This study investigated the influence of nitrogen (N) fertilizer and straw on intact amino acid N uptake by soil microorganisms and the relationship between amino acid turnover and soil properties during the wheat growing season. A wheat pot experiment was carried out with three treatments: control (CK), N fertilizer (NF) and N fertilizer plus rice straw (NS). We used stable isotope compound-sp...

We have measured galactic λ3mm absorption spectra of HCO+, HCN, HNC, and CS toward compact extragalactic continuum sources in order to derive the isotopic abundance ratios 12C/13C, 14N/15N, 16O/18O, and 32S/34S in local diffuse clouds. For carbon, our data confirm recent results for the local ISM: we find 12C/13C = 59 ± 2. For nitrogen, we find 14N/15N = 237(−21,+27) consistent with the Solar v...

The isotopically enriched cyanide anion, (13C≡15N)−, has a great potential as the NMR probe of non-covalent interactions. However, hydrogen is highly toxic and can decompose explosively. It therefore desirable to be able theoretically estimate any valuable results certain experiments in advance order carry out experimental studies only for most suitable molecular systems. We report effect bondi...

The MutT protein, a 129-residue enzyme from Escherichia coli which prevents A.T-->C.G mutations, catalyzes the hydrolysis of nucleoside triphosphates (NTP) to nucleoside monophosphates (NMP) and pyrophosphate [Bhatnagar, S. K., Bullions, L. C., & Bessman, M. J. (1991) J. Biol. Chem. 266, 9050-9054], by a mechanism involving nucleophilic substitution at the rarely attacked beta-phosphorus of NTP...

Clean MAS observation of 13C-labeled carbons in membrane-bound HIV-1 and influenza fusion peptides was made by using a rotational-echo double-resonance spectroscopy (REDOR) filter of directly bonded 13C-15N pairs. The clean filtering achieved with the REDOR approach is superior to filtering done with sample difference spectroscopy. In one labeling approach, the peptide had labels at a single 13...

A modified version of the JHH-TOCSY experiment, 'signed COSY', is presented that allows the determination of the sign of residual dipolar 1H-1H coupling constants with respect to the sign of one-bond 1H-X coupling constants in linear three-spin systems X-1H-1H, where X = 13C or 15N. In contrast to the original JHH-TOCSY experiments, the signs of J(HH) couplings may be determined for CH2-CH2 moi...

Dynamic Nuclear Polarization (DNP) is often achieved by the direct transfer of polarization from electrons to nuclei such as 13C, induced by microwave saturation of the wings of narrow EPR lines of radicals like trityl. In the indirect approach on the other hand, DNP is used to transfer the polarization from the electrons of radicals such as nitroxides that have broad EPR lines to nuclear spins...

Mass blooms of purple sulfur bacteria growing seasonally on green stranded macroalgae have a major impact on the microbial composition and functionality of intertidal mats. To explore the active anoxygenic phototrophic community in purple bacterial mats from the Roscoff Aber Bay (Brittany, France), we conducted a combined approach including molecular and high-resolution secondary ion mass spect...

The solution structure of the ribonuclease H domain of HIV-1 reverse transcriptase has been investigated by three-dimensional double and triple resonance heteronuclear magnetic resonance spectroscopy. The domain studied has 138 residues and comprises residues 427 to 560 of the 66 kDa reverse transcriptase with an additional four residues at the N terminus. Initial studies on the wild-type prote...