中国农业科学 ›› 2005, Vol. 38 ›› Issue (08): 1652-1657 .

• 园艺 • 上一篇    下一篇

β-乳球蛋白加压凝胶的生成及其物化特性研究

木泰华,孙艳丽,菅野 長右ヱ門   

  1. 中国农科院农产品加工所
  • 收稿日期:2004-11-15 修回日期:1900-01-01 出版日期:2005-08-10 发布日期:2005-08-10
  • 通讯作者: 木泰华

Formation and Physicochemical Properties of Pressure-Induced Gels

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  1. 中国农科院农产品加工所
  • Received:2004-11-15 Revised:1900-01-01 Online:2005-08-10 Published:2005-08-10

摘要: 研究了在30℃ 、800 MPa压力的作用下, 不同加压时间(5~120 min)和不同浓度N-乙基马来酰亚胺 (NEM,1~10 mmol·L-1)对14%(w/v)的β-乳球蛋白(β-Lg)溶液在pH 7.20条件下形成凝胶物理化学特性的影响。结果表明,延长加压时间未对凝胶的硬度和破断应力造成影响。凝胶呈现出类似蜂窝状的多孔网状结构。随加压时间延长,蜂窝状多孔的孔径变大,但其网状结构未受到破坏。在加压时间延长的条件下凝胶保持着高持水力,说明在加压过程中,凝胶内部蛋白质和水的相互作用未产生明显变化。随加压时间延长,用Tris-glycine-EDTA缓冲溶液或含有0.5% SDS和8 mol·L-1尿素的缓冲液溶解凝胶,发现凝胶中蛋白溶解度降低。SDS-聚丙烯酰胺凝胶电泳图谱显示,在2-巯基乙醇不存在的条件下,除了β-Lg单体以外,还检出二聚物、三聚物、四聚物以及高分子聚合体的染色带。相反,在2-巯基乙醇存在的条件下,只检出了单体。此外,在800 MPa条件下添加10 mmol·L-1的N-乙基马来酰亚胺未导致凝胶的生成。表明在pH中性范围内,加压 β-Lg凝胶,主要是通过SH基的氧化和SH/S-S内部交换反应形成的内部分子间架桥而形成。

关键词: 高静水压, β-乳球蛋白, N-乙基马来酰亚胺, 物化特性

Abstract: The effects of different pressuization times (5-120 min) and N-ethlmaleimide (NEM,1-10 mmol·L-1) on physicochemical properties of gels induced from 14% (w/v) β-Lactoglobulin (β-Lg) at pH 7.20 under 800 MPa at 30℃ were investigated. The results showed that the hardness and breaking stress of gels were not influenced by increasing pressurization time. The gel showed network structure like honeycomb. The aperture of structure became larger with increasing pressurization time but not broken.The gels kept a high WHC with increasing pressurization time, suggesting that protein-water interaction in gel was not changed significantly during pressurization. The protein solubilized from gels with Tris-Glycine-Na2EDTA buffer or in the same buffer containing 8 mol·L-1 urea and 0.5% SDS decreased with increasing pressurization time. SDS-PAGE patterns were markedly different depending on the presence of β-mercaptoethanol (β-ME). In the absence of β-ME, the bands of dimer, trimer, tetramer and high molecular aggregates were appreciably detected in addition to monomer. In contrast, in the presence of β-ME, only monomer band was detected. The result suggests that disulfide bonding is the primary driving force for gelation under pressurization. Gels were not induced by adding 10 mmol·L-1 N-ethlmaleimide gelation of β-Lg at 800 MPa and the content of sulfhydryl group decreased. It is, therefore, suggested that the formation of gel from β-Lg under pressurization results from intermolecular cross-linkages via oxidation of thiol groups and sulfhydryl-disulfide interchage reactions at neutral pH.

Key words: Hydrostatic pressure, β-Lactoglobulin, N-ethlmaleimide, Physicochemical properties