解 説 脂質の相転移と結晶化 - netsu.org

1 Netsu Sokutei 41(3), 104-112 (2014).. a . a .. 2014 5 22 2014 6 17 . Phase transition and Crystallization of Lipids Satoru Uenoa and Hiroshi Takahashib a Graduate School of Biosphere Sciences, Hiroshima University b Graduate School of Science and Technology, Gunma University (Received May 22, 2014; Accepted June 17, 2014). Lipids are the major substance in biological membrane. They also make an important role for industrial applications such as food, pharmaceutical and cosmetics. Here, we have reviewed the physical chemistry of lipids, especially, highlighted to triacylglycerols (TAGs) and phospholipids. In the TAGs part, the thermal and structural properties of PPP and POP, the typical TAGs, have been focused on.

2 The complicated polymorphism is present in TAGs. In order to determine polymorphs, time-resolved synchrotron radiation X-ray diffraction measurement and differential scanning calorimetry (DSC) under the same conditions, simultaneous or even though not simultaneous, is effective. As for phospholipid part, at first, the type of phospholipid and relationship between phospholipid and bio-membrane has been introduced. Secondly, crystal structure of phospholipid has also been introduced. Thirdly, the polymorphism and phase transitions of phospholipids under excess water, namely hydrated membrane state, have been highlighted. DSC data and its analysis, transition temperature, transition enthalpy and conformation entropy, have been explained and discussed.

3 Finally, an interesting topic about the relationship between phase transition and life activity has been introduced. Keywords: lipid, phospholipid, triacylglycerol, phase transition , polymorphism, crystallization.. Satoru Ueno E-mail: . Hiroshi Takahashi E-mail: 2014 The Japan Society of calorimetry and Thermal Analysis Netsu Sokutei 41 (3) 2014. 104.. 1.. 1, 2). wax .. 1, 2). Two ways of phase transformation. (a) enantiotropic, (b). monotropic. G: Gibbs free energy, T: temperature, A and B: phases , Tm(A) and Tm(B): Melting temperature of A and B. phase. Typical molecules of lipids. (a) n-octadecane, (b). n-octadecene (cis), (c) n-octadecene (trans), (d) stearic acid, (e) oleic acid, (f) triacylglycerol, (g) phosphatidylcholine, (h) sphingolipid.

4 MAG . TAG .. 1) Phase behavior of oleic acid. G: Gibbs free energy, T: temperature, , 1, 2 and polymorphs of oleic acid. 1 . 2 3 TAG . 3 .. 2. (e) . 6) . 1 , , , 4 7, 8) . 2 1. 9,10) . 2 1. H2O 6,10). 0 C 100 C 2 . MAG . enantiotropic monotropic . (a) pH .. 3). (a) A B 3 . G . (b) 1,2,4,5) . 1,2,4,5) . (b) B TAG . B I VI 6 . A 11,12) . Netsu Sokutei 41 (3) 2014. 105.. V .. V .. 11-13).. 3. DSC heating thermogram of tripalmitoyl glycerol (PPP). Heating rate is 5 C/min. TAG . 1, 2) (f) . R1, R2, R3 . R1, R2, R3 . TAG TAG . (b) TAG .. (melt-mediated transformation) 1,2,4,5) .. 3 . 16 . TAG . PPP C . C C X-ray diffraction patterns and corresponding subcell structure models of polymorphic forms of PPP.

5 H : hexagonal, C . O : orthorhombic perpendicular, T// : triclinic parallel.. C . C TAG. PPP ' X TAG POP 1,3-dipalmitoyl-2-oleoyl glycerol DSC . 1) SR-XRD 16) POP . Hexagonal(H) Orthorhombic(O . ) Triclinic(T//) . ' 14) subcell structure . O T // . TAG 1, 17-19) . , , , '2, '1, 2, 1 7 . ' ' . Table 1 .. 20) . TAG . DSC X SR-XRD 2 C min 1 2 C min 1 . SR-XRD (a) DSC C. DSC . SR-XRD nm . SR-XRD . 2 C min 1 C . 15) C ( . Netsu Sokutei 41 (3) 2014. 106.. Polymorphic behavior of POP, (a) cooling at 2 C min-1 and heating at 2 C min-1 and (b) cooling at 2 C min-1 and heating at 1 C min-1. For both, A; DSC patterns and B; wide angle SR XRD patterns.

6 C . C . Table 1 Thermal and structural data for polymorphs of POP. C .. DSC (a) DSC . Enthalpy of . Melting Subcell short 1 C min-1 . polymorphs Point fusion : spacing ( ) ( (b)) . (T /K) Hf /kJmol-1 C . * (vs) C C. (s), (m), C. (s), (w) . (s), (s), 2 C min-1 (a) 1 C min-1. (s) (b) . (w), (s), (a) (b). '2 (m), (s), (w) . (w), (m), SR-XRD DSC . '1 . (m), (s). (vs), (m), . (m), (m), 2 C min-1. 2 (m), (w), (a) . (w), (w) . (vs), (m), . 1 (m), (m), (s), (m) .. 1 C min-1 ( (b)) . * : Enthalpy of melt crystallization was measured on . vs : very strong, s : strong, m : medium, w : weak.. Netsu Sokutei 41 (3) 2014. 107.. TAG PG .. , '2, '1.

7 16) (a) . (b) . 14 22 . 24 26 .. C min-1 16 . 18 . (e) . 16) . 6 . 4. 1 2 .. 23) .. (g) . 1 2 . 24) .. (h) . (g) 25) .. 2 1 2 . 3 .. 26).. 1 2 .. 2 .. 21) 2 .. PC 2 .. PE 22) 27) . pH 1 18 . pH 1 28) .. PC PE .. PS pH . PS . Netsu Sokutei 41 (3) 2014. 108.. ULV . 2 . 12 . DLPE 32) . 29) DLPE . DLPE MLV .. (a) -PE(DEPE) . DSC 38 63 . 38 L . L . PC 14 L . 2 . DMPC 30) L . DMPC . 4 . DMPC 4 DLPE L L 36. 4 kJ mol-1 . DMPC 2 DEPE L . L . 2 L . DMPC DLPE .. DMPC L .. DMPC DLPE . PC PE . PC. PE PE . 3) PC PE . 31) .. PC PE .. 1 . 2 .. 2 DSC curves of fully hydrated (a) dielaidoyl-PE (DEPE). and (b) dipalymitoyl-PC (DPPC) multilamellar vesicles.

8 These DSC data were obtained from heating scans. The inserts show schematic illustrations of phospholipid molecular assemblies in the different phases separated by the phase transitions , and mean packing shape of a phospholipid molecule (cylinder, left, and inverted cone, right). See text for the details. Netsu Sokutei 41 (3) 2014. 109.. 63 L 2 PC PE . HII . HII L . 2 .. 33) PC PE DSC . PE PC 38) 39,40) . L L PC P ' L PE L L . 2 PE .. 1 . (b) (a) PE L H . L H .. PE .. 1 .. HII HII .. HII .. HII . HII . 34) .. (b) -PC(DPPC) . MLV DSC . 35 .. PE . 2 . (orthorhombic) . L ' prime . PC . L ' P ' . ripple .. kJmol-1 . 35,36) . 37) .. 42 C.

9 32 kJ mol-1 DPPC . P ' L . PC . 100 C HII (a) Dependence of the transition temperature on the chain length of saturated symmetric PC (P ' L phase transition , PC . closed circles ) and saturated symmetric PE (L L phase PE . transition , open circles , and L HII phase transition , closed . triangles ). The curves are best-fitting parabolic lines. (b). PE . Dependence of the transition enthalpy values on the chain length of saturated symmetric PC (P ' L phase transition , closed triangles ) and saturated symmetric PE (L L phase . transition , open circles ) and dependence of the transition entropy values on the chain length of saturated symmetric PC.

10 (P ' L phase transition , closed circles ) and saturated symmetric PE (L L phase transition , open triangles ). The lines are best-fitting linear regression lines. Netsu Sokutei 41 (3) 2014. 110.. 100 C 1 . (a) 100 C L H . PE . PE . n- 43) .. PC PE . PE L L . L . L . L . 2 .. HII .. PC . kJ mol-1 K-1 n-1 PE kJ mol-1 K-1 n-1 (a) . n L L L HII . 2 . 1 CH2 . PC kJmol-1K-1 PE kJ mol-1 K-1 (a) PE . PC Heimburg PE L L . Thermal Biophyiscs of Membranes 41) L HII 44). 1 . kJ mol-1 K-1 . Heimburg .. BL-9C . BL-6A 2010G114 . 2010G656 .. 1) , , - . - 1 . , (2011). 120 2 2) D. M. Small, The Physical Chemistry of Lipids from Alkanes to Phospholipids- (Chap.