The Utilization and Safety of Isomeric Sulfur-Containing Amino Acids in Mice

Abstract

Growth assays on a synthetic amino acid diet fed to mice showed that substituting D-methionine for the L-isomer resulted in a dose-dependent relative weight gain reaching approximately 76% when D-methionine was fed at a level equivalent to that optimal for the L-form. L-Cysteine and L-cystine stimulated growth in the presence of suboptimal levels of L-methionine, but D-cystine was growth depressing. L-Cystine is at least equally efficient in stimulating growth in the presence of D-methionine as in the presence of the L-isomer. Compared to a suboptimal (25% of maximum) level of L-methionine alone, supplements to this level L-methionine by N-acetyl-L-cysteine produced a weight gain of 214%; L-cysteine, 178%; L-cysteic acid, 154%; DL- + meso-lanthionine, 127%; L-cysteine sulfinic acid, 113%; D-cysteine, 76%; and S-methyl-L-cysteine, 13%. The observed growth-depressing effect of D-cysteine, D-cystine and S-methyl-L-cysteine at a concentration no greater than that optimal for methionine implies that these three sulfur-containing amino acids may be toxic. The results are discussed in terms of known and postulated transamination and transsulfuration pathways that govern the biological utilization of isomeric sulfur-containing amino acids and derivatives.

Origin, Microbiology, Nutrition, and Pharmacology of D‐Amino Acids

“…d-Cystine (d-Cys). Although l-Cys is not an essential amino acid for rodents, less l-Met is needed for growth if the diet contains l-Cys [153]. Our results also show that l-Cys is somewhat more efficient in sparing d-Met than in sparing l-Met in diets Fig.…”

“…d-Cysteine (d-CysSH). Although l-CysSH had a sparing effect of l-Met consumed by mice, d-CysSH did not [153]. In fact, d-CysSH imposed a metabolic burden as indicated by depressed growth when fed to mice with less than optimal levels of d-Met (Fig.…”

Nutritional and medicinal aspects of d-amino acids

“…Although L-cystine is not an essential amino acid for rodents, less L-Met is needed for growth if the diet contains L-cystine (Friedman and Gumbmann 1984b). Our results also show that L-cystine is somewhat more efficient in sparing D-Met than in sparing L-Met in diets containing low levels (0.29%) of the two isomers.…”

In Vitro Investigation of D- and Lenantiomer Synergistic Efects of Some Amino Acids

“…After oral administration of DCys, the concentration of sulfate in rat urine was shown to increase (about 55 % of the dose), but the concentration of taurine in the serum did not increase indicating that it is probably not or only slowly converted to taurine. The administration of L-Cys caused an increase the concentration of sulfate in the urine (about 33 % of the dose) as well as the concentration of taurine in the serum (KRIJGSHELD et al, 1981;FRIEDMAN and GUMBMANN, 1984). Other studies have showed that D-Cys has beneficial effects in acute alcohol intoxication and in cancer therapeutics and it shows no mutagenicity for humans (GLATT and OESCH, 1985;TSUKAMOTO et al, 1990;ROBERTS, 1995;OANCEA and FORMAGGIO, 2008).…”

“…Some animal experiments have demonstrated that D-methionine (Met) acts an otoprotective agent and its oral administration can be useful in mitigating hearing loss from platinum based chemotherapy, aminoglycosides and excessive noise (CAMPELL et al, 2007). On the other hand, other studies have showed that D-Met is poorly utilized in humans (EFRON et al, 1969;KIES et al, 1975;ZEZULKA and CALLOWAY, 1976;PRINTEN et al, 1979;FRIEDMAN and GUMBMANN, 1984).…”