In recent years, a number of magic-angle spinning (MAS) solidstate nuclear magnetic resonance (SSNMR) methods have been developed1 for 13C and 15N resonance assignments in uniformly 13C,15N-labeled peptides and proteins.2 The 13CO, 13CR, 13Câ, and amide 15N chemical shifts can be used to estimate the backbone torsion angles φ and ψ.3 Additional constraints on the local structure in U-13C,15N-la...

The glycosaminoglycan hyaluronan is a vital structural component of extracellular matrices with diverse biological functions, a molecular understanding of which requires a detailed description of secondary and tertiary solution structures. Various models of these structures have been proposed on the basis of 1H and 13C natural-abundance nuclear magnetic resonance (NMR) experiments, but resonanc...

been studied for R=Me, Et, i-Pr, and Ph. The reactions are studied by 15N and 31p NMR spectroscopy. Two 31p NMR resonances were observed for R3PAuCN and (R3P)2Au+ species. However, for the 15N NMR, only averaged resonances were observed for R3PAuC15N and Au(C15N)2" species except for Et3PAuC15N, where two resonances were detected.The R3PAu13C15N complexes have also been prepared where R= Me, Et...

By simultaneously incorporating in a protein 13C-carbonyl- and 15N-labeled amino acids with different levels of enrichment, characteristics asymmetric doublet-like patterns are observed for 15N nuclei that are directly adjacent to the 13C1-labeled residues, providing unambiguous identification of a large number of unique dipeptide fragments of the protein. Additional assignments and qualitative...

13C and 15N photo-CIDNP effects were determined for the reversible electron transfer from pyrene to arene diazonium salts on excitation of the charge transfer band at 360 nm. The diazonium salts being the products of back electron transfer ("cage products") show enhanced absorption for 13C(1) and the 15N-enriched diazonium group, whereas the escape products, ArH or löN2, respectively, yield emi...

The use of uniformly 13C,15N-labeled RNA has greatly facilitated structural studies of RNA oligonucleotides by NMR. Application of similar methodologies for the study of DNA has been limited, primarily due to the lack of adequate methods for sample preparation. Methods for both chemical and enzymatic synthesis of DNA oligonucleotides uniformly labeled with 13C and/or 15N have been published, bu...

Resource utilization by earthworms affects soil C and N dynamics and further colonization of invasive earthworms. By applying 13C-labeled Tabebuia heterophylla leaves and 15N-labeled Andropogon glomeratus grass, we investigated resource utilization by three earthworm species (invasive endogeic Pontoscolex corethrurus, native anecic Estherella sp., and native endogeic Onychochaeta borincana) and...

Objective chemical biomarkers are needed in clinical studies of diet-related diseases to supplement subjective self-reporting methods. We report on several critical experiments for the development of clinically legitimate dietary stable isotope biomarkers within human blood. Our examination of human blood revealed the following: (1) Within blood clot and serum from anonymous individuals (201 ma...