Measurement of excitatory sulfur amino acids, cysteine sulfinic acid, cysteic acid, homocysteine sulfinic acid, and homocysteic acid in serum by stable isotope dilution gas chromatography-mass spectrometry and selected ion monitoring.
Oxidized sulfur-containing amino acids are recognized as agonists of excitatory amino acid receptors in the mammalian nervous system. Homologues of glutamic acid (homocysteine sulfinic acid and homocysteic acid) and aspartic acid (cysteine sulfinic acid and cysteic acid) have been shown to be agonistic to N-methyl-D-aspartate receptors in animal brain and have been demonstrated in brain tissue. Considerable evidence exists for the role of homocysteic acid and cysteine sulfinic acid as endogenous ligands for excitatory amino acid receptors. We report, for the first time, the quantitation of these compounds in normal human serum, by a newly developed gas chromatography-mass spectrometry method that employs stable isotope-dilution selected ion monitoring using internal standards prepared in our laboratory. We also report new methods of synthesis of stable isotope-labeled internal standards used in measuring cysteine sulfinic acid, cysteic acid, homocysteine sulfinic acid, and homocysteic acid.
Division of Hematology, University of Colorado Health Sciences Center, Denver 80262.
C R
CR
Santhosh-Kumar
J C
JC
Deutsch
J C
JC
Kolhouse
K L
KL
Hassell
J F
JF
Kolhouse
D001224:Aspartic Acid / Q000097:blood; D003544:Cysteic Acid / Q000097:blood*; D003545:Cysteine / Q000031:analogs & derivatives* / Q000097:blood; D003903:Deuterium; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006710:Homocysteine / Q000031:analogs & derivatives* / Q000097:blood; D006801:Humans; D007553:Isotope Labeling / Q000379:methods; D018377:Neurotransmitter Agents; D012016:Reference Values
D018377:Neurotransmitter Agents; D006710:Homocysteine; C007956:homocysteic acid; D001224:Aspartic Acid; C010982:homocysteinesulfinic acid; D003544:Cysteic Acid; D003903:Deuterium; D003545:Cysteine; C013461:cysteine sulfinic acid