The first step in the biosynthesis of porphyrins involves the condensation of glycine and succinyl coeneyme A to form b-aminolevulinic acid (ALA) (1, 2). The enzyme which catalyzes this reaction (ALA synthetase) is of particular interest, since it is an inducible enzyme in mammalian liver (3-6) subject to the "glucose effect" (5) and appears to be the rate-controlling enzyme in hepatic porphyrin biosynthesis (3, 5). Furthermore, a many-fold induction of the enzyme has recently been demonstrated in the liver of a patient with acute intermittent porphyria (7). The quantitative determination of ALA is of importance not only in the measurement of ALA synthetase activity but also in the diagnosis and management of several clinical disorders including acute intermittent porphyria (8-11) and lead intoxication (12).
A second aminoketone of physiological significance is aminoacetone (AA), which can be produced enzymically by the condensation of glycine and acetyl coenzyme A (13-16) or by the oxidation of threonine (15-21). Since both aminoketones occur in urine (9, 22) and both are produced in mitochondria (3,5,15,16,21), the measurement of these substances in both urine and tissues requires their separation. The method currently in wide use for urine allows for only the measurement of the total aminoketones since no separat,ion procedure is involved (9). The methods recently described for tissue supernatants (16, 23)) which have also been adapted for urine (24), involve the use of several chromatographic procedures and resins in order to separate ALA and AA. The present communication describes a modification of the method of Urata and Granick ( 16) that permits the separation of the aminoketones after conversion to pyrroles, by means of a single chromatographic procedure, which also concentrates these substances. This allows the determination of very small amounts of these materials. Recoveries are excellent even 53 MARVEX, THCHUDY, PERLROTH, COLLINS, AND HUNTER, JR.