Quantitative NMR, Methods and Applications

Background: NMR spectroscopy is one of the most powerful tools to study the structure and interaction properties of peptides and proteins from a dynamic perspective. Knowing the bioactive conformations of peptides is crucial in the drug discovery field to design more efficient analogue ligands and inhibitors of protein-protein interactions targeting therapeutically relevant systems. Objective: This review provides a toolkit to investigate peptide conformational properties by NMR. Methods: Articles cited herein, related to NMR studies of peptides and proteins were mainly searched through Pubmed and the web. More recent and old books on NMR spectroscopy written by eminent scientists in the field were consulted as well. Results: The review is mainly focused on NMR tools to gain the 3D structure of small unlabeled peptides. It is more application-oriented as it is beyond its goal to deliver a profound theoretical background. However, the basic principles of 2D homonuclear and heteronuclear experiments are briefly described. Protocols to obtain isotopically labeled peptides and principal triple resonance experiments needed to study them, are discussed as well. Conclusion: NMR is a leading technique in the study of conformational preferences of small flexible peptides whose structure can be often only described by an ensemble of conformations. Although NMR studies of peptides can be easily and fast performed by canonical protocols established a few decades ago, more recently we have assisted to tremendous improvements of NMR spectroscopy to investigate instead large systems and overcome its molecular weight limit.

Download Full-text

Novel Products in the CO2-Laser Induced Reaction of Trichloroethylene

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19950104 ◽

1995 ◽

Vol 60 (1) ◽

pp. 104-114 ◽

Cited By ~ 6

Author(s):

Boyd L. Earl ◽

Richard L. Titus

Keyword(s):

Irradiation Time ◽

Product Distribution ◽

Incident Power ◽

Cell Geometry ◽

Reaction Conditions ◽

Peak Areas ◽

Induced Decomposition ◽

Nmr Methods ◽

Induced Reaction ◽

Novel Products

Previous reports on the thermal or CO2-laser induced decomposition of trichloroethylene have identified only one condensible product, hexachlorobenzene (in addition to HCl and mono- and dichloroacetylene). We have found that trichloroethylene vapor exposed to cw irradiation on the P(24) line of the (001 - 100) band of the CO2 laser at incident power levels from 8 - 17 W produces numerous products, of which the 13 major ones have been identified using IR, GC/MS, GC/FTIR, and NMR methods. All of these products have 4, 6, or 8 carbons, are highly unsaturated, and are completely chlorinated or contain a single hydrogen. C4HCl5 and C6Cl6 isomers (three of each) account for S 55% to 85% of total products (based on peak areas in the total ion chromatograms in GC/MS runs), depending on reaction conditions. In addition to characterizing the products, we discuss the dependence of the product distribution on laser power, irradiation time, and cell geometry, and we outline a possible mechanism.

Download Full-text

(S)-1-(Ethoxycarbonyl)ethyl(2R,5S)-2,5-dimethyl-1,3-dioxolan-4-one-2-carboxylate

Molbank ◽

10.3390/m1178 ◽

2021 ◽

Vol 2021 (1) ◽

pp. M1178

Author(s):

R. Aitken ◽

Oliver Haslett ◽

Alexandra Slawin

Keyword(s):

Lactic Acid ◽

Title Compound ◽

Ethyl Pyruvate ◽

X Ray Diffraction ◽

X Ray ◽

Nmr Methods

The title compound was obtained in low yield in the condensation of ethyl pyruvate and lactic acid. Its structure is determined by NMR methods and x-ray diffraction and the mechanism for formation of this 1:2 adduct from the initial 1:1 adduct is considered.

Download Full-text