预处理对酶解过程中胶原ACE抑制肽释放的影响

本文探究了酸、碱、热、超声、超高压五种预处理方式对胶原蛋白制备ACE抑制肽的影响。胶原蛋白经预处理后采用碱性蛋白酶酶解制备水解液,对水解液的水解度、ACE抑制率和分子量分布情况进行测定,结果显示碱和超声处理组水解液的水解度、ACE抑制率均高于未处理组,表明这两种预处理方式可能利于胶原三螺旋区位点的暴露;DSC和红外分析预处理后的胶原蛋白结构显示,碱处理改变了胶原蛋白构象特点,影响非共价键的平衡,胶原三螺旋区域的位点被充分暴露,但保持了亚基的完整性,超声处理破坏了胶原螺旋区的共价交联,暴露出更多疏水性位点,利于碱性蛋白酶酶解;而酸、热和超高压处理主要影响胶原非螺旋区,无法在酶解过程中促进胶原ACE抑制活性肽段的释放。

Effect of Pretreatments on Release of Collagen-derived Angiotensin-converting-enzyme Inhibitory Peptide in Enzymatic Hydrolysis

The effects of five pretreatments (acid, alkali, heat, ultrasound, and high pressure) on the production of angiotensin-converting-enzyme (ACE) inhibitory peptide from collagen were explored. After pretreatment, collagen was hydrolyzed by Alcalase, and the degree of hydrolysis (DH), ACE inhibitory activity, and the molecular weight distribution of the hydrolysate were measured. Results showed that alkali- and ultrasound-treated groups had higher DH and ACE inhibition rate than the untreated group, which indicated that these two pretreatments can favor exposure of sites in the triple-helical region of collagen. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) were used to analyze the structure of collagen, and the results showed that alkali treatment changed the configuration of collagen, affected the balance of non-covalent bonds, and exposed the hydrophobic site completely in the triple-helical region of collagen. However, the integrity of the subunits was maintained. Ultrasound treatment damaged the covalent bonds in the helical region of collagen and exposed more hydrophobic sites, which was helpful for alcalase hydrolysis. In contrast, acid, heat, and high-pressure treatments mostly affected the non-helical region of collagen, and could not promote the release of ACE inhibitory peptide from collagen during enzymatic hydrolysis.