title: Contribution of proteolytic and metabolic sources to hepatic glutamine by (2)H NMR analysis of urinary phenylacetylglutamine (2)H-enrichment from (2)H(2)O.
abstract: Proteolytic and cataplerotic sources of hepatic glutamine were determined by (2)H NMR analysis of urinary phenylacetylglutamine (PAGN) (2)H-enrichments in eight healthy subjects after (2)H(2)O and phenylbutyric acid ingestion. Body water enrichment was 0.49+/-0.03%. PAGN was enriched to lower levels with significant differences between the various glutamine positions. PAGN position 2 enrichment=0.33+/-0.02%; 3R=0.27+/-0.02%; 3S=0.27+/-0.02% and position 4=0.17+/-0.01%. Position 3R,S enrichments are conditional with the net conversion of citrate to glutamate and are therefore markers of cataplerosis. From the ratio of positions 3R,S to body water enrichment, 55+/-3% of hepatic glutamine was derived from cataplerosis and 45+/-3% from proteolysis. In conclusion, enrichment of PAGN 3R,S hydrogens relative to that of body water reflects the contribution of cataplerotic and proteolytic sources to hepatic glutamine.
authors.affiliation: NMR Research Unit, Department of Biochemistry and Center for Neurosciences and Cell Biology, Faculty of Sciences and Technology, University of Coimbra, 3001-401 Coimbra, Portugal.
authors.forename: Cristina
authors.initials: C
authors.lastname: Barosa
authors.forename: Manuela
authors.initials: M
authors.lastname: Almeida
authors.forename: M Madalena
authors.initials: MM
authors.lastname: Caldeira
authors.forename: Filipe
authors.initials: F
authors.lastname: Gomes
authors.forename: John G
authors.initials: JG
authors.lastname: Jones
mesh_terms: D019343:Citric Acid / Q000378:metabolism*; D005973:Glutamine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism*; D006801:Humans; D008099:Liver / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D010654:Phenylbutyrates / Q000652:urine*
chemical_list: D010654:Phenylbutyrates; D005973:Glutamine; D019343:Citric Acid; C003089:phenylacetylglutamine