Interaction Between Dipalmityl Phosphatidylcholine and Vitamin B2
Studied by Second Harmonic Spectroscopy and Brewster Angle
Microscopy
LIU Jiang-qing1, YU Chang-hui2, 3, GUO Yuan2, 3, LEI Sheng-bin1*, ZHANG Zhen2, 3*
1. Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, China
2. Beijing National Research Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
3. University of Chinese Academy of Sciences, Beijing 100049, China
Abstract：Langmuir monolayers formed by dipalmityl phosphatidylcholine (DPPC) molecules at the air/liquid interface are an important model system for studying the biomembranes, and their chiral structure and interaction with foreign substances have been the frontiers of related fields. Vitamin B2 (VB2) is an important medicine for treating lipid deposition diseases caused by metabolic disorders. The molecular mechanism of the interaction between VB2 and phospholipids is the key to understanding the function of VB2. In this report, the interaction between VB2 and DPPC at the air/water interface was studied using second-harmonic generation linear dichroism (SHG-LD), Langmuir membrane balance and Brewster Angle Microscopy (BAM). The compression isotherm shows that the surface pressure in the liquid expansion phase/liquid condensed phase (LE/LC) of L-DPPC and D-DPPC at the water interface is almost unchanged, while the film pressure region in the co-existing phase of race-DPPC is slightly shortened. The LE /LC coexistence phase of race-DPPC disappears at the interface of the VB2 aqueous solution. In addition, the elastic modulus studies show that the VB2 molecule can increase the elastic modulus of L-DPPC monolayers, but reduce the elastic modulus of D-DPPC and race-DPPC monolayers. SHG-LD results showed that the Degree of Chiral Excess (DCE) of L-DPPC at the interface between VB2 and water was unchanged at the surface pressure of 13 mN·m-1, and the DCE of D-DPPC at the interface between VB2 and water was reversed. The DCE value of race-DPPC does not change with the change of subphase. Under the same surface pressure, BAM observed that the interaction of L-DPPC and D-DPPC to assemble into homochiral microdomains with different arm curvature directions at the pure water interface, and VB2 could induced the increase of D-DPPC microdomains by 1 to 2 times. Meanwhile, VB2 induced the extension of approximately circular microdomains on race-DPPC monolayer and the growth of three curvature arms, which could be explained as VB2 reducing the energy of non-monolayer chiral interactions and resulting in chiral phase separation. VB2 also induced changes in the chiral structure of race-DPPC monolayers. This study is of great significance for understanding the regulation of VB2 on the macrostructure and biological function of the phospholipid membrane.
[1] Moon R J, Martini A, Nairn J, et al. Chemical Society Reviews, 2011, 40: 3941.
[2] Stefaniu C, Brezesinski G, Moehwald H. Advances in Colloid and Interface Science, 2014, 208: 197.
[3] Ou-yang W, Yamamoto T, Aida T, et al. Thin Solid Films, 2008, 516：2649.
[4] Wu Y, Han J Z, Wang Y Y, et al. Journal of International Medical Research, 2020, 48：8.
[5] Verbiest T, Kauranen M, Maki J J, et al. The Journal of Chemical Physics, 1995, 103: 8296.
[6] Hénon S, Meunier J. Review of Scientific Instruments, 1991, 62: 936.
[7] Fanani M L, Hartel S, Oliveira R G, et al. Biophysical Journal, 2002, 83: 3416.
[8] Dong B, Bai R, Zheng W, et al. The Journal of Physical Chemistry C, 2019, 123: 11798.
[9] Nieuwkerk A C, van Kan E J M, Kimkes P, et al. Langmuir, 1998, 14: 6448.
[10] Nassoy P, Goldmann M, Bouloussa O, et al. Physical Review Letters, 1995, 75: 457.
[11] Hossain M M, Suzuki T, Kato T. Langmuir, 2000, 16：9109.
[12] Weidemann G，Vollhardt D. Biophysical Journal, 1996, 70：2758.
[13] Behroozi F. Langmuir, 1996, 12: 2289.
[14] Khattari Z, Maghrabi M, Al-Abdullah T. Phase Transitions, 2015, 88：668.
[15] Lin L, Liu A，Guo Y. Journal of Physical Chemistry C, 2012, 116: 14863.
[16] Li J B, Miller R, Vollhardt D, et al. Thin Solid Films, 1998, 327: 84.
[17] Nag K, Boland C, Rich N, et al. Biochim. Biophys. Acta, 1991, 1068: 157.
[18] Hossain M M, Iimura K I, Kato T. Journal of Colloid and Interface Science, 2008, 319: 295.
[19] McConnell H M，Moy V T. The Journal of Physical Chemistry, 1988, 92: 4520.
