Two-dimensional Double Quantum Research Articles

Two-dimensional multiple-quantum NMR spectroscopy of isolated half-integer spin systems. II. 35Cl examples

Two-dimensional double-quantum (2D2Q) 35Cl NMR spectra of systems exhibiting electric quadrupolar effects have been obtained. Single-crystal type spectra ( type a) result from magnetic field-oriented lyotropic liquid crystalline samples containing Cl − ions. Inhomogeneous powder patterns ( type b) result from unoriented lyotropic liquid crystalline samples. A homogeneous biexponentially relaxed spectrum ( type c) results from a sufficiently concentrated solution of a macromolecule in Cl −containing medium. The theory of the 2D2Q experiment on isolated spin-2 systems producing type a spectra has been elaborated. The effects of variation of the flip angle of the read pulse and offset of the excitation frequency have been derived. Experimental manifestations of these effects have been recorded. The recovery of the spectrum of an oriented lyotropic liquid crystalline sample after a sample rotation in the spectrometer magnetic field provides an example of transient, partial NMR invisibility in the one-dimensional single-quantum 35Cl NMR spectrum.

Analysis of the aromatic 1H-NMR spectrum of the kringle 5 domain from human plasminogen. Evidence for a conserved kringle fold.

A kringle 5 domain fragment from human plasminogen has been investigated by 1H-NMR spectroscopy at 300 MHz and 620 MHz. The study focuses on the kringle 5 aromatic spectrum as aromatic side chains appear to mediate the binding of benzamidine. Spin-echo experiments and acid/base-titration studies in conjunction with two-dimensional double-quantum and chemical-shift-correlated spectroscopies were used to identify individual spin systems. Sequence-specific assignments of aromatic resonances are derived from direct comparison of the kringle 5 spectrum with spectra of the homologous kringle 1 and kringle 4 domains of plasminogen. As previously observed for kringles 1 and 4, the pattern we detect for Tyr9 in kringle 5 reflects a slow conformational exchange between two states in equilibrium, one in which the Tyr9 ring is freely mobile and one in which its flip dynamics are constrained. Proton Overhauser experiments in 1H2O and in 2H2O have been used to probe aromatic ring interactions and to identify residues which are part of the hydrophobic core centered at the Leu46 side chain. Overall, the data indicate a strong structural homology among the three plasminogen kringles.

Application of double quantum filtered phase sensitive two-dimensional NMR spectroscopy: Chemistry of pentamethylcyclopentadienyl- and indenyl-platinum complexes

Two-dimensional double quantum filtered phase sensitive (DQPH)COSY NMR spectroscopy has been used to aid characterization of new η-pentamethylcyclopentadienyl- and η-indenyl-platinum complexes. The syntheses of the first mononuclear η-pentamethylcyclopentadienylplatinum complexes are reported.

NMR of a synthetic peptide spanning the triphosphate binding site of adenosine 5'-triphosphate in actin.

The amino acid residues 114-118 in actin were found to be implicated strongly in the binding of nucleotide, and as would be expected for such an important binding site, they are located in a completely conserved region of the actin sequence. A 19-residue peptide with the actin sequence 106-124 was synthesized in order to span the putative triphosphate binding site. Proton NMR spectra of the actin peptide 114-118 in the presence and absence of ATP indicated that Arg-116 and Lys-118 are particularly involved in binding ATP. A strong binding of ATP to the peptide 106-124 also was measured. Tripolyphosphate bound to the peptide 106-124 somewhat more weakly than ATP. Binding involved residues 115-118 and 121-124, indicating the presence of a reverse turn between these segments. Proton resonances were assigned by using two-dimensional double quantum correlated spectroscopy, one-dimensional spin decoupling techniques, one-dimensional nuclear Overhauser enhancement difference spectroscopy, and pH titration. The alpha CH resonances of Ala-3 and Asn-6 are markedly shifted downfield with respect to values in small unstructured peptides due to their close proximity to the side chains of Pro-4 and Pro-7, respectively. Several other resonances display chemical shifts which are indicative of a structured environment. Assignment of the amide proton resonances in H2O and measurements of the coupling constant 3JHNCH and the chemical shifts of the amide protons reveal that much of the synthetic peptide, particularly the backbone, exhibits a highly structured environment and represents a good model for the triphosphate binding site in actin.

ChemInform Abstract: TWO‐DIMENSIONAL NMR STUDIES OF MARINE NATURAL PRODUCTS. 2. UTILIZATION OF TWO‐DIMENSIONAL PROTON DOUBLE QUANTUM COHERENCE NMR SPECTROSCOPY IN NATURAL PRODUCTS STRUCTURE ELUCIDATION ON ‐ DETERMINATION OF LONG‐RANGE COUPLINGS IN PLUMERICIN

Chemischer InformationsdienstVolume 16, Issue 43 Physical Organic Chemistry ChemInform Abstract: TWO-DIMENSIONAL NMR STUDIES OF MARINE NATURAL PRODUCTS. 2. UTILIZATION OF TWO-DIMENSIONAL PROTON DOUBLE QUANTUM COHERENCE NMR SPECTROSCOPY IN NATURAL PRODUCTS STRUCTURE ELUCIDATION ON - DETERMINATION OF LONG-RANGE COUPLINGS IN PLUMERICIN G. E. MARTIN, G. E. MARTINSearch for more papers by this authorR. SANDUJA, R. SANDUJASearch for more papers by this authorM. ALAM, M. ALAMSearch for more papers by this author G. E. MARTIN, G. E. MARTINSearch for more papers by this authorR. SANDUJA, R. SANDUJASearch for more papers by this authorM. ALAM, M. ALAMSearch for more papers by this author First published: October 29, 1985 https://doi.org/10.1002/chin.198543058AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume16, Issue43October 29, 1985 RelatedInformation

Correlation of aliphatic proton chemical shifts in proteins using two-dimensional double-quantum correlated spectroscopy

Double-quantum coherences have been used in several ways to aid the interpretation of ‘H NMR spectra of proteins (1-3). For example, double-quantum filtration has been employed in COSY experiments to reduce the intensity of diagonal peaks (2). The detection of remote connectivities in two-dimensional double-quantum spectra has been used to overcome the problems of overlap in the identification of coupled spin systems (3). Recently we discussed the application of two-dimensional dosblequantum spectroscopy to the identification of spin systems of the aromatic amino acids in the ‘H NMR spectra of proteins (I). In this communication we sh,ow that doublequantum coherences are also useful for the identification of resonances arising from methyl groups. In the study of the aromatic amino acids double-quantum coherence was found to be created with good sensitivity when preparation periods of 7 = 15 ms ( l/W) and 7 = 30 ms (1/4J) were used in the INADEQUATE pulse sequence (I, 4). The coupling between the methyl protons of alanine, threonine, leucine, valine, and isoleucine and the adjacent methylene or methyne protons is approximately 7 Hz, similar in magnitude to that between ring protons of aromatic amino acids (approximately 8 Hz) (5). Therefore, with a preparation period, T, of either 15 or 30 ms double-quantum coherence should be created with quite good sensitivity for these aliphatic amino acids. In all the experiments reported here a detection pulse of 3?r/4 was used to suppress correlations from remote spins and to suppress peaks which could arise from multiple-quantum coherence creation within methyl groups (6, 7). Both of these types of peaks were previously shown to occur in doublequ.antum spectra of alanine and threonine when a a/2 detection pulse was used (6). The double-quantum spectra of alanine, threonine, and valine obtained with a T value of 30 ms and of isoleucine obtained with 7 values of 15 and 30 ms are shown in Figs. 1 and 2. The doublequantum spectrum of alanine, threonine, and valine obtained with a r value of 15 ms is very similar to the r = 30 ms spectrum and provides no additional information. The double-quantum spectrum of leucine is qualitatively similar to that of valine and is not reproduced here. Several interesting features emerge from an examination of the double-quantum spectra. All the peaks observed correspond to direct connectivities. The most intense peaks in spectra obtained with a 7 value of 30 ms arise from the doublet methyl

Assignment of aromatic spin systems in the 1H nuclear magnetic resonance spectrum of adenylate kinase

A combination of selective spin decoupling, two-dimensional double quantum spectroscopy, correlated spectroscopy (COSY), and pH titration experiments brought about the assignment of all tyrosyl spin systems and completed the assignment of the histidyl spin systems in porcine adenylate kinase. In the detection of the tyrosyl spin systems it proved to be advantageous to resort to the COSY method rather than to two-dimensional double quantum spectroscopy. In the titration experiments, His189 revealed a second apparent p K value at pH 8.3, which is explained by deprotonation of the adjacent residue Cysl87. None of the seven tyrosyl side-chains shows any evidence for deprotonation up to the point of denaturation of the protein, which took place around pH 10.

ChemInform Abstract: TWO‐DIMENSIONAL DOUBLE‐QUANTUM COHERENCE ECHO CORRELATED SPECTROSCOPY IN PROTON NMR

Chemischer InformationsdienstVolume 15, Issue 45 Physical Organic Chemistry ChemInform Abstract: TWO-DIMENSIONAL DOUBLE-QUANTUM COHERENCE ECHO CORRELATED SPECTROSCOPY IN PROTON NMR M. IKURA, M. IKURASearch for more papers by this authorK. HIKICHI, K. HIKICHISearch for more papers by this author M. IKURA, M. IKURASearch for more papers by this authorK. HIKICHI, K. HIKICHISearch for more papers by this author First published: November 6, 1984 https://doi.org/10.1002/chin.198445051AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume15, Issue45November 6, 1984 RelatedInformation

Combined use of COSY and double quantum two-dimensional NMR spectroscopy for elucidation of spin systems in polymyxin B

Two-dimensional single quantum correlation NMR spectroscopy (COSY) and two-dimensional double quantum NMR spectroscopy (2QT) are used to study spin systems in the 1H NMR spectrum of polymyxin B. Because of different frequency relationships, the two types of two-dimensional NMR experiments are found to be highly complementary. This is demonstrated by combined use of COSY and 2QT spectroscopy to obtain a complete analysis of the complicated spectral overlap which occurs in the 1H NMR spectrum of polymyxin B.

Practical aspects of carbon-13 double quantum NMR

We want to address an erroneous view that has recently been advanced on 13C double quantum NMR. A recent publication (I) introduced a modified version (I) of the original double quantum NMR experiments; this new version claims to offer an attractive increase in sensitivity by a factor of three, or a decrease in the size of the required data matrix by a factor of four. To avoid disappointment among spectroscopists we wish to make it clear that this modified version offers no gain in sensitivity whatsoever in comparison with the other double quantum experiments (2-6), provided they are properly optimized. It is shown here that the sensitivity of this modified experiment can be even slightly lower. The claim of a reduction of the size of the required data matrix is also shown to be incorrect. In the original two-dimensional double quantum “C experiments, the acquisition time t2 starts immediately after the final “read pulse” (Fig. 1), and the time during which the double quantum coherence evolves is labeled ti. The detected 13C-13C satellites (7) are modulated in amplitude as a function of tl with the double quantum frequencies (2). In the quadrature-Fi-detection version of this experiment (3), results are combined with those of a second experiment which contains a composite 45: pulse (8) in the evolution period. This allows the sign of the modulation frequency to be determined, which simplifies the interpretation of the results. A simpler and more sensitive alternative to obtain quadrature F, detection has been proposed more recently (6); an increase of the flip angle of the final “read pulse” to 135” provides directly satellite signals which are modulated in phase as a function oft,. In either case, data acquisition is started after the final read pulse and the coherence transfer echo (9) is detected (4, 6). The time domain signal of a carbon A, directly coupled to carbon X, is then given by sA(tl, t2) = c exp[-i(nA + &)t,] exp[i& + d&2]

Two-dimensional double quantum 1H NMR spectroscopy of proteins

Two-dimensional double quantum 1H NMR spectra are recorded for a protein. The application of this technique to macromolecules is shown not to be impeded by the long preparation pulse sequence essential for this experiment. The identification of spin systems by analysis of the double quantum spectrum is illustrated. Since double quantum spectra do not contain diagonal peaks, connectivities between almost degenerate signals can be detected. By analysis of remote connectivities (i) it can be established whether amide and β-protons belong to the same spin system or not, (ii) degeneracy of β-proton chemical shifts can be demonstrated, and (iii) glycine amide protons can be distinguished from all others.