Rapid liquid-chromatographic measurement of 3-methoxy-4-hydroxyphenylglycol and other monoamine metabolites in human cerebrospinal fluid.

The intestinally derived isoenzyme of alkaline phosphatase (ALP; EC 3.1.3.1) in serum is easily differentiated from other isoenzymes by electrophoresis on either starch, acrylamide, agar or agarose gels, or cellulose acetate membranes. In general, these techniques are not quantitative, but differential-inhibition techniques allow one to estimate the activity of the intestinal isoenzyme. LPhenylalanine preferentially inhibits intestinal (1) and placental (2) ALP; L-p-bromotetramisole inhibits the enzymes from bone.and liver, but has little effect on the intestinal or placental enzymes (3). The intestinal and placental isoenzymes can easily be differentiated, the latter being stable to heating at 65 for 60 mm (4). The amount of intestinal isoenzyme present customarily is expressed as a percentage of the total serum ALP activity, and for serum samples with above-normal ALP activity there appears to be a good correlation between detection of the intestinal enzyme after electrophoresis and the percentage of serum ALP activity inhibited with Lp-bromotetramisole (3). We have been interested in measuring L[IftLBoNA: