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以菠萝蛋白酶为催化剂从L-酪氨酸甲酯聚合得到寡聚L-酪氨酸(O-L-Try)。 以0.8 U/mL蛋白酶在体积分数为7.5%的二甲亚砜(DMSO)缓冲液(pH=7.5,0.2 mol/L)中催化0.23 g/mL L-酪氨酸甲酯在50 ℃下聚合反应5 h后,O-L-Try产率达到65%。 通过基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)、氢核磁共振波谱仪(1H NMR)、拉曼光谱、傅里叶变换红外光谱仪(FTIR)等技术手段表征了O-L-Try结构和性能特征。 结果表明,MALDI-TOF-MS测定的O-L-Try的聚合度主要为10。 1H NMR谱图分析得到的O-L-Try的平均聚合度为8。 拉曼光谱显示,O-L-Try的肽键特征峰位于1623 cm-1(酰胺Ⅰ带)、1447 cm-1(酰胺Ⅱ带)、1270 cm-1(酰胺Ⅲ带)和648 cm-1(酰胺Ⅳ带)。 相似文献
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Chanikan Sonklin Adeola M. Alashi Natta Laohakunjit Rotimi E. Aluko 《Molecules (Basel, Switzerland)》2021,26(6)
The aim of this work was to characterize the antioxidant properties of some of the peptides present in bromelain mung bean meal protein hydrolysate (MMPH). The MMPH was subjected to two rounds of bioassay-guided reversed-phase HPLC separation followed by peptide identification in the most potent fractions using tandem mass spectrometry. Twelve antioxidant peptides, namely, HC, CGN, LAN, CTN, LAF, CSGD, MMGW, QFAAD, ERF, EYW, FLQL, and QFAW were identified and assayed for antioxidant properties. CTN, HC, CGN, and CSGD were the most potent (p < 0.05) DPPH radical scavengers with EC50 values of 0.30, 0.29, 0.28, and 0.30 mg/mL, respectively, which are lower than the 0.03 mg/mL obtained for reduced glutathione (GSH). CTN, HC, CGN, and CSGD exhibited the most potent (p < 0.05) scavenging activities against hydroxyl and superoxide radicals with EC50 values that are similar to those of GSH. The cysteine-containing peptides also had stronger ferric reducing antioxidant power and metal chelation activity than peptides devoid of cysteine. In contrast, MMGW, ERF, and EYW had poor radical scavenging and metal chelation activities. We conclude that the availability of the sulfhydryl group may have enhanced antioxidant potency while the presence of bulky groups such phenylalanine and tryptophan had an opposite effect. 相似文献
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果菠萝蛋白酶在有机溶剂微扰时的分子折叠与活力变化的研究 总被引:9,自引:0,他引:9
本文用荧光、紫外差示及CD光谱研究果菠萝蛋白酶经甲醇、乙醇、乙二醇微扰后的构象与活力变化情况.酶的荧光强度随有机溶剂浓度增大而增强,表明Tyr、Trp微环境发生明显变化。232nm和285nm处出现紫外差吸收正峰。前峰与酶分于折叠的变化有关,而后峰与Tyr、Trp微环境的变化相关.甲醇、乙醇微扰后,天然酶的208nm和225nmCD双负峰逐渐加强,而乙二醇微扰后,225nm负峰加强。208nm负峰减弱并红移直至完全消失,说明酶分子完全伸展. 相似文献
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