• Journal of the Korean Magnetic Resonance Society
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• v.25 no.4
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• pp.64-69
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• 2021

In the developed NMR hyperpolarization techniques, Signal amplification by reversible exchange (SABRE) technique is thought to be a promising method to overcome the low sensitivity of bio-NMR/MRI. Most experiments using SABRE have been done in methanol, which is biologically harmful solvent. Therefore, more biological friendly solvent, such as ethanol can be more appropriate solvent to be applicable in bio-NMR and MRI. As the proof of concept, successful hyperpolarization on pyridine via SABRE is carried out in ethanol and its enhancement factor is calculated to be more than 150 folds. To investigate more about its possibility of hyperpolarization in different alcohol solvents, methanol and propanol are used for SABRE in the same condition. The overall polarization trend in different external magnetic field is similar but its polarization number is decreased with higher molecular weight solvents (the order from methanol to propanol). This result indicates that the efficiency of SABRE is different from solvent system despite its same functional group and similar properties. Higher para-hydrogen concentration, higher partial pressure of para-hydrogen, and deuterated solvent can increase the hyperpolarization in any solvents. With these series of successful SABRE results, future studies on SABRE in more biofriendly environment, on more various solvent systems, and with more substrates are needed and it will be the firm basis for applying the SABRE system on the future bio-NMR/MRI.

• 한국초전도학회:학술대회논문집
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• 2009.07a
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• pp.2-2
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• 2009

• Analytical Science and Technology
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• v.7 no.4
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• pp.505-515
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• 1994

$^1H$ NMR spectra for monocyanide ligated ferriprotoporphyrin(hemin) complex and dicyanide coordinated hemin complex in dimethylsulfoxide(DMSO-$d_6$) solution have been recorded and analyzed. NMR spectra of hemin-cyanide complexation in DMSO-$d_6$ exhibit that the cyanide ligation to hemin is temperature-dependent. Thermodynamic parameters for the monocyanide ligated hemin to dicyanide ligated hemin are consistent with endothermic process with ${\Delta}H^{\circ}=736.6cal/mol$ and ${\Delta}S^{\circ}=16.4eu$. Detailed analysis of the anomalous deviation from Curie behavior for CN/DMSO coordinated hemin complex demonstrates the presence of a high spin character, and this weaker axial field relative to the purely low-spin dicyanide hemin complex is supposed to attribute to instantaneously ruptured iron-DMSO bond. This complex may serve as a useful model to characterize electronic/molecular structure of hemoproteins, which one of axial ligands is weak.

• Progress in Superconductivity and Cryogenics
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• v.15 no.2
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• pp.20-23
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• 2013

For sensitive measurements of micro-Tesla nuclear magnetic resonance (${\mu}T$-NMR) signal, a low-noise superconducting quantum interference device (SQUID) system is needed. We have fabricated a liquid He dewar for an SQUID having a large diameter for the pickup coil. The initial test of the SQUID system showed much higher low-frequency magnetic noise caused by the thermal magnetic noise of the aluminum plates used for the vapor-cooled thermal shield material. The frequency dependence of the noise spectrum showed that the noise increases with the decrease of frequency. This behavior could be explained from a two-layer model; one generating the thermal noise and the other one shielding the thermal noise by eddy-current shielding. And the eddy-current shielding effect is strongly dependent on the frequency through the skin-depth. To minimize the loop size for the fluctuating thermal noise current, we changed the thermal shield material into insulated thin Cu mesh. The magnetic noise of the SQUID system became flat down to 0.1 Hz with a white noise of 0.3 $fT/{\surd}Hz$, including the other noise contributions such as SQUID electronics and magnetically shielded room, etc, which is acceptable for low-noise ${\mu}T$-NMR experiments.

• 한국초전도학회:학술대회논문집
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• 2009.07a
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• pp.66-66
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• 2009

• 한국초전도학회:학술대회논문집
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• 2009.07a
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• pp.72-72
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• 2009

• 한국초전도학회:학술대회논문집
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• 2009.07a
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• pp.10-10
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• 2009

• Proceedings of the Korean Society of Applied Pharmacology
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• 1997.04a
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• pp.86-86
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• 1997

Human annexin I is a member of annexin family of calcium dependent phospholipid binding proteins, which have been implicated in various physiological roles including phospholipase A$_2$ (PLA$_2$) inhibition, membrane fusion and calcium channel activity. In this work, the structure of N-terminally truncated human annexin I (Δ-annexin I) and its interactions with Ca$\^$2+/, ATP and cAMP were studied at atomic level by using $^1$H, $\^$15/N, $\^$l3/C NMR (nuclear magnetic resonance) spectroscopy. The effect of Ca$\^$2+/ binding on the structure of Δ-annexin I was investigated, and compared with that of Mg$\^$2+/ binding. The addition of Ca$\^$2+/ to Δ-annexin I caused some changes in the high field and low field regions of $^1$H NMR spectra. Whereas, upon addition of Mg$\^$2+/ to Δ-annexin I, almost no change could be observed. Also we found that the binding ratio of ATP to Δ-annexin I is 1. Because Δ-annexin I is a large protein with 35 kDa molecular weight, site-specific (carbonyl-$\^$l3/C, amide-$\^$15/N) labeling technique was used to determine the interaction sites of Δ-annexin I with Ca$\^$2+/ and ATP. Assignments of all the histidinyl carbonyl carbon resonances have been completed by using Δ-annexin I along with its specific 1,2-subdomain. The carbonyl carbon resonances originating from His52 and His246 of Δ-annexin I were significantly affected by Ca$\^$2+/ binding, and some Tyr and Phe resonances were also affected. The carbonyl carbon resonances originating from His52 is significantly affected by ATP binding, therefore His52 seems to be involved in the ATP binding site of Δ-annexin I.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.182-182
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• 1996

Annexin I is a member of the annexin family of calcium dependent phospholipid binding proteins and has anti-inflammatory activity by inhibiting phospholipase A$_2$ (PLA$_2$). Recent X-ray crystallographic study of annexin I identified six Ca$\^$2+/ binding bites, which was different types (type II, III) from the well-known EF-hand motif (type I). In this work, the structure of annexin I was studied at atomic level by using $^1$H, $\^$15/N and $\^$l3/C NMR(nuclear magnetic resonance) spectroscopy, and the effect of Ca$\^$2+/ binding on the structure of annexin I was studied, and compared with that of Mg$\^$2+/ binding, When Ca$\^$2+/ was added to annexin I, NMR peak change was occured in high- and low-field regions of $^1$H-NMR spectra. NMR peak change by Ca$\^$2+/ binding was different from that by Mg$\^$2+/ binding. Because annexin I is a larger protein with 35 kDa molecular weight, site-specific (amide-$\^$15/N, carbonyl-$\^$l3/C) labeling technique was also used. We were able to detect methionine, tyrosine and phenylalanine peaks respectively in $\^$13/C-NMR spectra, and each residue was able to be assigned by the method of doubly labeling annexin I with [$\^$13/C] carbonyl-amino acid and [$\^$15/N] amide-amino acid. In $\^$l3/C-NMR spectra of [$\^$13/C] carbonyl-Met labeled annexin I, we observed that methionine residues spatially located near Ca$\^$2+/ binding Sites Were Significantly effected by Ca$\^$2+/ binding. From UV spectroscopic data on the effect of Ca$\^$2+/ binding, we knew that Ca$\^$2+/ binding sites of annexin I have cooperativity in Ca$\^$2+/ binding. The interaction of annexin I with PLA$_2$ also could be detected by using heteronuclear NMR spctroscopy. Consequently, we expect that the anti-inflammatory action mechanism of annexin I may be a specific protein-protein interaction. The residues involved in the interaction with PLA$_2$ can be identified as active site by assigning NMR peaks effected by PLA$_2$ binding.

• Korean Journal of Food Science and Technology
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• v.41 no.3
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• pp.292-295
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• 2009

To discriminate the geographical origin (Korea vs. China) of soybean (Glycine max(L.) merrill) samples (Korean samples n=25, Chinese samples n=24), proximate composition of soybeans and relaxation times were analyzed using low field NMR. Composition results indicate that there are no significant differences in moisture, fat, or ash contents between soybeans. The crude protein content of Korean soybeans, however, was higher than that of Chinese soybeans (p<0.05). The relaxation times of T1-IR (p<0.0001), T1-SR (p<0.0001), and T2-SE (p<0.0086) in Korean soybeans were longer than those in Chinese soybeans. The geographical origin of soybeans could be identified using a canonical discriminant analysis using two relaxation times (T1-IR and T1-SR) with 96% accuracy. Furthermore, in this study, a canonical discriminant analysis using four relaxation times (T1-IR, T1-SR, T2-SE, and T2-CPMG) could discriminate the geographical origin with 100% accuracy. It was possible to identify the geographical origin of Korean and Chinese soybeans using relaxation times from 10 MHz NMR.