scholarly journals Exploring Platelet Chemokine Antimicrobial Activity: Nuclear Magnetic Resonance Backbone Dynamics of NAP-2 and TC-1

2011 ◽  
Vol 55 (5) ◽  
pp. 2074-2083 ◽  
Author(s):  
Leonard T. Nguyen ◽  
Paulus H. S. Kwakman ◽  
David I. Chan ◽  
Zhihong Liu ◽  
Leonie de Boer ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Antimicrobial Activity ◽  
Magnetic Resonance ◽  
Antimicrobial Activities ◽  
Backbone Dynamics ◽  
Dynamic Simulations ◽  
Model Free ◽  
Significant Difference ◽  
Carboxy Terminal ◽  
Nuclear Magnetic

ABSTRACTThe platelet chemokines neutrophil-activating peptide-2 (NAP-2) and thrombocidin-1 (TC-1) differ by only two amino acids at their carboxy-terminal ends. Nevertheless, they display a significant difference in their direct antimicrobial activities, with the longer NAP-2 being inactive and TC-1 being active. In an attempt to rationalize this difference in activity, we studied the structure and the dynamics of both proteins by nuclear magnetic resonance (NMR) spectroscopy. Using15N isotope-labeled protein, we confirmed that the two monomeric proteins essentially have the same overall structure in aqueous solution. However, NMR relaxation measurements provided evidence that the negatively charged carboxy-terminal residues of NAP-2 experience a restricted motion, whereas the carboxy-terminal end of TC-1 moves in an unrestricted manner. The same behavior was also seen in molecular dynamic simulations of both proteins. Detailed analysis of the protein motions through model-free analysis, as well as a determination of their overall correlation times, provided evidence for the existence of a monomer-dimer equilibrium in solution, which seemed to be more prevalent for TC-1. This finding was supported by diffusion NMR experiments. Dimerization generates a larger cationic surface area that would increase the antimicrobial activities of these chemokines. Moreover, these data also show that the negatively charged carboxy-terminal end of NAP-2 (which is absent in TC-1) folds back over part of the positively charged helical region of the protein and, in doing so, interferes with the direct antimicrobial activity.

scholarly journals Evaluating Gramicidin A Channel Backbone Dynamics by Molecular Dynamics and Nuclear Magnetic Resonance

2009 ◽  
Vol 96 (3) ◽  
pp. 152a-153a
Author(s):  
Helgi I. Ingolfsson ◽  
Vitaly V. Vostrikov ◽  
Hong Gu ◽  
Roger E. Koeppe ◽  
James F. Hinton ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Gramicidin A ◽  
Backbone Dynamics ◽  
Nuclear Magnetic

scholarly journals Nuclear Magnetic Resonance Study of Cerebrospinal Fluid From Patients With Multiple Sclerosis

1993 ◽  
Vol 20 (3) ◽  
pp. 194-198 ◽  
Author(s):  
Lynch Joanna ◽  
Peeling James ◽  
Auty Anthony ◽  
R. Sutherland Garnette
Keyword(s):  
Multiple Sclerosis ◽  
Nuclear Magnetic Resonance ◽  
Cerebrospinal Fluid ◽  
Magnetic Resonance ◽  
Progressive Multiple Sclerosis ◽  
Aids Dementia Complex ◽  
Proton Nuclear Magnetic Resonance ◽  
Significant Difference ◽  
Metabolite Concentrations ◽  
Nuclear Magnetic

ABSTRACT:Proton nuclear magnetic resonance (NMR) spectroscopy was used to examine cerebrospinal fluid (CSF) from patients (n = 30) with actively progressive multiple sclerosis (MS). Metabolite concentrations obtained from the spectra were compared to those determined from the spectra of CSF from control patients (n = 27) with benign spinal disorders. No significant difference was found between the 2 groups for most constituents, including lactate, glutamine, citrate, creatine and creatinine, and glucose. Acetate levels were significantly higher in MS patients, while formate levels were significantly lower, than the controls. There were no significant differences in metabolite concentrations in CSF from early and longstanding MS patients. A peak due to an unidentified compound was found at 2.82 ppm in the spectra of CSF from patients with actively progressive MS, but not in the spectra of CSF from the controls. The peak was not found in spectra of CSF from patients with AIDS dementia complex (n = 9) or Parkinson's disease (n = 5), but it did appear in spectra of CSF from 1 patient with Jakob-Creutzfeldt disease (out of 3 examined) and from 1 patient (out of 7) with Guillan-Barré disease. The unidentified compound is volatile and, from the chemical shift of the observed NMR peak, is probably an N-methyl compound. As such, it may be an intermediate in the cholino-glycine cycle, in which an abnormality has been proposed to exist in MS patients.

Water Dynamics of Mung bean (Vigna radiata) Sprouts Treated with 6-Benzylaminopurine: Discrimination by Low-Field Nuclear Magnetic Resonance and Spectrometry

2018 ◽  
Vol 14 (4) ◽  
Author(s):  
Zhuyi Lin ◽  
Ruiying Wang ◽  
Siqi Wang ◽  
Mingqian Tan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Mung Bean ◽  
Control Sample ◽  
Water Dynamics ◽  
Low Field ◽  
Significant Difference ◽  
Bean Sprouts ◽  
Lf Nmr ◽  
Nuclear Magnetic

AbstractMung bean sprouts are a kind of favorite healthy food across the world. As a forbidden plant hormone cytokinins, the use of 6-benzylaminopurine (6-BAP) in promoting the growth of bean sprouts is forbidden due to its safety concerns. Rapid analysis of 6-BAP treated bean sprouts is required to assess their growth changes and discriminate them from the normal sample. In this study, the water dynamics of growth for 6-BAP treated bean sprouts was monitored by the low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging. A simplified cartoon model of the water dynamics was proposed to explain the LF-NMR analysis result. Principal component analysis of the NMR relaxation data clearly showed the different water distribution of 6-BAP treated bean sprouts from the control sample. The juice of 6-BAP treated bean sprouts showed significant difference in the ultraviolet absorption and fluorescence spectra. Therefore, combining the spectrometry, the LF-NMR may have potential for rapid discrimination of the 6-BAP treated bean sprouts.

A novel carborane-containing ceramic precursor: Synthesis, characterization, and ceramic conversion mechanism

2018 ◽  
Vol 31 (6) ◽  
pp. 694-706 ◽  
Author(s):  
Dejin Tong ◽  
Haipeng Wang ◽  
Lei Chen ◽  
Lei Wang ◽  
Zhanxiong Li
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Oxidative Stability ◽  
Energy Demand ◽  
Proton Nuclear Magnetic Resonance ◽  
Gas Chromatography Mass Spectrometry ◽  
Linear Polymers ◽  
Model Free ◽  
Ft Ir ◽  
Nuclear Magnetic

Linear carborane-carbosilane-phenylacetylene polymers have been synthesized as precursors for ceramic and characterized by Fourier transform infrared (FT-IR), proton nuclear magnetic resonance (1H-NMR), and carbon-nuclear magnetic resonance (13C-NMR). Novel linear polymers have the advantage of being extremely easy to process and convert into ceramics, since they are either viscous liquids or low melting solids at room temperature and are soluble in most organic solvents. Ceramic conversion reaction of the polymers was studied, and the conversion mechanism using thermogravimetric analyzer, FT-IR, and pyrolysis-gas chromatography-mass spectrometry was proposed. During the early heating period in the mechanism, the precursor polymer is cured and oligomer is formed. Then the degradation of oligomer takes place at higher temperatures with the weak bond cleaved and cross-linked simultaneously. Ceramic yield of the polymer after heating up to 1000°C in nitrogen (N2) was 77.6%. The derived ceramics exhibit excellent thermal and thermo-oxidative stability, whose 5% mass loss temperature was identified to be 650°C in N2 and 665°C in air, respectively. Boron appears to be the key element to achieve the outstanding thermo-oxidative stability. The relevant kinetic data were obtained by two kinds of model-free-kinetic algorithms, differential Friedman and integral Kissinger–Akahira–Sunose. These two methods were combined to give the energy profile, which has been identified to be a function of the transformation degree ( α), since the energy demand at each degradation stage is different depending on α.

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