Effects of the addition of sulphur compounds to the diet on utilisation of protein in young growing rats

Abstract

A number of sulphur-containing compounds were added to a 10% casein diet in order to indicate their ability to replace a supplement of methionine. Net protein utilisation (NPU) was determined. Cysteine, homocysteine and methionine hydroxy analogue produced as great an increase in NPU as did methionine. Methionine sulphoxide increased the NPU to a lesser extent. Methionine sulphoximine, methyl methionine sulphonium hydrogen sulphate and methionine sulphone caused reductions in NPU. Other organic and all inorganic sulphur compounds showed no methionine sparing action. IntroductionDiets in many parts of the world are poor in protein quality and quantity. The limiting amino acid of such diets is most frequently methioninel and it could be argued that there is a world shortage of dietary sulphur amino acids. Synthetic amino acids are rarely added to human foods although there is a large-scale industry producing them for animal feeds. Methionine itself is relatively expensive and a