증식성 초자체 망막증에 대한 초자체 절제술의 효과 : 제1보:초자체 절제술을 받은 망막박리 422눈에 대한 임상적 분석

이재홍,임진옥 최신의학사 1994 最新醫學 Vol.37 No.4

Geminate rebinding dynamics of nitric oxide to ferric hemoglobin in D2O solution.

Park, Jaeheung,Lee, Taegon,Lim, Manho Royal Society of Chemistry 2013 PHOTOCHEMICAL AND PHOTOBIOLOGICAL SCIENCES Vol.12 No.6

<P>Femtosecond mid-infrared (mid-IR) spectroscopy was used to probe geminate rebinding (GR) dynamics of photo-released nitric oxide (NO) to ferric hemoglobin (Hb(III)) in D2O solution at room temperature. Time-resolved vibrational spectra exhibit two overlapping NO bands for NO-bound Hb(III) (Hb(III)NO), a major band at 1925 cm(-1) (89%) and a minor one at 1905 cm(-1) (11%), suggesting that Hb(III)NO has at least two conformational substates. Both bands decay nonexponentially, each with a different time scale, and the decays are described by a stretched exponential function; the major band's decay is described by 0.96 exp(-t/40 ps)(0.86) + 0.04 and the minor band's decay is described by exp(-t/85 ps)(0.75). These decays arise mainly from the GR of the photo-released NO to Hb(III), indicating that the bound state's conformer influences the NO binding. In particular, the His64 residue, known to have inward conformation in the major band and outward conformation in the minor band, plays a significant role in controlling the binding of NO to Hb(III). The GR of NO to ferric Hb is slower than that to ferrous Hb, which shows fast and efficient GR due to the high reactivity of NO to the heme Fe(ii). The slower GR of NO to Hb(III) may be caused by the lower reactivity of NO to the heme Fe(iii).</P>

Structure and reactivity of a mononuclear non-haem iron(III)??peroxo complex

Cho, Jaeheung,Jeon, Sujin,Wilson, Samuel A.,Liu, Lei V.,Kang, Eun A.,Braymer, Joseph J.,Lim, Mi Hee,Hedman, Britt,Hodgson, Keith O.,Valentine, Joan Selverstone,Solomon, Edward I.,Nam, Wonwoo Nature Publishing Group, a division of Macmillan P 2011 Nature Vol.478 No.7370

Oxygen-containing mononuclear iron species??iron(iii)??peroxo, iron(iii)??hydroperoxo and iron(iv)??oxo??are key intermediates in the catalytic activation of dioxygen by iron-containing metalloenzymes. It has been difficult to generate synthetic analogues of these three active iron??oxygen species in identical host complexes, which is necessary to elucidate changes to the structure of the iron centre during catalysis and the factors that control their chemical reactivities with substrates. Here we report the high-resolution crystal structure of a mononuclear non-haem side-on iron(iii)??peroxo complex, [Fe(iii)(TMC)(OO)]<SUP>+</SUP>. We also report a series of chemical reactions in which this iron(iii)??peroxo complex is cleanly converted to the iron(iii)??hydroperoxo complex, [Fe(iii)(TMC)(OOH)]<SUP>2+</SUP>, via a short-lived intermediate on protonation. This iron(iii)??hydroperoxo complex then cleanly converts to the ferryl complex, [Fe(iv)(TMC)(O)]<SUP>2+</SUP>, via homolytic O??O bond cleavage of the iron(iii)??hydroperoxo species. All three of these iron species??the three most biologically relevant iron??oxygen intermediates??have been spectroscopically characterized; we note that they have been obtained using a simple macrocyclic ligand. We have performed relative reactivity studies on these three iron species which reveal that the iron(iii)??hydroperoxo complex is the most reactive of the three in the deformylation of aldehydes and that it has a similar reactivity to the iron(iv)??oxo complex in C??H bond activation of alkylaromatics. These reactivity results demonstrate that iron(iii)??hydroperoxo species are viable oxidants in both nucleophilic and electrophilic reactions by iron-containing enzymes.

Photoexcitation Dynamics of NO-Bound Ferric Myoglobin Investigated by Femtosecond Vibrational Spectroscopy

Park, Jaeheung,Lee, Taegon,Park, Jaehun,Lim, Manho American Chemical Society 2013 The journal of physical chemistry. B, Condensed ma Vol.117 No.10

<P>Femtosecond vibrational spectroscopy was used to investigate the photoexcitation dynamics of NO-bound ferric myoglobin (Mb<SUP>III</SUP>NO) in D<SUB>2</SUB>O solution at 294 K after excitation with a 575 nm pulse. The stretching mode of NO in Mb<SUP>III</SUP>NO consists of a major band at 1922 cm<SUP>–1</SUP> (97.7%) and a minor band at 1902 cm<SUP>–1</SUP> (2.3%), suggesting that Mb<SUP>III</SUP>NO in room temperature solution has two conformational substates. The time-resolved spectra show small but significant new absorption features at the lower-energy side of the main band (1920–1800 cm<SUP>–1</SUP>). One new absorption feature in the region of 1920–1880 cm<SUP>–1</SUP> exhibits the <SUP>15</SUP>NO isotope shift (37 cm<SUP>–1</SUP>) the same as that of the NO band in the ground electronic state of Mb<SUP>III</SUP>NO. This absorption shifts toward higher energy and narrows with a time constant of 2.4 ps, indicating that it evolves with rapid electronic and thermal relaxation of the photoexcited Mb<SUP>III</SUP>NO without photodeligation of the NO from the heme. Absorption features assigned to proteins undergoing thermal relaxation without NO deligation add up to 14 ± 1% of the total bleach, implying that the photolysis quantum yield of Mb<SUP>III</SUP>NO with a Q-band excitation is ≤0.86 ± 0.01. The remaining absorption bands peaked near 1867, 1845, and 1815 cm<SUP>–1</SUP>, each showing the <SUP>15</SUP>NO isotope shift the same as that of the free NO radical (33 cm<SUP>–1</SUP>), were assigned to the vibrational band of the photodeligated NO, the NO band of Mb<SUP>III</SUP>NO in an intermediate electronic state with low-spin Fe(III)–NO(radical) character (denoted as the R state), and the NO band of the vibrationally excited NO in the R state, respectively. A kinetics model successfully reproducing the time-dependent intensity changes of the transient bands suggests that every rebound NO forms the R state that eventually relaxes into the ground electronic state nonexponentially. Most of the photodissociated NO undergoes fast geminate recombination (GR), and the rebinding kinetics depends on the conformation of the protein. GR of NO to Mb<SUP>III</SUP> in the major conformation shows highly nonexponential kinetics described by a stretched exponential function, exp(−(<I>t</I>/290 ps)<SUP>0.44</SUP>. The NO rebinding to Mb<SUP>III</SUP> in the minor conformation is exponential, exp(−<I>t</I>/1.8 ns), suggesting that the distal histidine, the interaction of which dictates the conformation of Mb<SUP>III</SUP>NO, participates in mediating the binding of NO to Mb<SUP>III</SUP>. In Mb<SUP>III</SUP>NO, the elusive low-spin Fe(III)–NO(radical) state, proposed in electronic structure calculations, indeed exists at >12 kJ/mol above the ground state and takes part in the bond formation of Fe(III)–NO, suggesting that it plays a significant role in the function of NO-bound ferric protein. Time-resolved vibrational spectra with high sensitivity reveal rich photophysical and photochemical processes of photoexcited Mb<SUP>III</SUP>NO.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcbfk/2013/jpcbfk.2013.117.issue-10/jp400055d/production/images/medium/jp-2013-00055d_0013.gif'></P>

A fluorescence turn-on H₂O₂ probe exhibits lysosome-localized fluorescence signals

Song, Dayoung,Lim, Jung Mi,Cho, Somin,Park, Su-Jin,Cho, Jaeheung,Kang, Dongmin,Rhee, Sue Goo,You, Youngmin,Nam, Wonwoo The Royal Society of Chemistry 2012 Chemical communications Vol.48 No.44

<P>A new fluorescence turn-on probe that responds exclusively to H<SUB>2</SUB>O<SUB>2</SUB> exhibits subcellular localized fluorescence staining of lysosomes.</P> <P>Graphic Abstract</P><P>A new fluorescence turn-on sensor that responds exclusively to H<SUB>2</SUB>O<SUB>2</SUB> exhibits subcellular localized fluorescence staining of lysosomes. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cc31632c'> </P>

Excited-state energy relaxation dynamics of triply linked Zn(<small>II</small>) porphyrin arrays

Kim, Pyosang,Ikeda, Toshiaki,Lim, Jong Min,Park, Jaeheung,Lim, Manho,Aratani, Naoki,Osuka, Atsuhiro,Kim, Dongho Royal Society of Chemistry 2011 Chemical communications Vol.47 No.15

<P>In this study, we have investigated the excited-state energy deactivation dynamics of extended π-conjugated molecular systems that consist of competitive electronic and vibrational relaxation processes.</P> <P>Graphic Abstract</P><P>We have investigated the excited-state energy deactivation dynamics of extended π-conjugated molecular systems that consist of competitive electronic and vibrational relaxation dynamics. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1cc10521c'> </P>

Identification of an emitting molecular species by time-resolved fluorescence applied to the excited state dynamics of pigment yellow 101

Lee, Seung Noh,Park, Jaeheung,Lim, Manho,Joo, Taiha The Royal Society of Chemistry 2014 Physical chemistry chemical physics Vol.16 No.20

<P>Time-resolved fluorescence (TRF) with a resolution higher than the periods of vibrations may provide the vibrational spectrum of an emitting species by directly recording the vibrational wave packet motions in time. We applied high-resolution TRF to investigate the excited-state dynamics of pigment yellow 101 (P.Y.101). The TRF spectra of P.Y.101 in dichloromethane showed that upon photoexcitation of the enol isomer, dynamics occur in the S<SUB>1</SUB> state to form a product in two time constants at 30 and 140 fs. TRF signals were modulated due to the vibrational wave packet motions in the excited states, which provided the vibrational spectra of the emitting species. Depending on the emission wavelength, two different vibrational spectra were evident. With the help of theoretical calculations, the two spectra were assigned to the enol and keto isomers of P.Y.101 in the S1 state, leading to the conclusion that P.Y.101 undergoes ultrafast excited-state intramolecular proton transfer (ESIPT) with a quantum yield close to 1. Visible-pump infrared-probe transient absorption spectra were recorded to corroborate this conclusion.</P> <P>Graphic Abstract</P><P>Time-resolved fluorescence (TRF) with a resolution higher than the periods of vibrations may provide the vibrational spectrum of an emitting species by directly recording the vibrational wave packet motions in time. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3cp54546f'> </P>

Direct Observation of Ligand Rebinding Pathways in Hemoglobin Using Femtosecond Mid-IR Spectroscopy

Kim, Seongheun,Park, Jaeheung,Lee, Taegon,Lim, Manho American Chemical Society 2012 The Journal of physical chemistry B Vol.116 No.22

<P>The dynamics of NO rebinding in hemoglobin (Hb) was directly observed using femtosecond mid-IR spectroscopy after photodeligation of NO from HbNO in D<SUB>2</SUB>O at 283 K. Time-resolved spectra of bound NO appeared to have a single feature peaked at 1616 cm<SUP>–1</SUP> but were much better described by two Gaussians with equal intensities but different rebinding kinetics, where the feature at 1617 cm<SUP>–1</SUP> rebinds faster than the one at 1614 cm<SUP>–1</SUP>. It is possible that the two bands each correspond to one of two subunit constituents of the tetrameric Hb. Transient absorption spectra of photodeligated NO revealed three evolving bands near 1858 cm<SUP>–1</SUP> and their red-shifted replicas. The red-shifted replicas arise from photodeligated NO in the vibrationally excited <I>v</I> = 1 state. More than 10% of the NO was dissociated into the vibrationally excited <I>v</I> = 1 state when photolyzed by a 580 nm pulse. The three absorption bands for the deligated NO could be attributed to three NO sites in or near the heme pocket. The kinetics of the three transient bands for the deligated NO, as well as the recovery of the bound NO population, was most consistent with a kinetics scheme that incorporates time-dependent rebinding from one site that rapidly equilibrates with the other two sites. The time dependence results from a time-dependent rebinding barrier due to conformational relaxation of protein after deligation. By assigning each absorption band to a site in the heme pocket of Hb, a pathway for rebinding of NO to Hb was proposed.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcbfk/2012/jpcbfk.2012.116.issue-22/jp3026495/production/images/medium/jp-2012-026495_0001.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp3026495'>ACS Electronic Supporting Info</A></P>

Dynamics of Geminate Rebinding of CO to Cytochrome c in Guanidine HCl Probed by Femtosecond Vibrational Spectroscopy

Kim, Jooyoung,Park, Jaeheung,Lee, Taegon,Pak, Youngshang,Lim, Manho American Chemical Society 2013 The journal of physical chemistry. B, Condensed ma Vol.117 No.17

<P>Femtosecond vibrational spectroscopy was used to probe the rebinding dynamics of CO to cytochrome c (Cytc) in 1.8 and 7 M guanidine HCl (GdnHCl) after photodeligation of the corresponding CO-bound protein in D<SUB>2</SUB>O buffer (pD = 7.4) at 283 K. Geminate rebinding (GR) dynamics of CO to the folded Cytc in 1.8 M GdnHCl (<I>n</I>Cytc) is similar to that to chemically modified cytochrome c (cCytc), suggesting that the overall conformations of <I>n</I>CytcCO and <I>c</I>CytcCO are similar. About 86% of the dissociated CO molecules were geminately rebound to <I>n</I>Cytc nonexponentially within 1 ns. The efficient GR of CO to the folded Cytc can be attributed to the organized protein matrix near the active site of <I>n</I>Cytc that provides an efficient trap for the diffusing CO ligand after photodissociation. Although the concentration of <I>n</I>Cytc did not affect its GR yield of CO, GR yield of CO to the unfolded Cytc in 7 M GdnHCl (<I>u</I>Cytc) increased from 5 to 30% as the protein concentration increased from 0.3 to 9 mM. Time-resolved spectra of the <SUP>13</SUP>CO dissociated from both 9 mM <I>n</I>Cytc<SUP>13</SUP>CO and 9 mM <I>u</I>Cytc<SUP>13</SUP>CO showed a growing band with a peak at 2090 cm<SUP>–1</SUP> on the picosecond time scale, which was assigned to <SUP>13</SUP>CO in D<SUB>2</SUB>O solvent. At 1 ns, the fraction of the CO band in the solvent was about 10% of the nascent photodeligated protein in <I>n</I>Cytc and more than 50% in the concentrated <I>u</I>Cytc. Whereas a small opening in the active site of <I>n</I>Cytc is responsible for the ultrafast escape of CO to solution in the folded protein, a large fraction of the CO escape to the solvent in <I>u</I>Cytc results from the denatured structure of the active site in the unfolded protein. The spectrum of the CO dissociated from the concentrated <I>u</I>CytcCO contained a band that decayed as efficiently as that for the folded protein, suggesting that some fraction of <I>u</I>CytcCO might form aggregates even in 7 M denaturant, such that the aggregate acts as an efficient trap for the diffusing CO after deligation. No hint of precipitate in the concentrated <I>u</I>CytcCO and protein refolding upon dilution of the GdnHCl indicate that the aggregate does not grow continuously but remains as a soluble oligomer. The delayed appearance of the solvated CO and the inefficient GR of CO in <I>u</I>CytcCO suggest that the monomeric unfolded CytcCO so loosely arranged that the protein matrix cannot trap CO efficiently but the bound CO is still buried within hydrophobic residues even under the harsh denaturation condition.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcbfk/2013/jpcbfk.2013.117.issue-17/jp401481q/production/images/medium/jp-2013-01481q_0009.gif'></P>

Unidirectional Photo-induced Charge Separation and Thermal Charge Recombination of Cofacially Aligned Donor-Acceptor System Probed by Ultrafast Visible-Pump/Mid-IR-Probe Spectroscopy

Kim, Hyeong-Mook,Park, Jaeheung,Noh, Hee Chang,Lim, Manho,Chung, Young Keun,Kang, Youn K. Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.2

A new ${\pi}$-stacked donor-acceptor (D-A) system, [Ru(1-([2,2'-bipyridine]-6-yl-methyl)-3-(2-cyclohexa-2',5'-diene-1,4-dionyl)-1H-imidazole)(2,2':6',2"-terpyridine)]$[PF_6]_2$ (ImQ_T), has been synthesized and characterized. Similar to its precedent, [Ru(6-(2-cyclohexa-2',5'-diene-1,4-dione)-2,2':6',2"-terpyridine)(2,2':6',2"-terpyridine)]$[PF_6]_2$ (TQ_T), this system has a cofacial alignment of terpyridine (tpy) ligand and quinonyl (Q) group, which facilitates an electron transfer through ${\pi}$-stacked manifold. Despite the presence of lowest-energy charge transfer transition from the Ru-based-HOMO-to-Q-based-LUMO (MQCT) predicted by theoretical calculations by using time-dependent density functional theory (TD-DFT), the experimental steady-state absorption spectrum does not exhibit such a band. The selective excitation to the Ru-based occupied orbitals-to-tpy-based virtual orbital MLCT state was thus possible, from which charge separation (CS) reaction occurred. The photo-induced CS and thermal charge recombination (CR) reactions were probed by using ultrafast visible-pump/mid-IR-probe (TrIR) spectroscopic method. Analysis of decay kinetics of Q and $Q^-$ state CO stretching modes as well as aromatic C=C stretching mode of tpy ligand gave time constants of <1 ps for CS, 1-3 ps for CR, and 10-20 ps for vibrational cooling processes. The electron transfer pathway was revealed to be Ru-tpy-Q rather than Ru-bpy-imidazol-Q.