The Hydrophobicity of Micro Water Pool and the Interfacial Fluidity of PC-Based W/O Microemulsion Droplet Involved with Reactivity of Phospholipase A₂

Abstract:

The impact of physicochemical character of the W/O microemulsion droplet on the reactivity of phospholipase A₂ (PLA₂) was investigated for optimal design of the micro-reactor. Hydrophobicity of micro water pool and fluidity of micro-scaled interface of W/O microemulsion droplet were dominant factors to determine the appearance of maximum reactivity. Phosphatidylcholine (PC) in this system performed not only as a substrate for PLA₂ but also as an amphiphilic molecule to form W/O microemulsion droplet. The organic phase was composed by isooctane (C₈*) as a main solvent and 1-butanol (C₄) as a co-solvent. The molar ratio was fixed as isooctane:1-butanol =11:1. The water content in the W/O microemulsion was indicated by the molar ratio of H₂O moles to PC moles presented by Wsoln [-](≡[mol-H₂Osoln]/[mol-PC]). By the increasing of the water content from 1 to 5, the reactivity of PLA₂ was remarkably increased from 0.01 to 0.03 [mM･s^-1･mg-PLA₂^-1]. Over 5 of Wsoln range, the reactivity was decreased. The optimal water content was indicated as Wsoln=5 [-]. The hydrophilicity of micro water pool and the interfacial fluidity of the water pool were detected by the signal of the fluorescence probes, Coumarin 343 and TMA-DPH, respectively. The hydrophobicity was decayed with the increasing of the water content. More than 10 of Wsoln, the hydrophobicity was fully decayed and achieved to bulk aqueous one. The interfacial fluidity was decreased with the increasing of the water content. In more than Wsoln of 5, the reactivity was decreased by the decline of the collision frequency between PLA₂ and PC molecule due to lower fluidity of micro-scaled interface.

• Periodical: Key Engineering Materials (Volume 459)
• Pages: 100-108
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.459.100
• Online since: December 2010
• Authors: Keiju Yamazaki, Masanao Imai
• Keywords: Fluidity of Micro-Scaled Interface, Hydrolysis, Hydrophobicity, Phospholipase A₂, Phospholipid, W/O Microemulsion

References

[1] K. Nagayama, S. Matsu-ura, T. Doi and M. Imai: J. Mol. Catal. B: Enzymatic Vol. 4 (1998), p.25.

[2] K. Yamazaki, M. Imai, I. Suzuki: Biochem. Eng. J. Vol. 19 (2004), p.171.

[3] C. Yao, S. Tang, J. Zhang and Y. Yu: J. Mol. Catal. B: Enzymatic Vol. 18 (2002), p.279.

[4] M. M. R. Talukder, Y. Hayashi, T. Takeyama, M. M. Zamam, J. C. Wu, T. Kawanishi and N. Shimizu: J. Mol. Catal. B: Enzymatic Vol. 22 (2003), p.203.

DOI: 10.1016/s1381-1177(03)00035-3

[5] P. K. Schmidli, and P. L. Luisi: Biocatalysis Vol. 3 (1990), p.367.

[6] S. Sugiura, S. Ichikawa, Y. Sano, M. Nakajima, X. Q. Liu, M. Seki and S. Furusaki: J. Colloid Interface Sci. Vol. 240 (2001), p.566.

DOI: 10.1006/jcis.2001.7703

[7] N. Garti, D. Lichtenberg and T. Silberstein: Colloids Surfaces A Vol. 128 (1997) p.17.

[8] R. Abuin, E. Lissi, A. Ceròn and M.A. Rubio: J. Colloid Interface Sci. Vol. 258 (2003), p.363.

[9] M. P. Mora, C. Tourne-Peteilh, M. Charveron, B. Fabre, A. Milon and I. Muller: Chem. Phys. Lipids Vol. 101 (1999), p.255.

DOI: 10.1016/s0009-3084(99)00067-5

[10] K. Yamazaki and M. Imai: Korean J. Chem. Eng. Vol. 25 (2008), p.1439.

[11] T. Yamasaki, O. Kajimoto and K. Hara: J. Photochem. Photobiol. A: Chem. Vol. 156 (2003), p.145.

[12] K. Yamazaki and M. Imai: Colloids and Surfaces A: Physicochem. Eng. Aspects Vol. 293 (2007), p.241.

[13] P. Høyrup, O. G. Mouritsen and K. Jørgensen: Biochimica Biophysica Acta Vol. 1515 (2001), p.133.

[14] K. Naoe, K. Noda, M. Kawagoe, M. Imai: Colloids and Surfaces B: Biointerfaces Vol. 38 (2004), p.179.

DOI: 10.1016/j.colsurfb.2004.02.020

[15] H. Stamatis, A. Xenakis, E. Dimitriadis and F. N. Kolisis: Biotechnol. Bioeng. Vol. 45 (1995), p.33.

[16] S. P. Moulik and B. K. Paul: Advances in Colloid Interface Sci. Vol. 78 (1998), p.99.

[17] A. Chattopadhyay: Chemistry Physics Lipids Vol. 122 (2003), p.3.

[18] M. P. Pileni, J. P. Huruguen and C. Petit: The structure, Dynamics and Equilibrium Properties of Colloidal Systems, edited. By D. M. Bloor and E. Wyn-Jones Publications/ Kluwer Academic Publishers (1990).

DOI: 10.1007/978-94-011-3746-1

[19] L. Silva, A. Coutinho, A. Fedorov and M. Prieto: Biochimica et Biophysica Acta – Biomembranes Vol. 1758 (2006), p.452.

DOI: 10.1016/j.bbamem.2006.03.008

[20] B. Sengupta, J. Guharay and P. K. Sengupta: Spectrochimica Acta Part A Vol. 56 (2000), p.1433.

[21] D. L. Scott and P. B. Sigler: Adv. Protein Chem. Vol. 45 (1994), p.53.

[22] O. G. Berg, M. H. Gelb, M. D. Tsai and M. K. Jain: Chem Rev Vol. 101 (2001), p.2613.

[23] S. H. Edwards, D. Thompson, S. F. Baker, S. P. Wood and D. C. Wilton: Biochem. Vol. 41 (2002), p.15468.

[24] T. Maruyama, M. Nakajima and M. Seki: J. Biosci. Bioeng. Vol. 92 (2001) p.242.