Ascertainment of <scp>D</scp>‐amino acids in germ‐free, gnotobiotic and normal laboratory rats

<jats:title>Abstract</jats:title><jats:p>Free <jats:sc>D</jats:sc>‐amino acids were ascertained in the blood serum, urine and aqueous ethanolic extracts of feces of germ‐free laboratory rats and a rat made gnotobiotic (tetra‐associated) with species of <jats:italic>Streptococcus, Lactobacillus</jats:italic> and <jats:italic>Clostridium</jats:italic>. <jats:sc>D</jats:sc>‐Amino acids were also determined in the brains of two germ‐free rats. For comparison, <jats:sc>D</jats:sc>‐amino acids were also measured in the blood serum of normal rats and the blood plasma, urine and feces of normal white mice. <jats:sc>D</jats:sc>‐Enantiomers of most protein <jats:sc>L</jats:sc>‐amino acids were detected in all physiological samples of animals. Quantities of free <jats:sc>D</jats:sc>‐amino acids were determined as <jats:italic>N(O)</jats:italic>‐pentafluoropropionyl‐(2)‐propyl esters by enantioselective gas chromatography and mass spectrometry. Stereoisomers of the bacterial marker 2,6‐diaminopimelic acid, analyzed as <jats:italic>N</jats:italic>‐trifluoroacetyl‐(2)‐propyl esters, were detected in feces of the gnotobiotic but not of the germ‐free rat. Copyright © 2001 John Wiley & Sons, Ltd.<jats:def-list> <jats:title>Abbreviations used:</jats:title> <jats:def-item> <jats:term>common protein amino acids are abbreviated according to three‐letter nomenclature</jats:term> <jats:def> <jats:p>Asx, Asp/Asn</jats:p> </jats:def> </jats:def-item> <jats:def-item> <jats:term>Glx</jats:term> <jats:def> <jats:p>Glu/Gln</jats:p> </jats:def> </jats:def-item> <jats:def-item> <jats:term>Dap</jats:term> <jats:def> <jats:p>2,6‐diaminopimelic acid</jats:p> </jats:def> </jats:def-item> <jats:def-item> <jats:term>GC‐SIM‐MS</jats:term> <jats:def> <jats:p>gas chromatographie/selected ion monitoring mass spectrometry</jats:p> </jats:def> </jats:def-item> <jats:def-item> <jats:term>Orn</jats:term> <jats:def> <jats:p>ornithin.</jats:p> </jats:def> </jats:def-item> </jats:def-list></jats:p>