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Oxidation of galactose by galactose‐1‐phosphate uridyltransferase‐deficient lymphoblasts
Author(s) -
Yager C.,
Gibson J.,
States B.,
Elsas L. J.,
Segal S.
Publication year - 2001
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 - 10.1023/a:1010529629750
Subject(s) - galactose , lymphoblast , galactosemia , enzyme , sugar phosphates , sugar , mutation , cell culture , genotype , biochemistry , biology , chemistry , medicine , endocrinology , gene , genetics
The ability of EB virus‐transformed lymphoblasts with undetectable galactose‐1‐phosphate uridyltransferase (GALT) from 15 galactosaemic patients to oxidize [1‐ 14 C]galactose to 14 CO 2 was compared to that of cells from 7 normal subjects. The oxidation of galactose but not of glucose was markedly diminished by cells from Q188R homozygous galactosaemic patients but was not absent. After 2.5 h these cells liberated 14 CO 2 at nearly 3% and at 5 h up to 9% of normal. Cells from patients homozygous for the S135L mutation produced much larger amounts of 14 CO 2 (15–17% of normal) and were distinguishable from the Q188R homozygous cells. A cell line with a homozygous deletion of the GALT gene oxidized galactose at 7% of the normal rate, suggesting that pathways(s) other than GALT exist in these cells as well as Q188R homozygous cells for oxidation of galactose to CO 2 . Concentration dependence studies are consistent with the presence of a pathway that is unsaturable or has a very high K m . The ability of 10 7 lymphoblasts with the S135L genotype to oxidize more than 7% of the sugar to 14 CO 2 in 5 h suggests the presence of residual GALT despite the inability to detect the activity by enzymatic analysis.