Abstract
A patient suffering from a progressive neurological disorder with severe mental retardation excreated increased amounts of carnosine (β-alanyl-histidine) in urine. A strongly decreased activity of carnosinase was found in the serum of this patient, who is the first child of healthy consanguineous parents. Two patients with identicla abnormalities have been described by Perry et al. [1]. In order to detect other patients with such a, presumably genetically determined, deficiency of serum carnosinase activity, a new method has been developed for the determination of the enzymic activity using L-carnosine-(β-alabyl-1-11C) as a substrate. The serum carnosinase activity was calculated from the ratio disintegrations per minute β-alanine: total disintegrations per minute. The carnosinase activity had been detemined in the serum of newborns, older children, and adults. During the first 10 years of life a striking correlation was established between the measured serum carnosinase activity and the age of the human subject. Newborns possess only very low activities (maximally 0.1 unit/liter during the first 50 days of life whereas children above the age of 10 years have activities between 20 and 70 units/liter,a range found for the enzymic activities in serum of 40 adults, varying in age between 20 and 11 years. This relationship bewteen age of the subjects and the measured enzymic activities has to be considered in view of detection of more patients with the described dipeptiduria, which probably can be classified as a no-threshold type.
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Trembles, J., van Heeswijk, P., van Munster, P. et al. 3. Carnosinase deficiency related to development of carnosinase activity. Pediatr Res 5, 83 (1971). https://doi.org/10.1203/00006450-197102000-00008
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DOI: https://doi.org/10.1203/00006450-197102000-00008