Determination of bioavailability of some long-chain N-substituted derivatives of L-methionine and L-lysine.
The bioavailability of N-acyl-L-methionine derivatives has been determined using microbiological assay with Tetrahymena pyriformis. It was found that palmitoyl- and stearoyl-L-methionine, stearoyl-L-methionine ethyl ester, and stearoyl-L-methionine sodium salt were partially utilized (14-38%) for growth of the microorganism. These compounds partially inhibited utilization of free methionine added to the media. The shorter derivatives, acetyl-, hexanoyl-, lauroyl-, and myristoyl-L-methionine completely inhibited the growth of T. pyriformis. This effect was not reversed when DL-methionine was added to the media. N6-fatty acyl L-lysine derivatives gave low availability values (3-18%) in microbiological assessment with T. pyriformis. N2-Acetyl-and N6-acetyl-lysine did not inhibit the utilization of the added parent amino acid. Nutritional evaluation of L-methionine derivatives by the rat growth method using net protein ratio (NPR) as the performance index indicated complete availability of stearoyl-L-methionine, stearoyl-L-methionine sodium salt, and partial availability of stearoyl-L-methionine ethyl ester (52%), stearoyl-L-methionylglycine (32%), and lauroyl-L-methionine (75%).
D000818:Animals; D001681:Biological Assay; D001682:Biological Availability; D001835:Body Weight / Q000187:drug effects*; D004044:Dietary Proteins / Q000494:pharmacology*; D008239:Lysine / Q000031:analogs & derivatives* / Q000378:metabolism; D008715:Methionine / Q000031:analogs & derivatives* / Q000378:metabolism; D009753:Nutritive Value; D051381:Rats; D013769:Tetrahymena pyriformis / Q000187:drug effects*
D004044:Dietary Proteins; D008715:Methionine; D008239:Lysine