Muscle contractions are caused by the motor protein myosin which consumes the hi

Question

Muscle contractions are caused by the motor protein myosin which consumes the high energy molecule ATP for fuel. The ATP molecules carry a negative charge of 4e, so the active site of the myosin has a positive charge to help the ATP nd the correct place to bind. Consider the following arrangement of an ATP molecule, a myosin binding site (q= +3), a RNA molecule with a charge150e, and a protein carrying a charge 6e. Since these molecules are immersed in water, the dielectric constant is K = 80. Calculate: The electric potential at the ATP molecule's position due to the other molecules. (Let V=0 at innite distance from all charges.) The force vector on the ATP. (Biological forces are typically given in piconewtons or nanonewtons.) The energy required to move the ATP molecule from very far away to its present location. Express your answer in kCal/mol

Explanation / Answer

a) V = sum of kq/r

= 9.0E9*1.6E-19*(6/5.0E-9+3/3.0E-9 -150/200.0E-9)=2.088 V

b) sum forces in the x
Fx = 9.0E9*1.6E-19^2*(-4*3/3.0E-9^2 -150*4/200.0E-9^2 -6*4/5.0E-9^2*3/5)=-4.43 E-10 N

Fy=9.0E9*1.6E-19^2*6*4/5.0E-9^2*4/5=1.77E-10 N

so <-0.443, 0.177 > nN

c) E = q dV = 4.0E-9*2.088=8.35E-9 J per ATP

so 8.35E-9*6.0233E23=5.03E15 J per mole = 1.2E12 kCal/mole

Related Questions

Navigate

• Browse (All)
• Browse M
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.