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Luminescence. 2016 May;31(3):782-92. doi: 10.1002/bio.3024. Epub 2015 Sep 11.

Study on the interaction of β-carotene and astaxanthin with trypsin and pepsin by spectroscopic techniques.

Author information

1
Department of Chemistry, School of Basic Medicine, Xinxiang Medical University, Xinxiang, Henan, 453003, People's Republic of China.
2
The Clinical Skills Training Center, Xinxiang Medical University, Xinxiang, Henan, 453003, People's Republic of China.

Abstract

β-Carotene and astaxanthin are two carotenoids with powerful antioxidant properties, but the binding mechanisms of β-carotene/astaxanthin to proteases remain unclear. In this study, the interaction of these two carotenoids with trypsin and pepsin was investigated using steady-state and time-resolved fluorescence measurements, synchronous fluorescence spectroscopy, UV-vis absorption spectroscopy and circular dichroism (CD) spectroscopy. The experimental results indicated that the quenching mechanisms of trypsin/pepsin by the two carotenoids are static processes. The binding constants of trypsin and pepsin with these two carotenoids are in the following order: astaxanthin-trypsin > astaxanthin-pepsin > β-carotene-trypsin > β-carotene-pepsin, respectively. Thermodynamic investigations revealed that the interaction between the two carotenoids and trypsin/pepsin is synergistically driven by enthalpy and entropy, and hydrophobic forces and electrostatic attraction have a significant role in the reactions. In addition, as shown by synchronous fluorescence spectroscopy, UV-vis absorption spectroscopy and CD, the two carotenoids may induce conformational and microenvironmental changes in trypsin/pepsin. The study provides an accurate and full basic data for clarifying the binding mechanisms of the two carotenoids with trypsin/pepsin and is helpful in understanding their effect on protein function and their biological activity in vivo.

KEYWORDS:

astaxanthin; pepsin; spectroscopy; trypsin; β-carotene

PMID:
26358735
DOI:
10.1002/bio.3024
[Indexed for MEDLINE]

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