The nitrogen isotope composition (δ¹⁵N) of different amino acids carries different dietary information. We hypothesized that transamination and de novo synthesis create three groups that largely explain their dietary information. Rats were fed with ¹⁵N-labeled amino acids. The redistribution of the dietary ¹⁵N labels among the muscular amino acids was analyzed. Subsequently, the labeling was ch...

The incorporation of isotopic nitrogen from N15-aspartic acid, N15-glutamic acid, or N15(amide nitrogen)-glutamine into the nitrogens of the pyrimidine ring of hypoxanthine synthesized from glycine-l-Cl4 in pigeon liver extracts has been reported to be approximately equivalent to the incorporation of Cl4 from labeled glycine (1). It was proposed that biological similarity of the transaminating ...

Here we report the first experimental detection of the Cs symmetric nitroformyl radical, OCNO(X A00) in a nitrogen–carbon dioxide matrix at 10 K using a Fourier transform infrared spectrometer (FTIR). The n1 vibrational frequency was observed at 2113 cm . This assignment was confirmed by follow-up experiments using isotopically labeled reactant molecules (N, O, C). To synthesize this radical, w...

Cloned nitrogen fixation (nifl) genes from Klebsiella pneumoniae hybridize to DNA from 19 out of 19 widely divergent nitrogen-fixing bacterial strains but do not hybridize to DNA from 10 different non-nitrogen-fixing species. K pneumoniae nifDNA fragments that hybridize to DNA from other species contain part of the three structural genes that code for nitrogenase polypeptides. We have utilized ...

Cloned nitrogen fixation (nifl) genes from Klebsiella pneumoniae hybridize to DNA from 19 out of 19 widely divergent nitrogen-fixing bacterial strains but do not hybridize to DNA from 10 different non-nitrogen-fixing species. K pneumoniae nifDNA fragments that hybridize to DNA from other species contain part of the three structural genes that code for nitrogenase polypeptides. We have utilized ...

Heavy nitrogen (N2) 1 is often used as a label for nitrogen Wxation experiments in which it is desirable to monitor directly the rate of nitrogen Wxation and the destination of the resulting metabolites in an organism or ecosystem [1–4]. Heavy nitrogen can be purchased in a pressurized cylinder or produced in the laboratory with specialized equipment, but both methods of obtaining the gas are e...

Since its release for routine clinical use, (99m)Tc-mercaptoacetyltriglycine (MAG3) has become an important alternative to (131)I-labeled orthoiodohippuran. The cold kit for MAG3 is expensive, especially in developing countries. Therefore, unique storage conditions should be provided for cost reduction. Cold fractioning is a well-known procedure but has special requirements, such as a nitrogen ...

Plant roots incorporate inorganic nitrogen into the amino acids glutamine, glutamic acid, asparagine and aspartic acid, which together serve as the primary metabolites of nitrogen transport to other tissues. Given the preponderance of these four amino acids, phloem sap is a nutritionally unbalanced diet for phloem-feeding insects. Therefore, aphids and other phloem feeders typically rely on mic...

The 1H and 15N NMR spectra of several 15N-labeled pyridoxal-5'-phosphate model systems have been measured at low temperature in various aprotic and protic solvents of different polarity, i.e., dichloromethane-d2, acetonitrile-d3, tetrahydrofuran-d8, freon mixture CDF3/CDClF2, and methanol. In particular, the 15N-labeled 5'-triisopropyl-silyl ether of N-(pyridoxylidene)-tolylamine (1a), N-(pyrid...