The Activity of Galactose-1-phosphate Uridyltransferase and Galactokinase in Human Fetal Organs

Shin-Buehring, Y.S.; Beier, Thomas; Tan, Adelene Y; Osang, M.; Schaub, J.

doi:10.1203/00006450-197710000-00004

Cited by 39 publications

(25 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The ratio of galactokinase activity to that of transferase is about 0.5 in the ovary. It is much lower in human erythrocytes and testes, but similar to that reported for liver and kidney (14). The fact that UDPGlc pyrophosphorylase has the highest sp act in the ovary suggests that nucleotide sugars production may be important in this tissue.…”

Section: Preparation Of Tissue Homogenate For Enzyme Studiesmentioning

confidence: 62%

Galactose Metabolism in Human Ovarian Tissue

Ng²,

Kaufman

et al. 1989

Pediatr Res

View full text Add to dashboard Cite

ABSTRACT. Galactose metabolism was studied in human ovarian tissue obtained from 14 women controls between 21 and 72 y of age, and one 21-y-old galactosemic patient with hypergonadotrophic hypogonadism. Tissue slices were incubated with l-'4C-galactose, and labeled intermediates were analyzed by anion-exchange column chromatography. Activities of enzymes related to the galactose pathway: galactokinase, transferase, epimerase, uridine diphosphoglucose (UDPGlc) and uridine diphosphogalactose pyrophosphorylases, and UDPGlc and uridine diphosphogalactose pyrophosphatases were measured in ovarian homogenates using radioisotopic, spectrophotometric, and fluorometric techniques. Incorporation of carbon label from l-'4C-galactose into various galactose and glycolytic intermediates, as well as carbon dioxide and TCA-insoluble materials was demonstrated in samples from non-galactosemic controls. In tissue from the galactosemic individual, no labeled carbon dioxide was produced and very little incorporation into TCA-insoluble material was found. Labeled galactose-1-phosphate was elevated. In normal ovarian tissue, specific activities of galactokinase, transferase, epimerase, and UDPGlc pyrophosphorylase are much higher than those found in the red cells and in testes. UDPGlc pyrophosphorylase activity is about 50 times that of transferase, suggesting that uridine nucleotide sugars have an important role in the normal development and function of the ovary. It is hypothesized that premature ovarian failure. often observed in ~a t i e n t s with galactosemia, is due to interference with nucleotide sugar metabolism and the synthesis of galactose containing glycoproteins and glycolipids consequent to the enzymatic defect in the major pathway of galactose metabolism. (Pediatr Res 25:151-155,1989) Abbreviations transferase, galactose-1-phosphate uridyl transferase epimerase, uridine diphosphogalactose-4-epimerase G6PD, glucose-6-phosphate dehydrogenase PGM, phosphoglucomutase TCA, trichloroacetic acid UDPGlc, uridine diphosphoglucose UDPGal, uridine diphosphogalactose UTP, uridine triphosphate treatment is begun in early infancy (1). The clinical symptoms of gonadal insufficiency have included partial or complete failure of secondary sexual development, primary amenorrhea, the postpubertal occurrence of oligomenorrhea, and secondary amenorrhea. Although streak ovaries have been observed in two patients (2, 3), the pathophysiology of the ovarian insult is unknown. It has been hypothesized that metabolites of galactose, particularly galactose-I-phosphate, may be toxic to the ovarian parenchyma during the prenatal state (4) or the perinatal period (1). The exact mechanism of this toxicity, however, has not been elucidated.To gain a better understanding of galactose metabolism in the normal human ovary, galactose oxidation and its by-products were studied in ovarian tissue slices. In addition, the enzymes involved in the metabolic process were assayed, including galactokinase, galactose-1 -phosphate uridyl transferase, UDPGal-4-ep...

show abstract

Section: Preparation Of Tissue Homogenate For Enzyme Studiesmentioning

confidence: 62%

Galactose Metabolism in Human Ovarian Tissue

Ng²,

Kaufman

et al. 1989

Pediatr Res

View full text Add to dashboard Cite

show abstract

“…Fetal human brain and adult rat brain, among many tissues tested, were shown to have the lowest specific activities of the three cytoplasmic enzymes necessary for the conversion of galactose to glucose (2,5,7,26). The rate-limiting enzyme in brain seems to be uridyl-transferase (17).…”

Section: Discussionmentioning

confidence: 99%

“…Compared to liver, brain activity in the adult rat amounted to 27% for galactokinase (7), 15% for transferase (2), and 52% for epimerase (5). Shin-Buehring et al (26) reported that activity for the first two enzymes in the brain of human fetuses stayed at a low and fairly constant level between the 7th and 28th wk of gestation. Despite the presence of these enzymes, the mammalian brain is not dependent on preformed galactose for the synthesis of galactolipids, gangliosides, mucopolysaccharides, and glycoproteins, because the necessary UDPgalactose can be formed from UDPglucose catalyzed by the epimerase.…”

mentioning

confidence: 99%

Utilization of Galactose in Cultured Brain Cells of Neonatal Mice

et al. 1985

View full text Add to dashboard Cite

“…Bertoli and Segal (1966) and Cohn and Segal (1969) reported that frozen rat tissues showed no loss of uridyl transferase and UDPglucose 4-epimerase activities, respectively, during storage at -45°C for periods of up to 1 month. According to Shin-Buehring et al (1977), human galactokinase is less stable than uridyl transferase in frozen supernatants of tissue homogenates when stored at -20°C. We therefore compared the galactokinase activities of rat liver which had been stored at -60° for 1 year, and of tarnmar wallaby liver similarly stored for 3 months, with those of fresh tissues; no significant differences between frozen and fresh tissues were found.…”

Section: Hexose-i-phosphate Uridylyl Transferasementioning

confidence: 99%

Enzymes of Galactose Metabolism in Livers of Suckling and Adult Tammar Wallabies (Macro Pus Eugenii) and Other Marsupials

Vernon¹,

Messer²,

Green³

1981

Aust. Jnl. Of Bio. Sci.

View full text Add to dashboard Cite

The activities of galactokinase, hexose-I-phosphate uridylyl transferase and UDPglucose 4-epimerase in homogenates of livers of two adult and 20 suckling tammar wallabies aged from 6 to 50 weeks were investigated. The activities of all three enzymes were high until 24-30 weeks post partum, after which they declined to low levels.The activities of the three liver enzymes were high in pouch young of six other species of marsupial.Comparison of the activities of the three liver enzymes in suckling tammar wallabies with those in suckling rats showed no difference between the two species in regard to galactokinase and uridylyl transferase, but the UDPglucose 4-epimerase activity in tammar wallabies was approximately double that found in rats. This may be related to the high galactose content of tammar wallaby milk compared with rat milk.In suckling tammar wallabies, the liver had higher enzyme activities than other tissues studied.It is concluded that, contrary to the suggestion of Stephens et al. (1975), pouch young marsupials are not deficient in their ability to metabolize galactose.

show abstract

The Activity of Galactose-1-phosphate Uridyltransferase and Galactokinase in Human Fetal Organs

Cited by 39 publications

References 7 publications

Galactose Metabolism in Human Ovarian Tissue

Galactose Metabolism in Human Ovarian Tissue

Utilization of Galactose in Cultured Brain Cells of Neonatal Mice

Enzymes of Galactose Metabolism in Livers of Suckling and Adult Tammar Wallabies (Macro Pus Eugenii) and Other Marsupials

Contact Info

Product

Resources

About