Purified 1.) actin and myosin were added to solution and viscosity increased. ATP was added and it decreased the viscosity. Explain oxidation A. Mysosin binds to and spontaneously dissociates from act filaments over time B. My spontaneously binds to act and ATP addition causes myosin and actin to dissociate C. Myosin spontaneously binds to actin and ATP addition causes actin to depolymerize D. Myosin binds act, increasing the viscosity ATP then binds to actin causing act and myosin to dissociate there by decreasing the viscosity. ATP does not bind to actin, it binds to myosin. 2.) Why do muscle fibers stretched beyond a certain point lose their ability to contract? A. ATP no long available B. The separation of Z-lines tears the thick filaments in half C. The thick and thin filaments no longer overlap D. overstretched muscles do not lose their ability to contract
3.) Rigor mortis occurs when. A. there is no more ATP to attach myosin actin B. inorganic phosphate does not dissociate which inhibits the powerstroke C. There is no more ATP so myosin is left bound to actin. If we want our enzymes to work maximally- what do we have to guarantee? - Substrate concentration than more 10 fold above Km. How do we measure a Michaelis menten Kinetics?
What is the reaction velocity when [s] = km? a 7.8 17.8 28 35 Table: [s} V 0 0 5 9 10 17 15 20
20 25 30 35 40 45
23 27 30 35 35.3 35
The V mas is about 35 microMolars. so by dividing 35 by 2 (the point when Vmas = km) you get km of 17.8 What is the km calue of the experiment? 2.5 x 10^-6 M 2.5 x 10^-6 M-1 1 x 10^ -5 M 1 x 10^-5 M M -1 Another parameter km = [s] where the velocity of the reaction is half the maximal km=kd when k2 is much smaller than k-1 Vmax = maximal velocity of the reaction when [s] is not rate limiting) Kcat[s-1] = catalytic constant or turnover; how much substrate is converted by the specific enzyme per second kcat/Km{m-1S-1] = catalytic (kinetic) efficiency (specificity constant) how fast an enzyme works, once it encounters its substrate 3. What would happen if the enzyme conc were not constant dure the masurment of reaction velocity as a function of substrate concentration? a. V maz would reamin constant but V would chane V max would remain constant and Km would chane Vmax would change but Km would remain constant cannot predict what would happen.
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