N.M.R. studies of myelin basic protein. V. 1H N.M.R. of the peptides encephalitogenic in guinea pig

1981 ◽  
Vol 34 (7) ◽  
pp. 1373 ◽  
Author(s):  
SA Margetson ◽  
WJ Moore ◽  
WA Gibbons
Keyword(s):  
Myelin Basic Protein ◽  
Ring Current ◽  
Basic Protein ◽  
Chemical Shifts ◽  
C Terminus ◽  
Proton Resonances ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects ◽  
Peptide Data ◽  
Made In

The 1H n.m.r. spectra of the following peptides have been investigated: (1) the encephalitogenic H-Phe-Ser-Trp-Gly-Ala-Glu-Gly-Gln-Lys-OH comprising residues 114-122 of bovine myelin basic protein, (2) the corresponding -Arg-OH peptide of human basic protein, (3) the inactive peptide in which D-Ala5 replaces L-Ala5. Measurements were made in D2O solutions at 270 and 600 MHz over a range of temperatures, concentrations and pH. All the proton resonances have been assigned by comparisons with other peptide data, titration shifts, selective decoupling and nuclear Overhauser effects, and data on the (α,α- 2H2)Gly7 nonapeptide. Ring current shifts and their temperature dependence indicated that there is preferential stacking of the Phe and Trp rings, and also interactions between these rings and the Gln and Lys residues near the C-terminus of the peptide. These data suggest a reverse turn at the Gly4-Ala5 residues, a conformation that would be consistent with results from energy calculations and biological activity. The n.m.r. spectra of the L-Ala and D-Ala peptides differed in the temperature coefficients of certain chemical shifts, including particularly those subject to ring current effects. Data in dimethyl sulfoxide were limited by effects of aggregation, but definite conformation differences compared to aqueous solutions were indicated.

N.M.R. studies of myelin basic protein. VII. Concentration and temperature dependence of amide resonances of the guinea pig encephalitogen in dimethyl sulfoxide

1983 ◽  
Vol 36 (1) ◽  
pp. 33 ◽  
Author(s):  
H Sadikot ◽  
WJ Moore
Keyword(s):  
Magnetic Resonance ◽  
Myelin Basic Protein ◽  
Dimethyl Sulfoxide ◽  
Proton Magnetic Resonance ◽  
Basic Protein ◽  
Chemical Shifts ◽  
Compact Structure ◽  
Temperature Coefficients ◽  
Reverse Turn ◽  
Nuclear Overhauser

The encephalitogenic peptide comprising residues 114-122 in human myelin basic protein, Phe-Ser-Trp-Gly-Ala-Glu-Gly-Gln-Arg, has been studied by proton magnetic resonance at 400 MHz in dimethyl sulfoxide solutions. Temperature coefficients of the chemical shifts of the amide resonances of Glu6, Gly7 and Arg9 have low values indicative of shielding from solvent. These data and nuclear Overhauser enhancements between protons widely separated in the primary structure suggest a compact structure for the peptide in dimethyl sulfoxide, probably associated with a reverse turn about the Gly4Ala5 residues. In freshly prepared solutions in the concentration range 0.20-5.0 mM, effects of intermolecular aggregation are not observed, but such aggregation may occur under other conditions.

scholarly journals Characterization of the structure and redox behaviour of cytochrome c3 from Desulfovibrio baculatus by 1H-nuclear-magnetic-resonance spectroscopy

1993 ◽  
Vol 294 (3) ◽  
pp. 899-908 ◽  
Author(s):  
I B Coutinho ◽  
D L Turner ◽  
J LeGall ◽  
A V Xavier
Keyword(s):  
Chemical Shifts ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Resonance Spectroscopy ◽  
Cytochrome C3 ◽  
X Ray ◽  
1H Nuclear Magnetic Resonance ◽  
Proton Resonances ◽  
Nuclear Overhauser

Complete assignment of the aromatic and haem proton resonances in the cytochromes c3 isolated from Desulfovibrio baculatus strains (Norway 4, DSM 1741) and (DSM 1743) was achieved using one- and two-dimensional 1H n.m.r. Nuclear Overhauser enhancements observed between haem and aromatic resonances and between resonances due to different haems, together with the ring-current contributions to the chemical shifts of haem resonances, support the argument that the haem core architecture is conserved in the various cytochromes c3, and that the X-ray structure of the D. baculatus cytochrome c3 is erroneous. The relative orientation of the haems for both cytochromes was determined directly from n.m.r. data. The n.m.r. structures have a resolution of approximately 0.25 nm and are found to be in close agreement with the X-ray structure from D. vulgaris cytochrome c3. The proton assignments were used to relate the highest potential to a specific haem in the three-dimensional structure by monitoring the chemical-shift variation of several haem resonances throughout redox titrations followed by 1H n.m.r. The haem with highest redox potential is not the same as that in other cytochromes c3.

Conformational and Structural characterization of carbohydrates and their interactions studied by NMR

2021 ◽  
Vol 28 ◽  
Author(s):  
Francisco Javier Cañada ◽  
Ángeles Canales ◽  
Pablo Valverde ◽  
Beatriz Fernández de Toro ◽  
Mónica Martínez-Orts ◽  
...  
Keyword(s):  
Structural Information ◽  
Theoretical Calculations ◽  
Chemical Shifts ◽  
Structural Complexity ◽  
Coupling Constants ◽  
Resonance Spectroscopy ◽  
Additional Information ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects

: Carbohydrates, either free or as glycans conjugated with other biomolecules, participate in many essential biological processes. Their apparent simplicity in terms of chemical functionality hides an extraordinary diversity and structural complexity. Deeply deciphering at the atomic level their structures is essential to understand their biological function and activities, but it is still a challenging task in need of complementary approaches and no generalized procedures are available to address the study of such complex, natural glycans. The versatility of Nuclear Magnetic Resonance spectroscopy (NMR) often makes it the preferred choice to study glycans and carbohydrates in solution media. The most basic NMR parameters, namely chemical shifts, coupling constants and nuclear Overhauser effects, allow defining short or repetitive chain sequences and characterize their structures and local geometries either in the free state or when interacting with other biomolecules, rendering additional information on the molecular recognition processes. The increased accessibility to carbohydrate molecules extensively or selectively labeled with 13C boosts the resolution and detail that analyzed glycan structures can reach. In turn, structural information derived from NMR, complemented with molecular modeling and theoretical calculations can also provide dynamic information on the conformational flexibility of carbohydrate structures. Furthermore, using partially oriented media or paramagnetic perturbations, it has been possible to introduce additional long-range observables rendering structural information on longer and branched glycan chains. In this review, we provide examples of these studies and an overview of the recent and most relevant NMR applications in the glycobiology field.

scholarly journals A combined NMR, MD and DFT conformational analysis of 9-O-acetyl sialic acid-containing GM3 ganglioside glycan and its 9-N-acetyl mimic

Glycobiology ◽  
2020 ◽  
Vol 30 (10) ◽  
pp. 787-801 ◽  
Author(s):  
Wanqing Li ◽  
Marcos D Battistel ◽  
Hannah Reeves ◽  
Lisa Oh ◽  
Hai Yu ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Density Functional ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Functional Theory ◽  
Acetylneuraminic Acid ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects ◽  
Intramolecular Hydrogen

Abstract O-Acetylation of carbohydrates such as sialic acids is common in nature, but its role is not clearly understood due to the lability of O-acetyl groups. We demonstrated previously that 9-acetamido-9-deoxy-N-acetylneuraminic acid (Neu5Ac9NAc) is a chemically and biologically stable mimic of the 9-O-acetyl-N-acetylneuraminic acid (Neu5,9Ac2) of the corresponding sialoglycans. Here, a systematic nuclear magnetic resonance (NMR) spectroscopic and molecular dynamics (MD) simulation study was undertaken for Neu5,9Ac2-containing GM3 ganglioside glycan (GM3-glycan) and its Neu5Ac9NAc analog. GM3-glycan with Neu5Ac as the non-O-acetyl form of Neu5,9Ac2 was used as a control. Complete 1H and 13C NMR chemical shift assignments, three-bond 1H-13C trans-glycosidic coupling constants (3JCH), accurate 1H-1H coupling constants (3JHH), nuclear Overhauser effects and hydrogen bonding detection were carried out. Results show that structural modification (O- or N-acetylation) on the C-9 of Neu5Ac in GM3 glycan does not cause significant conformational changes on either its glycosidic dihedral angles or its secondary structure. All structural differences are confined to the Neu5Ac glycerol chain, and minor temperature-dependent changes are seen in the aglycone portion. We also used Density Functional Theory (DFT) quantum mechanical calculations to improve currently used 3JHH Karplus relations. Furthermore, OH chemical shifts were assigned at −10°C and no evidence of an intramolecular hydrogen bond was observed. The results provide additional evidence regarding structural similarities between sialosides containing 9-N-acetylated and 9-O-acetylated Neu5Ac and support the opportunity of using 9-N-acetylated Neu5Ac as a stable mimic to study the biochemical role of 9-O-acetylated Neu5Ac.

N.M.R. studies on myelin basic protein. II. 1H N.M.R. studies of the protein and constituent peptides in aqueous solutions

1978 ◽  
Vol 31 (11) ◽  
pp. 2387 ◽  
Author(s):  
LAT Littlemore
Keyword(s):  
Chemical Shift ◽  
Myelin Basic Protein ◽  
Cathepsin D ◽  
Ring Current ◽  
Basic Protein ◽  
Tertiary Structure ◽  
Pulse Sequence ◽  
Chemical Shift Assignments ◽  
Peptide Fragment ◽  
Line Widths

1H N.M.R. spectra (270 MHz) of myelin basic protein (MBP) at pD 3.7 in D2O were obtained as a function of concentration and compared with computed spectra. Reduced line widths obtained for 0.5-mM samples and use of the convolution difference technique enabled detection of chemical shift heterogeneities for histidine, tyrosine, methionine, threonine, and isoleucine residues in the protein; this is indicative of secondary/tertiary structure. Chemical shift assignments were confirmed by the use of the Carr-Purcell A pulse sequence and selective decoupling as well as by correlation of the MBP spectrum with that of its constituent cathepsin D digest peptides. The methyl resonance from the unique methylated arginine-107 was found, and its chemical shift compared to that of NG-monomethyl-L-arginine and the methylated arginine peak in the peptide fragment, residues 90-170. The absence of ring- current effects on the methyl chemical shift precludes conformations of MBP in which the methylarginine interacts with the phenylalanine pair at residues 89 and 90.

Myelin basic protein, oligoclonal bands, and IgG in cerebrospinal fluid as indicators of multiple sclerosis.

1981 ◽  
Vol 27 (12) ◽  
pp. 1974-1977 ◽  
Author(s):  
B Gerson ◽  
S R Cohen ◽  
I M Gerson ◽  
G H Guest
Keyword(s):  
Multiple Sclerosis ◽  
Cerebrospinal Fluid ◽  
Myelin Basic Protein ◽  
Basic Protein ◽  
Clinical Laboratory ◽  
Screening Tests ◽  
Oligoclonal Bands ◽  
Oligoclonal Band ◽  
Laboratory Procedures ◽  
Made In

Abstract There currently are three clinical laboratory procedures for use with cerebrospinal fluid that assist in the diagnosis of multiple sclerosis: measurement of myelin basic protein and IgG, and demonstration of an oligoclonal band. We compared characteristics of these procedures, using CSF samples from 166 patients identified as having (54 patients) or not having (112 patients) multiple sclerosis. We find that oligoclonal band demonstration is the most useful single test in helping to establish the presence of multiple sclerosis; IgG quantitation is the least helpful. Myelin basic protein should be quantitated for following the activity of multiple sclerosis; it may be applied only selectively in the context of screening. The incidence of false-positive results reinforces the view that the diagnosis of multiple sclerosis must be made in clinical context. These laboratory procedures are not suitable for use as screening tests.

A nuclear Overhauser effect difference study and a two-dimensional J proton magnetic resonance study of (6S)-prostaglandin I1

1981 ◽  
Vol 59 (10) ◽  
pp. 1449-1454 ◽  
Author(s):  
George Kotovych ◽  
Gerdy H. M. Aarts ◽  
Tom T. Nakashima
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Nuclear Overhauser Effect ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Two Dimensional ◽  
Overhauser Effect ◽  
Effect Difference ◽  
Proton Resonances ◽  
Nuclear Overhauser

High-field nuclear Overhauser effect difference measurements allowed the assignment of the proton resonances for (6S)-prostaglandin I1 in phosphate buffer solutions. The two-dimensional J proton magnetic resonance experiments complemented these studies, as they also allowed the structure of several multiplets to be obtained when these multiplets are hidden by nearby resonances in a normal spectrum. The chemical shifts and coupling constants are compared with the data obtained previously for (6R)-prostaglandin I1.

scholarly journals Studies of the conformation of bilirubin and its dimethyl ester in dimethyl sulphoxide solutions by nuclear magnetic resonance

1982 ◽  
Vol 201 (3) ◽  
pp. 605-613 ◽  
Author(s):  
D Kaplan ◽  
G Navon
Keyword(s):  
Hydrogen Bonding ◽  
Chemical Shifts ◽  
Dimethyl Ester ◽  
Relaxation Times ◽  
Dimethyl Sulphoxide ◽  
13C Relaxation Times ◽  
Solvent Molecules ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects ◽  
13C Relaxation

The conformation of bilirubin and its dimethyl ester in dimethyl sulphoxide (DMSO) was investigated by n.m.r. spectroscopy. The chemical shifts of the pyrrole NH and Lactam protons of bilirubin and its dimethyl ester in DMSO indicate a strong interaction with the solvent. Inter-proton distances were calculated from nuclear Overhauser effects (NOE), selective and non-selective relaxation times (T1) and rotational correlation times taken from 13C relaxation times. The interproton distances indicate that the conformation of the skeleton of bilirubin and its dimethyl ester in DMSO is similar to that of bilirubin and mesobilirubin in the crystalline state and in chloroform solutions, except for a possible slight twist of the pyrrolenone rings about the methine bonds, which may be a consequence of solvation of the NH groups by DMSO. Unlike in chloroform solutions, no direct hydrogen-bonding occurs between the carboxylic acid and the lactam groups of bilirubin in DMSO, as shown by the absence of an NOE between these groups. The fast exchange of the pyrrole NH protons with 2H shows that no hydrogen-bonding occurs between these protons and the propionic residues, in line with their solvation by DMSO. From the above results, and from the slowness of the internal motion of the propionic residues of bilirubin and its dimethyl ester, it is concluded that these residues are tied to the skeleton via bound solvent molecules.

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