Detail of "4537-78-4"

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Calorimetric and spectroscopic studies of the thermotropic phase behavior of the n-saturated 1,2-diacylphosphatidylglycerols

Calorimetric and spectroscopic studies of the thermotropic phase behavior of the n-saturated 1,2-diacylphosphatidylglycerols. Zhang, Yuan-Peng; Lewis, Ruthven N. A. H.; McElhaney, Ronald N. ( Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Can.).In this study， 4537-77-3 and 4537-78-4 are also used. Biophysical Journal, 72(2, Pt. 1), 779-793 (English) 1997 Biophysical Society. CODEN: BIOJAU. ISSN: 0006-3495. DOCUMENT TYPE: Journal CA Section: 6 (General Biochemistry) The polymorphic phase behavior of a homologous series of n-satd. 1,2-diacyl phosphatidylglycerols (PGs) was studied by differential scanning calorimetry and Fourier transform IR and 31P-NMR spectroscopy. When dispersed in aq. media under physiol. relevant conditions, these compds. exhibit two thermotropic phase transitions that are structurally equiv. to the well-characterized pretransitions and gel/liq.-cryst. phase transitions exhibited by bilayers of the corresponding 1,2-diacyl phosphatidylcholines. Furthermore, when incubated at low temps., their gel phases spontaneously transform into one or more solid-like phases that appear to be highly ordered, quasicryst. bilayers that are probably partially dehydrated. The quasicryst. structures, which form upon short-term, low-temp. annealing of these lipids, are meta-stable with respect to more stable structures, to which they eventually transform upon prolonged low-temp. incubation. The rates of formation of the quasicryst. phases of the PGs generally tend to decrease as hydrocarbon chain length increases, and PGs whose hydrocarbon chains contain an odd no. of carbon atoms tend to be slower than those of neighboring even-numbered homologs. The calorimetric data also indicate that the quasicryst. phases of these compds. become progressively less stable relative to both their gel and liq.-cryst. phases as the length of the hydrocarbon chain increases and that they decomp. either to the liq.-cryst. phase (short- and medium-chain compds.) or to the normal gel phase (long-chain compds.) upon heating. The spectroscopic data indicate that although there is odd-even alternation in the structures of the quasicryst. phases formed upon short-term low-temp. incubation of these compds., the structural features of the stable quasicryst. phases eventually formed are all similar. Furthermore, the degree of hydration and the nature of hydrogen bonding interactions in the headgroup and interfacial regions of these PG bilayers differ significantly from that obsd. in all other phospholipid bilayers studied so far. We suggest that many of the properties of PG bilayers can be rationalized by postulating that the glycerol moiety of the polar headgroup is directly involved in shielding the neg. charges at the surface of the bilayer by means of hydration-like hydrogen bonding interactions with the phosphate moiety. .

Effects of distearoylphosphatidylglycerol and lysozyme on the structure of the monoolein-water cubic phase: X-ray diffraction and Raman scattering studies

Effects of distearoylphosphatidylglycerol and lysozyme on the structure of the monoolein-water cubic phase: X-ray diffraction and Raman scattering studies. Razumas, Valdemaras; Talaikyte, Zita; Barauskas, Justas; Larsson, K.are; Miezis, Yvonne; Nylander, Tommy (Department of Bioelectrochemistry, Institute of Biochemistry, Mokslininku 12, LT-2600, Vilnius, Lithuania). Chemistry and Physics of Lipids, 84(2), 123-138 (English) 1996 Elsevier.Chemicals with cas numbers 9001-63-2 and 4537-78-4 also play role. CODEN: CPLIA4. ISSN: 0009-3084. DOCUMENT TYPE: Journal CA Section: 6 (General Biochemistry) X-ray diffraction and Raman scattering spectroscopy have been used to study phase transitions and changes in mol. organization of the cubic Pn3m monoolein (MO)-H2O phase upon introducing low amts. of distearoylphosphatidylglycerol (DSPG) and lysozyme (LSZ). X-ray diffraction measurements indicated a phase transition Pn3m-Im3m brought about by DSPG and LSZ, however DSPG also induced formation of the lamellar phase. Raman spectra have demonstrated that incorporation of DSPG into the lipid bilayer decreases the mobility of acyl chains and increases the no. of hydrogen-bonded C:O groups of MO. LSZ exerts identical effect on the latter parameter, while no effect on the state of acyl chains order was obsd. This result and differential scanning calorimetric measurements indicate that LSZ is located in the water channel system of the cubic phase. The results are discussed on a basis of an infinite periodical lipid bilayer structure and lipid packing parameter concepts. .