Cyclo (LL-dimethionine) is not utilized by rats as a methionine source

A low casein diet supplemented with 0.2-0.3% L-methionine promotes growth in rats, although it causes liver fat accumulation. Oligo-L-methionine on the other hand, prepared by papain-catalyzed oligomerization of L-methionine ethylester, stimulates growth in rats without causing liver fat accumulation, when added to a 8% casein diet. Oligo-L-methionine is a mixture of oligomers, with a oligomerization degree of 5 to 12, and is hydrolyzed very slowly by pancreatic juice and everted gut rings of rats. A methionine derivative, cyclo (LL-dimethionine), was examined in this study as it is hydrolyzed and/or absorbed very slowly from the intestinal tract and it was expected to be utilized as a methionine source without causing liver fat accumulation, when added to a low casein diet. It consists of two methionine residues linked together by two cis-peptide bonds and, therefore, is expected to be hydrolyzed and/or absorbed very slowly from intestinal tract. However, although cyclo (LL-dimethionine) was absorbed slowly from the intestinal tract, it was not utilized by rats as a methionine source, when added to 8% casein.