Quantitative method for determining serum alkaline phosphatase isoenzyme activity: estimation of intestinal component.
Intestinal alkaline phosphatase activity was measured using levamisole inhibition, and results were compared with a previously reported method using L-phenylalanine. Sixty two per cent intestinal, 39% placental, and 1.3% of either bone or liver alkaline phosphatase activity remained when alkaline phosphatase activity was inhibited in a 2-amino-2-methyl-1-propanol (AMP) buffer reagent system with 10 mmol/l levamisole (final assay concentration 8.1 mmol/l). The assay imprecision (SD) was 0.6 U/l compared with 3.9 U/l using L-phenylalanine for specimens with total alkaline phosphatase activity less than 250 U/l (reference range 30-120 U/l). In serum pools with raised total alkaline phosphatase activity errors in recovered intestinal activity were small (usually less than 3 U/l) when intestinal alkaline phosphatase was added. Much larger errors and many underestimated results were found using L-phenylalanine. For non-haemolysed specimens it is concluded that an assay based on levamisole inhibition provides a better measure of intestinal alkaline phosphatase activity than L-phenylalanine.
Peake
M J
MJ
Department of Biochemistry and Chemical Pathology, Flinders Medical Centre, Bedford Park, South Australia.
Pejakovic
M
M
White
G H
GH
D000469:Alkaline Phosphatase / Q000037:antagonists & inhibitors / Q000097:blood*; D001842:Bone and Bones / Q000201:enzymology; D006461:Hemolysis; D006801:Humans; D007422:Intestines / Q000201:enzymology*; D007527:Isoenzymes / Q000097:blood*; D007978:Levamisole / Q000494:pharmacology; D008099:Liver / Q000201:enzymology; D008722:Methods; D010649:Phenylalanine / Q000494:pharmacology; D013773:Tetramisole / Q000031:analogs & derivatives / Q000494:pharmacology
D007527:Isoenzymes; D007978:Levamisole; D010649:Phenylalanine; C006226:4-bromotetramisole; D013773:Tetramisole; D000469:Alkaline Phosphatase