Substrate specificity of alkaline phosphatase from human polymorphonuclear leukocytes

Hypophosphatasia is an inherited disease in which a deficiency of the bone/liver/kidney or tissue nonspecific isoenzyme of alkaline phosphatase (AP; EC 3.1.3.1) occurs. All forms of the disease are characterized clinically by defective mineralization. Several biochemical abnormalities are associated with the deficiency of AP activity, e.g., increased urinary excretion of inorganic pyrophosphate (PPi) and phosphoethanolamine (PEA). Measurement of these analytes in kindreds of patients with hypophosphatasia may be useful in identifying carriers, and in understanding the inheritance of the disease. We studied biochemically 22 members of the kindred of a 24-year-old woman with hypophosphatasia. We measured activity of AP in serum and leukocytes, and the urinary excretion of PPi and PEA. Within this kindred, urinary excretion of PPi appeared to indicate carrier status, and among the clinically normal adults, values for this analyte were inversely correlated with the activity of AP in serum. These results suggest that urinary excretion of PPi is sensitive to subtle changes in the activity of AP.

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Hypophosphatasia and the Extracellular Metabolism of Inorganic Pyrophosphate: Clinical and Laboratory Aspects: Part I

Caswell¹,

Whyte²,

Russell³

1991

Critical Reviews in Clinical Laboratory Sciences

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Hypophosphatasia is a rare inherited disorder in which the activity of the bone/liver/kidney or tissue nonspecific form of alkaline phosphatase (ALP) is reduced. The clinical expression of the disease is highly variable, but in early life the severity tends to reflect the age of onset. Accordingly, the disease is often classified into perinatal, infantile, and childhood forms. Hypophosphatasia also occurs in adults. Some exhibit symptoms in adulthood for the first time, but others have a history of the disease in early life with an intervening symptom-free period. Defective mineralization of bones and teeth is the predominant clinical feature of all forms of the disease. Biochemically, the reduction in ALP activity is associated with alterations in the extracellular metabolism of various phosphorylated compounds, including inorganic pyrophosphate (PPi), phosphoethanolamine, and pyridoxal 5'-phosphate. Of these, PPi may have an especially important role in the development of the mineralization defect. Accordingly, the extracellular metabolism of PPi and its possible role in the regulation of mineralization will be discussed.

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Substrate specificity of alkaline phosphatase from human polymorphonuclear leukocytes

Cited by 4 publications

References 30 publications

Neutrophil alkaline phosphatase (NAP) score in the diagnosis of hypophosphatasia

Neutrophil alkaline phosphatase (NAP) score in the diagnosis of hypophosphatasia

Hypophosphatasia: biochemical screening of a Dutch kindred and evidence that urinary excretion of inorganic pyrophosphate is a marker for the disease.

Hypophosphatasia and the Extracellular Metabolism of Inorganic Pyrophosphate: Clinical and Laboratory Aspects: Part I

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