Binding of lambda-carrageenan (a food additive) to almond cystatin: An insight involving spectroscopic and thermodynamic approach

作者：Siddiqui Azad Alam; Feroz Anna; Khaki Peerzada Shariq Shaheen; Bano Bilqees^*

来源：International Journal of Biological Macromolecules, 2017, 98: 684-690.

DOI：10.1016/j.ijbiomac.2017.01.143

• Phytocystatin
• lambda-Carrageenan
• Almond milk
• Spectroscopy
• ITC

Carrageenan is a high molecular weight linear sulphated polysaccharide, primarily used in food industry as gelling, thickening, and stabilizing agent. Almond milk prepared from almonds is low in fat, but high in antioxidants, energy, proteins, lipids and fibre. Purified almond cystatin was incubated with increasing concentrations of carrageenan at 25 degrees C for different time interval and significant loss in inhibitory activity was observed. Interaction between carrageenan and cystatin resulted in complex formation as depicted by the decrease in fluorescence intensity with increase in the concentration of carrageenan. Stern-volmer analysis of fluorescence quenching data showed binding constant to be 1.84 +/- 0.20 x 10(4) M-1 and number of binding sites close to unity. These results were further confirmed by supporting results obtained in UV-vis spectroscopy. FTIR analysis shows significant shift in the peak intensity and this change clearly depict change in the structure of cystatin from that of a helix to beta-sheet. CD spectra further confirmed the structural transition of the cystatin from et helix to beta-sheet structure on interaction with increased concentrations of carrageenan. The contributing thermodynamic parameters were determined by ITC. The negative Delta H degrees and positive T Delta S degrees values suggest involvement of electrostatic forces and hydrophobic interaction in the formation of the X-carrageenan-cystatin complex.

• 出版日期2017-5