable, dialyzable, and ultrafilterable. These molecules are destroyed by various endo- and exopeptidases and by serine enzymes present in crude extracts of leukocytes and commercial preparations of ribonuclease. The alterations of platelet G6PD due to the "G6PD modifying factors" are stable and not reversible by dialysis or further chromatography. The leukemic extracts which are able to modify G6PD also can modify the electrophoretic mobility and (or) the enzymatic activity of purified leukocyte pyruvate kinase, 6-phosphogluconate dehydrogenase, and glucosephosphate isomerase. The chemical nature of such modifications and their relationships with post-translational modifications which occur in leukemic or normal cells are discussed.
Blood Platelets↗
Prenatal diagnosis of fucosidosis.
A pregnancy from a family at risk for fucosidosis was monitored. Determinations of fucosidase and mannosidase were performed on the serum and white blood cells of several members of the family, om amniotic fluid and amniotic fluid cells of the fetus at several passages, and on fibroblast cell lines from index cases. The fetus was diagnosed as being free from the disease. This conclusion was confirmed after birth by fucosidase determination in plasma and white cells from cord blood, and in the placenta. Fluctuations in fucosidase activity were observed in extracts from cultured amniotic cells at various passages. The possible causes of this variability are discussed.
Adult↗
Aging and accuracy of protein synthesis in man: search for inactive enzymatic cross-reacting material in granulocytes of aged people.
Enzyme activities and immunological reactivities of seven different enzymes have been assayed in the polymorphonuclear leukocytes from 10 newborns, 10 aged (over 80 years old) and 10 young adults (20-30 years old). Polymorphonuclears have been chosen because both in the newborns, and in the aged people, they are young cells whose life span is a few hours only. Five cytoplasmic enzymes have been immunologically studied by means of monospecific antienzyme sera: leukocyte pyruvate kinase by immunoinactivation, glucose-6-phosphate dehydrogenase and glucose phosphate-isomerase by electroimmunodiffusion, lactic dehydrogenase (muscle-type) by radial immunodiffusion. Two lysosomal enzymes (alpha-mannosidase and beta-glycuronidase) have been titrated immunologically with the same polyvalent antihuman leukocyte rabbit serum. Small but significant differences in activity were observed for several of the enzymes. By contrast, no significant difference was found, for any of the seven enzymes, as regards the ratio enzyme activity/immunological reactivity, between newborns, young adults and aged people. These results of not support the theory that a decreased accuracy of the protein synthesis machinery is responsible for aging and death. By contrast, the authors emphasize that the enzyme abnormalities reported by various authors in old animals or in old fibroblast cultures closely resemble those demonstrated to be "post-translational modifications" in the case of human glucose-6-phosphate dehydrogenase.
Adult↗
Hexosaminidase C in Tay-Sachs and Sandhoff disease.
1. Hexosaminidase C has been purified from human placenta. Complete separation from hexosaminidases A and B was achieved. 2. The following properties of hexosaminidase C differ from those of the A and B isozymes. Presence in the supernatant rather than the lysosomes, neutral pH optimum, higher molecular weight, lack of activity on beta-N-acetylgalactosamine derivatives, and lack of immunological relationship. 3. Hexosaminidase C is active in patients deficient in hexosaminidases A and B and can be recognized by its characteristic electrophoretic mobility. It is concluded that the genetic origin of hexosaminidase C is probably different from that of hexosaminidases A and B.
Acetylgalactosamine↗
Absence of hexosaminidase A and B in a normal adult.
In the course of screening for heterozygotes for beta-hexosaminidase deficiency, the serum and white cells of a clinically normal father of deficient children were found to have an apparent deficiency for both hexosaminidases A and B, assayed with an artificial substrate, 4-methylumbelliferyl-beta-glucosaminide. No inhibitor was present. Assayed with a natural substrate, n-acetylgalactosaminyl beta 1-4 galactosyl beta 1-4 glucosyl ceramide, which had been isolated from the brain of a patient with Tay--Sachs disease and labeled in the terminal n-acetyl-galactosamine, a value in the heterozygote range was found. It was concluded that the proband is probably a double heterozygote for two mutations; one is the classic Sandhoff type (lack of hexosaminidases A and B), giving rise to deficient offspring when combined with the same mutation borne by the wife. The other obscures any activity with the artificial substrate but allows an action on natural substrates, explaining the normal life of its carrier.
Aminoglycosides↗
[Fructose 1,6-diphosphatase deficiency in 2 sisters].
The discovery of a fructose-1,6-diphosphatase deficiency in two sisters leads to the discussion of the various loading tests which are required for the diagnosis. The diagnosis may be discussed clinically with type I glycogenosis, and biologically with hereditary fructose intolerance. The specific characteristics of these disorders are analyzed as well as the problem of fructose induced hypoglucosemia. The failure of the treatment with folic acid in one of the cases leads to emphasize the suppression of prolonged fast in order to avoid acute accidents.
Carbohydrate Metabolism, Inborn Errors↗
[Enzyme deficiencies detected on cultured fibroblasts and amniotic cells. Application to prenatal diagnosis].
The detection of enzumatic deficiencies on cultured cells is reviewed from the literature and the authors personal experience. The application to the antenatal diagnosis of enzymatic genetic diseases is discussed, with special reference to lysosomal enzymes, of which the deficiency is most frequent. The authors insist on the importance of such detections and the problems which they may have to meet.
Amniotic Fluid↗
The isozymes of glycogen phosphorylase in human and rabbit tissues. II. Electrofocusing in polyacrylamide gels.
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Animals↗