Hypoxanthine-guanine phosphoribosyltransferase: characteristics of the mutant enzyme in erythrocytes from patients with the Lesch-Nyhan syndrome.
نویسندگان
چکیده
The Lesch-Nyhan syndrome is characterized clinically by choreoathetosis, spasticity, selfmutilation, and mental and growth retardation. Biochemically, there is a striking reduction of hypoxanthine-guanine phosphoribosyltransferase (HGPRT) activity in affected individuals. We have examined erythrocytes from 14 patients with the Lesch-Nyhan syndrome for the presence of hypoxanthine-guanine phosphoribosyltransferase activity and enzyme protein. In contrast to the usual finding of no detectable hypoxanthine-guanine phosphoribosyltransferase activity, we have found low levels (0.002-0.79 nmoles/mg protein per hr) of hypoxanthine-guanine phosphoribosyltransferase activity in erythrocyte lysates from five of these patients. In three of the five patients, hypoxanthine-guanine phosphoribosyltransferase activity appeared to be substantially more labile in vivo than normal using erythrocytes which had been separated according to their density (age). Immunochemical studies using a monospecific antiserum prepared from a homogeneous preparation of normal human erythrocyte hypoxanthine-guanine phosphoribosyltransferase revealed immunoreactive protein (CRM) in hemolysate from all 14 patients with the Lesch-Nyhan syndrome. The immunoreactive protein from each patient gave a reaction of complete identity with normal erythrocyte hypoxanthine-guanine phosphoribosyltransferase and was present in quantities equal to those observed in normal erythrocytes. In addition, a constant amount of CRM was found in erythrocytes of increasing density (age) from patients with the Lesch-Nyhan syndrome despite the decreasing hypoxanthine-guanine phosphoribosyltransferase activity. These studies confirm previous data which indicate that the mutations leading to the Lesch-Nyhan syndrome are usually, if not always on the structural gene coding for hypoxanthine-guanine phosphoribosyltransferase. In addition, although the mutant proteins appear to be present in normal amounts, they are often very labile in vivo with respect to enzymatic activity. These observations suggest that therapy directed at stabilization or activation of enzyme activity in vivo may be of potential benefit.
منابع مشابه
Studies on hypoxanthine-guanine phosphoribosyltransferase in fibroblasts from patients with the Lesch-Nyhan syndrome. Evidence for genetic heterogeneity.
The Lesch-Nyhan syndrome has been characterized by an apparently complete deficiency in erythrocytes of an enzyme of purine metabolism, hypoxanthine-guanine phosphoribosyltransferase. Recent studies have suggested that low levels of this enzyme may be present in skin fibroblasts cultured from these patients. In the present study, we have confirmed the presence of hypoxanthine-guanine phosphorib...
متن کاملStudies on Hypoxanthine-Guanine Phosphor&or yltransferase in Fibroblasts from Patients with the Lesch-Nyhan Syndrome
The Lesch-Nyhan syndrome has been characterized by an apparently complete deficiency in erythrocytes of an enzyme of purine metabolism, hypoxanthine-guanine phosphoribosyltransferase. Recent studies have suggested that low levels of this enzyme may be present in skin fibroblasts cultured from these patients. In the present study, we have confirmed the presence of hypoxanthine-guanine phosphorib...
متن کاملDietary-induced variation of hypoxanthine-guanine phosphoribosyl transferase activity in patients with the Lesch-Nyhan syndrome.
We have studied three patients with the Lesch-Nyhan syndrome to assess the effect of dietary purines on erythrocyte hypoxanthine-guanine phosphoribosyltransferase (HGPRT) activity. During dietary purine restriction HGPRT activity rose in all three patients; resumption of normal dietary purine intake or the addition of adenine (10 mg/kg per day) to a purinefree diet resulted in a fall in HGPRT a...
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The mutation in a young gouty male with a partial deficiency of hypoxanthine-guanine phosphoribosyltransferase has been evaluated. The serum uric acid was 11.8 mg/100 ml, and the urinary uric acid excretion was 1,279 mg/24 h. Erythrocyte hypoxanthine-guanine phosphoribosyltransferase was 34.2 nmol/h/mg, adenine phosphoribosyltransferase was 36.5 nmol/h/mg and phosphoribosylpyrophosphate was 2.6...
متن کاملOverproduction of uric acid in hypoxanthine-guanine phosphoribosyltransferase deficiency. Contribution by impaired purine salvage.
The contribution of reduced purine salvage to the hyperuricemia associated with hypoxanthine-guanine phosphoribosyltransferase deficiency was measured by the intravenous administration of tracer doses of [8-(14)C]adenine to nine patients with normal enzyme activity, three patients with a partial deficiency of hypoxanthine-guanine phosphoribosyltransferase, and six patients with the Lesch-Nyhan ...
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ورودعنوان ژورنال:
- The Journal of clinical investigation
دوره 51 7 شماره
صفحات -
تاریخ انتشار 1972