Various bioactive peptides are identified from casein hydrolysates. YQEPVLGPVR (PICA), a novel antithrombotic peptide derived from beta-casein (fragment 193–202), was identified by high-performance liquid chromatography – liquid chromatography-mass spectrometry/mass spectrometry. The anticoagulation activity assay showed that this peptide has a strong anticoagulant activity. It was proved that the peptide did not interact with the active site of thrombin to inhibit thrombin, and that it inhibited thrombin activity by binding the exosite-1 of thrombin, which was also confirmed by the fibrinogen clotting time assay. It was shown that PICA prolonged fibrinogen clotting time in a dose-dependent manner. Secondary structures of the thrombin–PICA complex were also measured by circular dichroism to prove that PICA can combine with thrombin. Moreover, Discovery Studio 2017 R2 software was used for molecular docking to provide the potential mechanism for the antithrombotic activity of the peptide. These results suggested that PICA probably can be used as an antithrombotic ingredient in the functional food industry.

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β-酪蛋白的抗凝血肽：鉴定，结构和分子机理

从酪蛋白水解物中鉴定出各种生物活性肽。YQEPVLGPVR（PICA）是一种衍生自β-酪蛋白（片段193-202）的新型抗血栓肽，已通过高效液相色谱-液相色谱-质谱/质谱法进行了鉴定。抗凝活性测定表明该肽具有很强的抗凝活性。已证明该肽不与凝血酶的活性位点相互作用以抑制凝血酶，并且通过结合凝血酶的exosite-1抑制了凝血酶活性，这也被纤维蛋白原凝结时间测定所证实。结果表明，PICA以剂量依赖性方式延长了纤维蛋白原的凝结时间。凝血酶-PICA复合物的二级结构也通过圆二色性进行了测量，以证明PICA可以与凝血酶结合。而且，使用Discovery Studio 2017 R2软件进行分子对接，以提供该肽的抗血栓形成活性的潜在机制。这些结果表明，PICA可以在功能性食品工业中用作抗血栓成分。