Effects of chemical modification, tropomyosin, and myosin subfragment 1 on the yield strength and critical concentration of F-actin.
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.
Adami
Raffaella
R
Dipartimento di Biochimica e Biologia Molecolare, Università di Ferrara, Via Borsari 46, 44100 Ferrara, Italy.
Cintio
Orietta
O
Trombetta
Giorgio
G
Choquet
Daniel
D
Grazi
Enrico
E
D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004548:Elasticity / Q000187:drug effects; D018482:Muscle, Skeletal; D015879:Myosin Subfragments / Q000378:metabolism*; D011817:Rabbits; D012235:Rhodamines / Q000378:metabolism* / Q000494:pharmacology; D014335:Tropomyosin / Q000378:metabolism*
D000199:Actins; D015879:Myosin Subfragments; D012235:Rhodamines; D014335:Tropomyosin; C034996:tetramethylrhodamine iodoacetamide