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Purification and characterization of barley lipase.

机译：大麦脂肪酶的纯化和表征。

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摘要

Although the isolation of barley lipase has been previously reported, there has been very little study done on its physical and chemical properties. Barley lipase is a membrane-bound enzyme, and extraction of lipase activity is aided by inclusion of 1–2% Triton X-100. Stability of lipase activity was measured during an incubation period of 48 hr in the presence of 2% Triton X-100. There was only a small decrease in lipase activity (2–5%), indicating that barley lipase activity is very stable in this detergent. The activity of lipase in sound barley kernels is low but increased (up to 45-fold) during germination with a maximum activity at day seven. Barley lipase in crude extracts has a maximum activity at 31°C and at pH of 6.8. Its activity was increased (30%) by the addition of 10–20 mM Ca2+ or Mg2+ . Very little effect was observed with K+ and Na + ions. Barley lipase was purified by anion exchange chromatography (Mono Q, gel filtration (Sephacryl S-200 HR), and chromatofocusing (Mono P). Two lipase activities were separated by chromatofocusing, and were referred to as Lipase 1 and Lipase 2. Lipase 1 has an apparent isoelectric point (pl) of 4.6, maximum activity at pH 7.0, and a temperature optimum of 37°C. The apparent Michaelis constant (Km) of Lipase 1 for triolein as substrate was 3.4 mM. Lipase 2 has a pI of 5.0, maximum activity at pH 6.8, and a temperature optimum of 35°C. The apparent Michaelis constant (Km) value of Lipase 2 for triolein as substrate was determined to be 5 mM. SDS-PAGE showed that both Lipase 1 and Lipase 2 had very high relative molecular mass (approximately 185,000 and 160,000, respectively).
机译：尽管以前已经报道了分离大麦脂肪酶的方法，但对其理化性质的研究很少。大麦脂肪酶是一种结合膜的酶，通过加入1-2％的Triton X-100有助于提取脂肪酶活性。在存在2％Triton X-100的情况下，在48小时的孵育过程中测量了脂肪酶活性的稳定性。脂肪酶活性只有很小的下降（2-5％），表明这种洗涤剂中的大麦脂肪酶活性非常稳定。大麦仁中脂肪酶的活性较低，但在发芽过程中增加（最高45倍），在第七天达到最大活性。粗提物中的大麦脂肪酶在31°C和pH值为6.8时具有最大活性。加入10–20 mM Ca 2 + 或Mg 2+ 可提高其活性（30％）。用K + 和Na + 离子几乎观察不到效果。大麦脂肪酶通过阴离子交换色谱法（Mono Q，凝胶过滤（Sephacryl S-200 HR）和色谱聚焦法（Mono P）纯化，通过色谱聚焦法分离出两种脂肪酶活性，分别称为脂肪酶1和脂肪酶2。脂肪酶1表观等电点（pl）为4.6，在pH 7.0时具有最大活性，最适温度为37°C。对于以油酸甘油酯为底物的脂肪酶1的表观米氏常数（Km）为3.4 mM。脂肪酶2的pI为1。 5.0，最大活性，pH 6.8和最适温度为35°C。以三油精为底物的脂肪酶2的表观米氏常数（Km）值确定为5 mM.SDS-PAGE显示脂肪酶1和脂肪酶2具有相对高的相对分子质量（分别约为185,000和160,000）。

著录项

  • 作者

    Tuhkanen, Adela Cruz.;

  • 作者单位

    North Dakota State University.;

  • 授予单位 North Dakota State University.;
  • 学科 Agriculture Food Science and Technology.
  • 学位 Ph.D.
  • 年度 2001
  • 页码 86 p.
  • 总页数 86
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 农产品收获、加工及贮藏;
  • 关键词

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