Citrate and the conversion of carbohydrate into fat. A comparison of citrate and acetate incorporation into fatty acids.

culture medium. It is now realized that arylsulphatase can be produced in the absence of tyramine if a non-repressor sulphur compound is used as the sulphur source, and that the enzyme can also be formed with repressor sulphate sources if tyramine is included. Sulphur sources intermediate in the assimilation of sulphate to cysteine thus repress arylsulphatase synthesis whereas tyramine relieves the repression. The experiments on competitive metabolism with different sulphur sources in the presence and absence of tyramine suggest that the tyramine is an actual inducer and that it does not act by changing the sulphate assimilation pathway. Synthesis of arylsulphatase is produced by adding tyramine to cell suspensions and this synthesis is inhibited by chloramphenicol and puromycin without any lag (T. Harada, unpublished work). Tyramine, which is widely distributed in Nature, is a possible product of, arylsulphatase action and can be catabolized by micro-organisms. It is not clear why the induction effect is specific to tyramine since other aryl compounds, e.g. phydroxybenzoic acid, can be products of arylsulphatase action and can be dissimilated but do not act as inducers.