Initial organic products of assimilation of (/sup 13/N)ammonium and (/sup 13/N)nitrate by tobacco cells cultured on different sources of nitrogen. [Glutamine]
Glutamine is the first major organic product of assimilation of /sup 13/NH/sub 4//sup +/ by tobacco (Nicotiana tabacum L. cv. Xanthi) cells cultured on nitrate, urea, or ammonium succinate as the sole source of nitrogen, and of /sup 13/NO/sub 3//sup -/ by tobacco cells cultured on nitrate. The percentage of organic /sup 13/N in glutamate, and subsequently, alanine, increases with increasing periods of assimilation. /sup 13/NO/sub 3//sup -/, used for the first time in a study of assimilation of nitrogen, was purified by new preparative techniques. During pulse-chase experiments, there is a decrease in the percentage of /sup 13/N in glutamine, and a concomitant increase in the percentage of /sup 13/N in glutamate and alanine. Methionine sulfoximine inhibits the incorporation of /sup 13/N from /sup 13/NH/sub 4//sup +/ into glutamine more extensively than it inhibits the incorporation of /sup 13/N into glutamate, with cells grown on any of the three sources of nitrogen. Azaserine inhibits glutamate synthesis extensively when /sup 13/NH/sub 4//sup +/ is fed to cells cultured on nitrate. These results indicate that the major route for assimilation of /sup 13/NH/sub 4//sup +/ is the glutamine synthetase-glutamate synthase pathway, and that glutamate dehydrogenase also plays a role, but a minor one. Methionine sulfoximine inhibits the incorporation of /sup 13/N from /sup 13/NO/sub 3//sup -/ into glutamate more strongly than it inhibits the incorporation of /sup 13/N into glutamine, suggesting that the assimilation of /sup 13/NH/sub 4//sup +/ derived from /sup 13/NO/sub 3//sup -/ may be mediated solely by the glutamine synthetase-glutamate synthase pathway.
- Research Organization:
- Michigan State Univ., East Lansing
- OSTI ID:
- 6777307
- Journal Information:
- Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 62; ISSN PLPHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
550500* -- Metabolism
59 BASIC BIOLOGICAL SCIENCES
AMIDES
AMINO ACIDS
AMMONIUM COMPOUNDS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
BIOSYNTHESIS
CARBOXYLIC ACIDS
CELL CULTURES
CRYOGENIC FLUIDS
CULTURE MEDIA
DEHYDROGENASES
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
ENZYMES
FLUIDS
GLUTAMINE
ISOTOPES
LIGHT NUCLEI
METABOLISM
MINUTES LIVING RADIOISOTOPES
NICOTIANA
NITRATES
NITROGEN
NITROGEN 13
NITROGEN COMPOUNDS
NITROGEN ISOTOPES
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PLANT CELLS
PLANTS
RADIOISOTOPES
SYNTHESIS