Document Detail

Elevation of 2-methylcitric acid I and II levels in serum, urine, and cerebrospinal fluid of patients with cobalamin deficiency.
MedLine Citation:
PMID:  8345822     Owner:  NLM     Status:  MEDLINE    
Citrate synthase catalyzes the condensation of acetyl-coenzyme A (CoA) and oxaloacetic acid to form citric acid. The enzyme also catalyzes the condensation of propionyl-CoA and oxaloacetic acid with a maximal reaction velocity (Vmax) approximately 10(-4) times that of acetyl-CoA to form 2-methylcitric acid, which contains two asymmetric carbon atoms and exists as two pairs of related enantiomers designated as 2-methylcitric acid I and II. Cobalamin (Cbl) deficiency can lead to increases in intracellular levels of propionyl-CoA. To assess the magnitude of increased synthesis of 2-methylcitric acid in Cbl deficiency, we developed a new capillary gas chromatographic-mass spectrometric assay and measured 2-methylcitric acid levels in serum and cerebrospinal fluid (CSF) of normal subjects and patients with clinically confirmed Cbl deficiency. The normal range for 2-methylcitric acid level was 60 to 228 nmol/L for serum in 50 normal blood donors and 323 to 1,070 nmol/L for CSF in 19 normal subjects. In 50 patients with clinically confirmed Cbl deficiency, values for 2-methylcitric acid in serum ranged from 93 to 13,500 nmol/L; 44 (88%) had values above the normal range. In five patients with clinically confirmed Cbl deficiency, levels of the sum of 2-methylcitric acid I and II ranged from 1,370 to 16,300 nmol/L in CSF, and all five (100%) patients had levels above the normal range. We conclude that levels of 2-methylcitric acid are elevated in serum and CSF of most patients with Cbl deficiency.
R H Allen; S P Stabler; D G Savage; J Lindenbaum
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Metabolism: clinical and experimental     Volume:  42     ISSN:  0026-0495     ISO Abbreviation:  Metab. Clin. Exp.     Publication Date:  1993 Aug 
Date Detail:
Created Date:  1993-09-03     Completed Date:  1993-09-03     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0375267     Medline TA:  Metabolism     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  978-88     Citation Subset:  IM    
Department of Medicine, University of Colorado Health Sciences Center, Denver 80262.
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MeSH Terms
Citrate (si)-Synthase / physiology
Citrates* / blood,  cerebrospinal fluid,  urine
Folic Acid Deficiency / blood,  cerebrospinal fluid,  urine
Gas Chromatography-Mass Spectrometry
Kidney Diseases / blood,  cerebrospinal fluid,  urine
Middle Aged
Vitamin B 12 Deficiency* / blood,  cerebrospinal fluid,  urine
Grant Support
Reg. No./Substance:
0/Citrates; 6061-96-7/2-methylcitric acid; EC (si)-Synthase

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