For questions 13-15, refer to the following table: Enzyme Km (mol/L) 2.6x10^-2 5x10^-6 7.9x10^-3 9.5x10^-5 kcat (s^-1) 4x10^5 800 790 1.4x10^4 carbonic anhydrase fumarase ribonuclease acetylcholinesterase 13. (1 point) Which is the most "efficient" enzyme? 14. (1 point) Calculate the initial reaction velocity for acetylcholinesterase (corresponding to the initial few percent of substrate consumed): Assume a total enzyme concentration of 1 nM and substrate concentration of 100 mM. Show your work. 15. (1 point) For ribonuclease, what concentration of substrate is needed to produce half the velocity that would be obtained in the limit of an "infinitely high" concentration of substrate? 16. (1 point) Would an increase in kcat be expected to affect Vmax? Why? 17. (1 point) Would an increase in Km be expected to affect Vmax? Why? 18. (2 points) Please provide short answer responses to the following: a) (1 point) What distinguishes Kd from Km? Under what conditions are Kd and Km equal? b) (1 point) Is Ki more similar to Kd or Km? Why?