Enzymatic synthesis of (N-13) or (C-11) carbamyl phosphate and their use for labeling metabolites of the urea cycle and the pyrimidine nucleotide pathway
Carbamyl phosphate (CP) serves as a precursor for the synthesis of metabolites of the urea cycle and the de novo pyrimidine nucleotide pathway. CP is enzymatically formed from ATP, NH/sub 4//sup +/ and HCO/sub 3-/ by carbamyl phosphate synthetase (CPS). By utilizing CPS purified from E. coli and by adding (N-13) ammonia or (C-11) carbon dioxide to the reaction mixture the authors have incorporated either label into CP, as demonstrated by cation exchange HPLC analyses. Co-immobilization of CPS with either ornithine transcarbamylase or aspartate transcarbamylase onto CNBr-activated Sepharose resulted in the synthesis of L-(..omega..-N-13) citrulline or L-(carbamyl-n-13) carbamyl aspartate, respectively. Carbamyl L-(N-13) aspartate has also been synthesized from L-(N-13) aspartate and CP using immobilized aspartate transcarbamylase. In this case labeled aspartate was prepared by passage of (N-13) ammonia through columns containing immobilized glutamate dehydrogenase and glutamate-oxaloacetate transaminase. Tissue distribution studies were carried out in melanoma-bearing mice. Five minutes after retro-orbital venous injection of (N-13) CP, tumor uptake of label was observed. Concentration of activity from CP ws 2-3 times higher in heart but 30% lower in liver and 80% lower in pancreas when compared with (N-13) leucine and methionine. This study illustrates the feasibility of labeling metabolites in different molecular positions with N-13 or C-11 by use of immobilized multi-enzyme systems.
- Research Organization:
- Memorial Sloan-Kettering Cancer Center, New York, NY
- OSTI ID:
- 6780738
- Report Number(s):
- CONF-840619-
- Journal Information:
- J. Nucl. Med.; (United States), Journal Name: J. Nucl. Med.; (United States) Vol. 25:5; ISSN JNMEA
- Country of Publication:
- United States
- Language:
- English
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62 RADIOLOGY AND NUCLEAR MEDICINE
AMIDES
AMINO ACIDS
AMMONIA
ANIMALS
ATP
AZINES
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BIOLOGICAL PATHWAYS
BIOSYNTHESIS
BODY
CARBON 11
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON ISOTOPES
CARBON OXIDES
CARBONIC ACID DERIVATIVES
CARBOXYLIC ACIDS
CARDIOVASCULAR SYSTEM
CHALCOGENIDES
CHROMATOGRAPHY
CITRULLINE
COUNTING TECHNIQUES
DIAGNOSIS
DIAGNOSTIC USES
DIGESTIVE SYSTEM
DISEASES
DISTRIBUTION
ELECTRON CAPTURE RADIOISOTOPES
ENDOCRINE GLANDS
EVEN-ODD NUCLEI
GLANDS
HEART
HETEROCYCLIC COMPOUNDS
HYDRIDES
HYDROGEN COMPOUNDS
INJECTION
INTAKE
INTRAVENOUS INJECTION
ISOTOPES
LABELLING
LIGHT NUCLEI
LIQUID COLUMN CHROMATOGRAPHY
LIVER
MAMMALS
MELANOMAS
METABOLITES
MICE
MINUTES LIVING RADIOISOTOPES
NEOPLASMS
NITROGEN 13
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NITROGEN ISOTOPES
NUCLEI
NUCLEOTIDES
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
OXIDES
OXYGEN COMPOUNDS
PANCREAS
PHOSPHATES
PHOSPHORUS COMPOUNDS
PYRIMIDINES
QUANTITY RATIO
RADIOISOTOPE SCANNING
RADIOISOTOPES
RODENTS
SEPARATION PROCESSES
SYNTHESIS
TISSUE DISTRIBUTION
UPTAKE
UREA
USES
VERTEBRATES