Measurement of Spin Relaxation in Complex Systems

Vold, Robert L.; Waugh, J. S.; Klein, Melvin P.; Phelps, Donald E.

doi:10.1063/1.1669699

Cited by 1,297 publications

(583 citation statements)

References 10 publications

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“…The change in temperature was always less or equal to 5 K. The samples were sealed in 5 mm NMR tubes. Longitudinal relaxation rates, 1/T 1 , were obtained by the inversion recovery method 34 and transverse relaxation rates, 1/T 2 , directly from the line widths.…”

Section: O Nmrmentioning

confidence: 99%

Water exchange rates of water-soluble manganese(iii) porphyrins of therapeutical potential

et al. 2010

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The activation parameters and the rate constants of the water-exchange reactions of Mn III TE-2-PyP 5+ (meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin) as cationic, Mn III TnHex-2-PyP 5+ (meso-tetrakis(N-n-hexylpyridinium-2-yl)porphyrin) as sterically shielded cationic, and Mn III TSPP 3-(meso-tetrakis(4-sulfonatophenyl)porphyrin) as anionic manganese(III) porphyrins were determined from the temperature dependence of 17 O NMR relaxation rates. The rate constants at 298 K were obtained as 4.12 ¥ 10 6 s -1 , 5.73 ¥ 10 6 s -1 , and 2.74 ¥ 10 7 s -1 , respectively. On the basis of the determined entropies of activation, an interchange-dissociative mechanism (I d ) was proposed for the cationic complexes (DS ‡ =~0 J mol -1 K -1 ) whereas a limiting dissociative mechanism (D) was proposed for Mn III TSPP 3-complex (DS ‡ = +79 J mol -1 K -1 ). A magnitude of the obtained water-exchange rate constants further confirms the suggested inner sphere electron transfer mechanism for the reactions of the two positively charged Mn(III) porphyrins with the various biologically important oxygen and nitrogen reactive species. Due to the high biological and clinical relevance of the reactions that occur at the metal site of the studied Mn(III) porphyrins, the determination of water exchange rates advanced our insight into their efficacy and mechanism of action, and in turn should impact their further development for both diagnostic (imaging) and therapeutic purposes.

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Section: O Nmrmentioning

confidence: 99%

Water exchange rates of water-soluble manganese(iii) porphyrins of therapeutical potential

et al. 2010

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“…The "N chemical shift reference was CH3N02, which was assigned a value of 380.23 ppm (Live et al, 1984). Two-dimensional sensitivity-enhanced pulse sequences (Cavanagh et al, 1991;Palmer et al, 1991;Skelton et al, 1993) were employed for the inversion-recovery (Vold et al, 1968), CPMG spin-echo (Meiboom & Gill, 1958), and steady-state NOE (Noggle & Shirmer, 1971) experiments to measure the spin-lattice relaxation rate constants @'), spin-spin relaxation rate constants (R2). and {'H}-"N steady-state NOES, respectively, of backbone and arginine side chain "NH groups in rCMTI-III and rCMTI-III*.…”

Section: Nmr Spectroscopymentioning

confidence: 99%

NMR studies of internal dynamics of serine proteinase protein inhibitors: Binding region mobilities of intact and reactive‐site hydrolyzed Cucurbita maxima trypsin inhibitor (CMTI)‐III of the squash family and comparison with those of counterparts of CMTI‐V of the potato I family

et al. 1998

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Serine proteinase protein inhibitors follow the standard mechanism of inhibition (Laskowski M Jr, Kato I, 1980, Annu Rev Biochem 49593‐626), whereby an enzyme‐catalyzed equilibrium between intact (I) and reactive‐site hydrolyzed inhibitor (I*) is reached. The hydrolysis constant, Khyd is defined as [I*]/[I]. Here, we explore the role of internal dynamics in the resynthesis of the scissile bond by comparing the internal mobility data of intact and cleaved inhibitors belonging to two different families. The inhibitors studied are recombinant Cucurbita maxima trypsin inhibitor III (rCMTI‐III; Mr 3 kDa) of the squash family and rCMTI‐V (Mr ∼ 7 kDa) of the potato I family. These two inhibitors have different binding loop‐scaffold interactions and different Khyd values—2.4 (CMTI‐III) and 9 (CMTI‐V)—at 25°C. The reactive‐site peptide bond (P1‐P'1) is that between Arg5 and Ile6 in CMTI‐III, and that between Lys44 and Asp45 in CMTI‐V. The order parameters (S2) of backbone NHs of uniformly 15N‐labeled rCMTI‐III and rCMTI‐III* were determined from measurements of 15N spin‐lattice and spin‐spin relaxation rates, and {1H}‐15N steady‐state heteronuclear Overhauser effects, using the model‐free formalism, and compared with the data reported previously for rCMTI‐V and rCMTI‐V*. The backbones of rCMTI‐III (〈S2〉 = 0.71) and rCMTI‐III* (〈S2) = 0.63) are more flexible than those of rCMTI‐V (〈S2〉 = 0.83) and rCMTI‐V* (〈S2) = 0.85). The binding loop residues, P4‐P1, in the two proteins show the following average order parameters: 0.57 (rCMTI‐III) and 0.44 (rCMTI‐III*); 0.70 (rCMTI‐V) and 0.40 (rCMTI‐V*). The P1′‐P4′ residues, on the other hand, are associated with (S2) values of 0.56 (rCMTI‐III) and 0.47 (rCMTI‐III*); and 0.73 (rCMTI‐V) and 0.83 (rCMTI‐V*). The newly formed C‐terminal (Pn residues) gains a smaller magnitude of flexibility in rCMTI‐III* due to the Cys3‐Cys20 crosslink. In contrast, the newly formed N‐terminal (Pn′ residues) becomes more flexible only in rCMTI‐III*, most likely due to lack of an interaction between the P1′ residue and the scaffold in rCMTI‐III. Thus, diminished flexibility gain of the Pn residues and, surprisingly, increased flexibility of the Pn′ residues seem to facilitate the resynthesis of the P1‐P1′ bond, leading to a lower Khyd value.

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“…NMR spin-relaxation experiments were performed using gradient-selected sensitivityen-hanced pulse sequences, as previously published (Kördel et al, 1992;Meiboom and Gill, 1958;Noggle and Shirmer, 1971;Vold et al, 1968) The transverse (R 2 ) relaxation rates of HP-RR e were obtained with total relaxation delays of 0.0 (× 2), 0.0172, 0.0345, 0.0517 (× 2), 0.0690, 0.0862, and 0.103 seconds. All relaxation spectra of HP-RR r were acquired with the 1 H carrier set coincident with the water resonance and 15 N frequency set to 116.5 ppm; spectral widths were 6,012.821 Hz and 1,470.588 Hz in the t 2 and t 1 dimension, with 2,048 and 200 complex points in each dimension, respectively.…”

Section: Nmr Experiments For Backbone Dynamicsmentioning

confidence: 99%

Backbone Dynamics of an Atypical Orphan Response Regulator Protein, Helicobacter pylori 1043

Jeong

Lee

et al. 2013

Molecules and Cells

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An atypical orphan response regulator protein, HP1043 (HP-RR) in Helicobacter pylori, is proven to be essential for cell growth and does not require the well known phosphorelay scheme. HP-RR was identified as a symmetric dimer with two functional domains, an N-terminal regulatory domain (HP-RR r ) and a C-terminal effector domain (HP-RR e ). HP-RR is a new class of response regulator, as a phosphorylation-independent regulator. Previously, we have presented a detailed three-dimensional structure of HP-RR using NMR spectroscopy and X-ray crystallography. In this study, in order to understand the functional importance of flexibilities in HP-RR r and HP-RR e , T 1 , T 2 , heteronuclear NOE experiments have been performed and backbone dynamics of HP-RR r and HP-RR e were investigated. HP-RR r is a symmetric dimer and the interface region, α4-β5-α5 of dimer, showed high rigidity (high S 2 values). Site of rearrangements associated with phosphorylation of HP-RR r (Ser 75 : R ex = 3.382, Ile 95 : R ex = 5.228) showed slow chemical exchanges. HP-RR e is composed of three α-helices flanked on two sides by anti-parallel β-sheets. Low order parameters as well as conformational exchanges in the centers of loop regions known as the DNA binding site and transcription site of HP-RR e suggested that flexibility of HP-RR e is essential for interaction with DNA. In conclusion, backbone dynamics information for HP-RR implies that structural flexibilities in HP-RR r are necessary for the phosphorylation site and the dynamic nature of HP-RR e is essential for the regulation of interaction between protein and DNA.

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Measurement of Spin Relaxation in Complex Systems

Cited by 1,297 publications

References 10 publications

Water exchange rates of water-soluble manganese(iii) porphyrins of therapeutical potential

Water exchange rates of water-soluble manganese(iii) porphyrins of therapeutical potential

NMR studies of internal dynamics of serine proteinase protein inhibitors: Binding region mobilities of intact and reactive‐site hydrolyzed Cucurbita maxima trypsin inhibitor (CMTI)‐III of the squash family and comparison with those of counterparts of CMTI‐V of the potato I family

Backbone Dynamics of an Atypical Orphan Response Regulator Protein, Helicobacter pylori 1043

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