Argininosuccinate synthetase activity in cultured human lymphocytes

Oksana Lockridge, Elaine B. Spector, Arthur D. Bloom

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The activity of argininosuccinate synthetase (E.C. 6.3.4.5), a urea cycle enzyme, was measured in cultured human lymphocytes using a new radioactive assay. Control cells had a maximum specific activity of 15.7±8.7 nmoles per hour per milligram of protein and an apparent Km for citrulline of 2 × 10-4m, whereas cells derived from a patient with citrullinemia had no detectable activity. A nutritional variant, selected out of the citrullinemic lymphocyte population by ability to grow in citrulline, had a maximum specific activity of 10.7±3.8 nmoles/hr/mg and an apparent Km for citrulline of 2 × 10-2m. These measurements confirm the observation that citrullinemia is associated with a defect in argininosuccinate synthetase activity and provide further evidence that citrullinemia is expressed in cultured lymphocytes. The emergence of a nutritional variant with a partial defect in argininosuccinate synthetase enzyme suggests that this citrullinemic patient has a heterogeneous population of cells, some totally defective and others only partially defective in argininosuccinate synthetase. The new activity assay is described in detail.

Original languageEnglish (US)
Pages (from-to)395-407
Number of pages13
JournalBiochemical Genetics
Volume15
Issue number3-4
DOIs
StatePublished - Apr 1977

Fingerprint

Argininosuccinate Synthase
Citrullinemia
Lymphocytes
ligases
citrulline
Citrulline
defect
lymphocytes
assay
enzyme
urea
Assays
urea cycle enzymes
Defects
protein
assays
cells
Enzymes
Population
Urea

Keywords

  • argininosuccinate synthetase
  • citrullinemia
  • human lymphocyte lines
  • urea cycle

ASJC Scopus subject areas

  • Biochemistry
  • Genetics

Cite this

Argininosuccinate synthetase activity in cultured human lymphocytes. / Lockridge, Oksana; Spector, Elaine B.; Bloom, Arthur D.

In: Biochemical Genetics, Vol. 15, No. 3-4, 04.1977, p. 395-407.

Research output: Contribution to journalArticle

Lockridge, Oksana ; Spector, Elaine B. ; Bloom, Arthur D. / Argininosuccinate synthetase activity in cultured human lymphocytes. In: Biochemical Genetics. 1977 ; Vol. 15, No. 3-4. pp. 395-407.
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