Photon Factory Activity Report 2016 #34 (2017)

BL-6A/2015G139

Structural Characterization of Association of Seaweed Polysaccharide and Protein in
Aqueous Solutions by Small Angle X-ray Scattering
Rina Miyauchi1, Thu Thi Minh Quach2 , Thuy Thi Thu Thanh 2, Yoshiaki Yuguchi1*
1Faculty of Engineering, Osaka Electro-Communication University, 18-8 Hatsu-cho, Neyagawa,Osaka 572-8530, Japan
2
Institute of Chemistry, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau
Giay, Hanoi, VietNam

3 Results and Discussion
Figure 1 shows the Kratky plots (q2I(q) vs q, where I(q)is scattering intensity and q is the magnitude of scatteringdefined by (4)sin() with  the wavelength of incident
beam, 2scattering angle) for 0.5% sulfatedpolysaccharide (UL-1), 0.25 %lysozyme, and their
mixture in 0.5M NaCl. The clear peak in scattering fromin 0.5 M NaCl
UL-1
Lysozyme
mixture150

linear sum.

100

22 Experiment
The sulfated polysaccharide sample (named UL-1) wasextracted from green seaweed Ulva Lactuca, collected at
central coasts of Vietnam. The chemical composition ofUL-1 was analyzed as mainly consisting of rhamnose,
uronic acid and sulfate groups. Lysozyme was used as theprotein sample.
SAXS experiments were carried out at BL-6A
experimental station in Photon Factory, Tsukuba, Japan.
The X-ray beam from synchrotron radiation was used. An
incident X-ray beam was monochromatized to  = 0.15
nm and focused to the position of the detector with a bent
focusing mirror. The scattered X-ray was detected byPILATUS positioned at a distance of about 1 meter fromthe sample holder. The solutions were injected in a flatcell of 0.3 cm path-length made of glass with quartz
windows (20 m thick).

lysozyme can be found in 1 nm-1 of q, due to theparticular shape of protein. The profile of UL-1 has theupturn in smaller angle region and reflects chain structure
in other region. The scattering from mixture indicatesstrong upturn for high degree of aggregation. This meansthat the anionic polysaccharide interacts and associateswith cationic protein. Figure 1 also shows the linear sumof scattering from UL-1 and lysozyme, and the difference
from scattering data of mixture sample proves theinteraction of polysaccharide and protein.

q l (q)

1 Introduction
Polysaccharides in seaweeds are almost polyelectrolyte
as carrageenan and alginate, which have sulfate groups
and carboxyl groups. They are used as food additives orgelling agent, because their aqueous solutions show highviscosity or gel state at various conditions. Thesebehaviors are related with the solution structure ofpolysaccharide and their assembly structure at molecularlevel or nano-scale.
Recently, the sulfated polysaccharide as fucoidan,
reveals various physiological activities, as antiviral,antitumor, and so on. In order to understand thephysiological activity mechanism, it is very important toelucidate the structure of association between protein andelectrolyte polysaccharide.
In this study, structural characterization of associationof marine polysaccharide and protein is examined bysmall angle X-ray scattering (SAXS) [1].

5000123-1q , nm

45Fig. 1: Kratky plots for SAXS from 0.5% sulfatedpolysaccharide (UL-1), 0.25% lysozyme, and their
mixture in 0.5M NaCl.
References[1] Thuy Thi Thu Thanh, Van Thi Thanh Tran, YoshiakiYuguchi, Thuy Thi Thanh Tran, Ly Minh Bui and Tai
Tien Nguyen, Marine Drugs, 11, 2431-2443 (2013)* yuguchi@osakac.ac.jp