Deuterium nuclear magnetic resonance (NMR) quadrupole echo spectra of deuterated acyl chains and the glyceryl moiety of tripalmitin were found to depend on the crystal form. At 20°C, which is below melting points, line shapes indicate that molecular motions in theβ form (triclinic subcell) are more restricted than inβ′ (orthorhombic) orα (hexagonal). Motional rates in excess of about 20 kHz are responsible for the line shapes. Spin‐lattice relaxation, sensitive to motional frequencies in the tens of megahertz range, is much faster for methyl (CD2) groups inα orβ′ than inβ, indicating that fast motions are also governed by crystal form. General theoretical considerations suggest that motion of methylene groups is dynamically heterogeneous and that motion of methyl (CD3) groups may be averaged by motions other than rotation about the terminal C‐C bond. The isothermal solid‐state transition fromα toβ, induced by increasing the temperature to 35°C, was accompanied by NMR lineshape changes consistent with immobilization. The reversible transition ofα to “sub‐α” upon cooling, accompanied by orthorhombic‐like Bragg spacings and other changes in the X‐ray pattern and by corresponding changes in the infrared spectrum, also produced a marked restriction in NMR‐detected mobility of the kind seen inβ′ relative toα. The advantages of2H NMR for studies of motions and transitions in solid glycerides are discussed.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIdentification of the Musty Component From an Off-Odor Packaging FilmRobert J. McGorrin, Thomas R. Pofahl, and William R. CroasmunCite this: Anal. Chem. 1987, 59, 18, 1109A–1112APublication Date (Print):September 15, 1987Publication History Published online30 May 2012Published inissue 15 September 1987https://doi.org/10.1021/ac00145a749RIGHTS & PERMISSIONSArticle Views81Altmetric-Citations20LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (3 MB) Get e-Alerts Get e-Alerts

Bilayer membranes containing distearoylphosphatidylcholine and chlorophyll a have been investigated via 1H- and 31P-NMR. Measurements as a function of temperature and composition support the basic interpretation of the phase diagram for this mixed bilayer system advanced in the preceding report. The 31P-NMR spectrum of mixed vesicles above the solidus temperature of the phase diagram shows a single resonance, but below the solidus two peaks are observed. Observation of two distinct 31P resonances from the phospholipid at 46°C conclusively demonstrates that phase separation occurs at temperatures below the solidus. Observation of a 5.8 ppm upfield shift for one of the 31P resonances at low temperature provides strong evidence for an interaction between the phospholipid headgroup and chlorophyll a in one of the low-temperature phases. This conclusion is supported by the observation of increased 1H linewidths for the lipid and a longer 1H T1 for the choline N-methyl resonance of the lipid below the solidus temperature, indicating that headgroups of lipid molecules in at least one of the phases are motionally restricted. The observation of an interaction between chlorophyll a and lipid molecules in a bilayer membrane lends considerable support to the idea that chlorophyll molecules in the chloroplast antenna are physically separated from each other by strongly coordinating lipid molecules.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNMR determination of site-specific deuterium isotope effectsDavid M. Grant, Janet Curtis, William R. Croasmun, Don K. Dalling, Felix W. Wehrli, and Suzanne WehrliCite this: J. Am. Chem. Soc. 1982, 104, 16, 4492–4494Publication Date (Print):August 1, 1982Publication History Published online1 May 2002Published inissue 1 August 1982https://pubs.acs.org/doi/10.1021/ja00380a033https://doi.org/10.1021/ja00380a033research-articleACS PublicationsRequest reuse permissionsArticle Views110Altmetric-Citations20LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Chemischer InformationsdienstVolume 13, Issue 45 Physical Organic Chemistry ChemInform Abstract: NMR DETERMINATION OF SITE-SPECIFIC DEUTERIUM ISOTOPE EFFECTS D. M. GRANT, Search for more papers by this authorJ. CURTIS, Search for more papers by this authorW. R. CROASMUN, Search for more papers by this authorD. K. DALLING, Search for more papers by this authorF. W. WEHRLI, Search for more papers by this authorS. WEHRLI, Search for more papers by this author D. M. GRANT, Search for more papers by this authorJ. CURTIS, Search for more papers by this authorW. R. CROASMUN, Search for more papers by this authorD. K. DALLING, Search for more papers by this authorF. W. WEHRLI, Search for more papers by this authorS. WEHRLI, Search for more papers by this author First published: November 9, 1982 https://doi.org/10.1002/chin.198245053AboutPDF 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 onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume13, Issue45November 9, 1982 RelatedInformation

The 13C-NMR spectrum at 90.5 MHz has been obtained for the photosynthetic thylakoid membrane of spinach. Specific lipid and chlorophyll resonances can be assigned in the high resolution spectrum, although protein resonances are not observed. It can be estimated from resonance intensities that at least 30% of the plant chlorophyll contributes to the high resolution 13C spectrum with the remainder broadened by incomplete motional averaging. The resonance linewidths of the observed chlorophyll phytol chains are approximately the same as those of the lipid hydrocarbon chains, indicating a similar motional state and suggesting that this particular pool of chlorophyll is lipid-bound or at most only loosely associated with proteins.