Porphyrinuria in rats fed oxidized-casein: a preliminary communication

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Abstract
It is confirmed that casein treated with H2O2 contains no methionine detectable analytically or by growth expt''s.; partition chromatography of an acid hydrolysate revealed methionine sulphpne and cysteic acid but no other abnormal constituent reacting with ninhydrin. Rats fed a diet including such oxidized casein rapidly develop a porphyrinuria not preventable by supplements of methionine, tryptophan, histidine, lysine or glutamic acid alone or in combination. Satisfactory growth followed whenever methionine and tryptophan were both added, and the livers of such animals were invariably normal. Acute hepatic necrosis did not occur in rats fed oxidized casein supplemented only with tryptophan. The porphyrinuria could not be associated with any histologically detectable liver damage. Neither methionine sulphone nor cysteic acid added to a casein diet induced porphyrinuria. Chromatographic examination of the urine indicated that methionine sulphone is differently metabolized when present in peptide linkage than when fed as a supplement; such a peptide may be the porphy-rinurogenic agent.