ABSTRACT
The binding mechanism between pterostilbene ( PTE) and human serum albumin ( HSA) was investigated by fluorescence spectrometry and surface enhanced Raman spectroscopy (SERS) under simulated physiological conditions. The experiment result showed that the effect between PTE and HSA was a static fluorescence quenching with F?rsterˊ s non-radioactive energy transformation, and PTE could bind HSA strongly with a 1: 1 molar ratio. The binding distances between PTE and HSA was 1. 495 nm, and the binding constants (KA) between PTE and HSA were 1. 12 × 104 (298 K), 4. 07 × 104 (304 K) and 2. 45 × 105 L/ mol (310 K). SERS revealed that PTE combined with HAS by methoxy group. Thermodynamic data indicated that the interaction between PTE and HSA was mainly hydrophobic interaction. Marker competition experiments pointed out that the primary binding site for PTE was located at site Ⅲ in HSA. Three-dimensional, synchronous fluorescence spectrum and SERS showed that the conformation of HSA changed apparently with the addition of PTE, resulting in the tryptophan residue of HSA exposing to a less hydrophobic micro-environment. However, the conformation of PTE did not change apparently with the addition of HSA.