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Biochemical studies of a human low‐activity galactose‐1‐phosphate uridyl transferase variant
Author(s) -
Ng W. G.,
Kline F.,
Lin J.,
Koch R.,
Donnell G. N.
Publication year - 1978
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1007/bf01805583
Subject(s) - galactosemia , transferase , enzyme , biochemistry , chemistry , galactose , histidine , galactitol , enzyme assay
A low activity galactose‐1‐phosphate uridyl transferase (transferase) variant in a newborn infant has been demonstrated by biochemical studies in erythrocytes and cultured skin fibroblasts. The newborn infant was a galactosaemic suspect identified in a neonatal metabolic screening programme. On breast feeding, he did well without clinical symptoms of galactosaemia during the first 15 days of life. However, substantial amounts of erythrocyte galactose‐1‐phosphate and urinary galactitol corresponding to the levels in untreated galactosaemic patients, along with mild amino aciduria, were found. The transferase activity, as measured by a sensitive micro kinetic radioisotopic method, was about 7–10% of the normal. On starch gel electrophoresis, the enzyme from the haemolysate had similar mobility as the normal in Tris‐glycine buffer, pH 8.8 and phosphate buffer, pH 7.0, but had a slower mobility than that of the normal in the histidine buffer, pH 7.8. The mobility difference was much clearer in a semipurified enzyme preparation. The transferase enzyme in the haemolysate appeared to be more heat labile.