Wang Bei, Heinonen Marina
Department of Food and Environmental Sciences, Food Chemistry, University of Helsinki , P.O. Box 27, FI-00014 Helsinki, Finland.
J Agric Food Chem. 2017 Jan 11;65(1):148-155. doi: 10.1021/acs.jafc.6b04256. Epub 2016 Dec 19.
Protein-tannin interactions on a molecular level were investigated by using a model system containing peptides of α-lactalbumin and berry tannins (procyanidins). Oxidation of isolated tryptic peptide LDQWLCEK (m/z 1034) with procyanidin B2 or procyanidin fraction (PF) isolated from aronia juice was monitored by LC-ESI-MS. Procyanidin B2 and PF showed radical scavenging activities toward oxidation of the peptide with the peptide also preventing procyanidin B2 from degradation. Oxidation enhanced the cleavage of peptide between tryptophan and glutamine. Interaction products arising from WLCEK or WLCE residue and degradation product of procyanidin B2 were also identified using both size exclusion chromatography and LC-MS. Tryptophan and lysine were the amino acids most prone to interact with procyanidin B2. The study shows that protein-tannin interaction takes place during oxidation leading to both degradation of the parent compounds and formation of interaction products. This may in turn affect the quality of protein and tannin containing food.
通过使用包含α-乳白蛋白肽和浆果单宁（原花青素）的模型系统，在分子水平上研究了蛋白质-单宁的相互作用。用从沙棘汁中分离出的原花青素B2或原花青素组分（PF）对分离的胰蛋白酶肽LDQWLCEK（m/z 1034）进行氧化反应，通过液相色谱-电喷雾质谱（LC-ESI-MS）进行监测。原花青素B2和PF对该肽的氧化显示出自由基清除活性，同时该肽也能防止原花青素B2降解。氧化增强了色氨酸和谷氨酰胺之间肽段的裂解。还使用尺寸排阻色谱法和LC-MS鉴定了由WLCEK或WLCE残基与原花青素B2降解产物产生的相互作用产物。色氨酸和赖氨酸是最容易与原花青素B2相互作用的氨基酸。该研究表明，蛋白质-单宁的相互作用在氧化过程中发生，导致母体化合物降解并形成相互作用产物。这反过来可能会影响含蛋白质和单宁的食物的品质。
