Further characterization of a heat-stable alkaline phosphatase with low sensitivity to L-phenylalanine.
A heat-stable alkaline phosphatase, hitherto found in two families with inherited hyperphosphatasemia, was further characterized. The enzyme was similar to serum placental alkaline phosphatase from pregnant women concerning its apparent affinity constant (Km) for 4-nitrophenyl phosphate and its reactivity with H7 monoclonal anti-placental alkaline phosphatase (PLAP) antibodies, but different in the following respects: it exhibited greater heat stability, a higher pH optimum, lower sensitivity to inhibition by L-phenylalanine, and no reactivity with C2 monoclonal anti-PLAP antibodies. The low sensitivity to L-phenylalanine suggests that the enzyme might correspond to a rare phenotype of placental alkaline phosphatase found in human term placenta.
Onica
D
D
Department of Clinical Chemistry, Karolinska Institutet, Södersjukhuset Stockholm, Sweden.
Rosendahl
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K
Waldenlind
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L
D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000911:Antibodies, Monoclonal; D004587:Electrophoresis, Agar Gel; D004795:Enzyme Stability; D005260:Female; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007124:Immunoenzyme Techniques; D007525:Isoelectric Focusing; D008875:Middle Aged; D010649:Phenylalanine / Q000494:pharmacology*; D010920:Placenta / Q000201:enzymology; D011247:Pregnancy
D000911:Antibodies, Monoclonal; D010649:Phenylalanine; D000469:Alkaline Phosphatase