Accelerated purine biosynthesis de novo in skin fibroblasts deficient in hypoxanthine-guanine phosphoribosyltransferase activity

Rosenbloom, Frederick M.; Henderson, J. Frank; Kelley, William N.; Seegmiller, J. Edwin

doi:10.1016/0005-2787(68)90512-1

Cited by 57 publications

(64 citation statements)

References 6 publications

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“…(20,29). In previous studies in fibroblasts, results of this method have correlated well with in vivo determinations of rates of purine synthesis de novo (20,27,30). The generation and extraction of labeled FGAR and separation of FGAR from other labeled compounds were carried out as described (27,31).…”

Section: Methodsmentioning

confidence: 90%

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Variant human phosphoribosylpyrophosphate synthetase altered in regulatory and catalytic functions.

Becker¹,

Raivio²,

Bakay³

et al. 1980

J. Clin. Invest.

104

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A B S T R A C T An inherited, structurally abnormal and superactive form of the enzyme 5-phosphoribosyl 1-pyrophosphate (PP-ribose-P) synthetase (EC 2.7.6.1) has been characterized in fibroblasts cultured from a 14-yr-old male (S.M.) with clinical manifestations of uric acid overproduction present since infancy. PPribose-P synthetase from the cells of this child showed four-to fivefold greater than normal resistance to purine nucleotide (ADP and GDP) feedback inhibition ofenzyme activity and hyperbolic rather than sigmoidal inorganic phosphate (Pi) and by an accelerated, age-related decrement in enzyme activity in lysates of erythrocytes separated by specific density. Despite the diminished amount of PP-ribose-P synthetase in the S.M. erythrocyte population, S.M. erythrocytes had increased PPribose-P concentration and increased rates of incorporation of ['4C]adenine and hypoxanthine into acid-soluble nucleotides during incubation at 1 mM Pi. These findings provided further confirmation of the extent to which PP-ribose-P synthesis is modulated in the normal cell at physiological Pi concentration by purine nucleotide inhibition of PP-ribose-P synthetase.The activity and kinetic characteristics of PPribose-P synthetase from fibroblasts of the mother of patient S.M. indicated that this woman was a heterozygous carrier of the enzyme defect expressed in hemizygous manner by her son. INTRODUCTIONThe high-energy sugar phosphate 5-phosphoribosyl I-pyrophosphate (PP-ribose-P)' is an intermediate in the synthesis of purine, pyrimidine and pyridine nucleotides. The synthesis of PP-ribose-P from ATP and ribose-5-phosphate (Rib-5-P) is catalyzed by the enzyme PP-ribose-P synthetase (E.C. 2.7.6.1) in a reaction requiring Mg2+ and inorganic phosphate (Pi). Studies of PP-ribose-P production by intact cells (1, 2) and analyses of the kinetic characteristics of purified microbial (3-5) and mammalian (6-10) PP-ribose-P synthetases indicate that a substantial number of effector compounds including substrates, inhibitors, activators, and products influence enzyme activity.

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Section: Methodsmentioning

confidence: 90%

“…Tissue culture methods. Fibroblast cultures were initiated from skin biopsy specimens and were propagated as described (27). Strains were derived from: four normal male individuals; patient S.M.…”

mentioning

confidence: 99%

Variant human phosphoribosylpyrophosphate synthetase altered in regulatory and catalytic functions.

Becker¹,

Raivio²,

Bakay³

et al. 1980

J. Clin. Invest.

104

View full text Add to dashboard Cite

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“…An elevated intracellular concentration of PP-ribose-P has been demonstrated in erythrocytes [18,25] and in cultured fibroblasts [57] obtained from patients with both the "partial" and "complete" enzyme defect (Table V). Furthermore, the elevated concentration of PP-ribose-P in fibroblasts has been shown to be the result of decreased utilization of the compound rather than increased synthesis [57]. An increased concentration of PP-ribose-P could increase purine biosynthesis de novo by providing more substrate for the presumed limiting step of this pathway, PP-ribose-P amidotransferase.…”

Section: Pathogenesis Of Excessive Uric Acid Productionmentioning

confidence: 97%

“…The deficiency of this enzyme, which catalyzes the conversion of guanine to guanosine monophosphate (GMP) and hypoxanthine to IMP, might lead to an increase in purine synthesis de novo by virtue of a decreased synthesis of either IMP or GMP, inasmuch as these nucleotides are normally important inhibitors of purine biosynthesis de novo. Attempts to measure intracellular levels of GMP and IMP have been of only limited value, partly because of the very low intracellular concentration of these compounds under normal conditions [57]. An elevated intracellular concentration of PP-ribose-P has been demonstrated in erythrocytes [18,25] and in cultured fibroblasts [57] obtained from patients with both the "partial" and "complete" enzyme defect (Table V).…”

Section: Pathogenesis Of Excessive Uric Acid Productionmentioning

confidence: 99%

“…Attempts to measure intracellular levels of GMP and IMP have been of only limited value, partly because of the very low intracellular concentration of these compounds under normal conditions [57]. An elevated intracellular concentration of PP-ribose-P has been demonstrated in erythrocytes [18,25] and in cultured fibroblasts [57] obtained from patients with both the "partial" and "complete" enzyme defect (Table V). Furthermore, the elevated concentration of PP-ribose-P in fibroblasts has been shown to be the result of decreased utilization of the compound rather than increased synthesis [57].…”

Section: Pathogenesis Of Excessive Uric Acid Productionmentioning

confidence: 99%

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