Adami Raffaella, Cintio Orietta, Trombetta Giorgio, Choquet Daniel, Grazi Enrico
Dipartimento di Biochimica e Biologia Molecolare, Università di Ferrara, Via Borsari 46, 44100 Ferrara, Italy.
Biochemistry. 2002 May 7;41(18):5907-12. doi: 10.1021/bi0116745.
The effects of coupling with tetramethylrhodamine-5-iodoacetamide and of the decoration with tropomyosin and with myosin subfragment 1 on the elastic properties of F-actin filament are investigated. At 22 degrees C, in 15 mM orthophosphate and 3 mM MgCl2, tetramethylrhodamine F-actin displays a yield strength of 3.69 +/- 0.213 pN and an elastic modulus by stretching of 0.91 MPa. Decoration with tropomyosin increases the yield strength of tetramethylrhodamine F-actin to 10.51 +/- 0.24 pN and the elastic modulus by stretching to 23-75 MPa. Mixtures of myosin subfragment 1 and tetramethylrhodamine F-actin at the 0.2:1, 0.4:1, 0.6:1, 0.8:1, and 1:1 molar ratios are also studied. Both yield strength and the elastic modulus by stretching are found to increase progressively with the ratio. At the 1:1 molar ratio, the yield strength is 15.81 +/- 0.26 pN and the elastic modulus by stretching is 13.45 to 40 MPa. Decoration of tetramethylrhodamine F-actin with both tropomyosin and myosin subfragment 1, at the 1:1 molar ratio with the actin monomer, produces filaments with an yield strength of 22.3 +/- 0.48 pN.
研究了与四甲基罗丹明 - 5 - 碘乙酰胺偶联以及用原肌球蛋白和肌球蛋白亚片段1修饰对F - 肌动蛋白丝弹性特性的影响。在22℃、15mM正磷酸盐和3mM氯化镁条件下，四甲基罗丹明F - 肌动蛋白的屈服强度为3.69±0.213 pN，拉伸弹性模量为0.91MPa。用原肌球蛋白修饰可使四甲基罗丹明F - 肌动蛋白的屈服强度提高到10.51±0.24 pN，拉伸弹性模量提高到23 - 75MPa。还研究了肌球蛋白亚片段1与四甲基罗丹明F - 肌动蛋白在0.2:1、0.4:1、0.6:1、0.8:1和1:1摩尔比下的混合物。发现屈服强度和拉伸弹性模量均随比例逐渐增加。在1:1摩尔比时，屈服强度为15.81±0.26 pN，拉伸弹性模量为13.45至40MPa。用原肌球蛋白和肌球蛋白亚片段1以与肌动蛋白单体1:1摩尔比修饰四甲基罗丹明F - 肌动蛋白，产生的丝的屈服强度为22.3±0.48 pN。
