Question

prepare 500 ml of a reaction buffer containing .075% MgCl2, 200 mM glucose, 900nM ATP and 100mM Tris-Cl, pH 7.5.In addtion you have 20% MgCl2 stock solution and the lab freezer has 10mM ATP that you can dilute to the correct concentration.

stock solutions previously prepared:

500ml of 1.5M glucose----- 135.12 grams glucose

2 L of 1.8M Tris buffer at pH 7.5------- 87.5234 grams base and 252.56 grams acid

Answer 1

Let us calculate the required quantity for each solution to get 500 ml of reaction buffer solution

1) 0.075% MgCl2:

   we have 20% stock solution hence required solution = 0.075 x 500/20 = 1.875 ml

2) 200 mM glucose

    We have stock solution 500ml of 1.5M glucose, required solution = 200 mM X 500 ml / 1.5 M

                                                                                                             = 200 x 10^-3M X 500 ml/ 1.5 M = 66.6 ml

3) 900nM ATP :

     We have stock solution of 10mM ATP , hence required solution = 900 nM X 500 ML/ 10 mM

                                                                                                            = 900 x 10^-9 M x 500 ml/ 10 x 10^-3 M

                                                                                                             = 0.045 ml

4) 100mM Tris-Cl, pH 7.5:

     We have stock solution of 2 L of 1.8M Tris buffer at pH 7.5, required solution = 100 mM X 500 ML / 1.8 M

                                                                                                                                = 10 x 10-3 M x 500 ml /1.8 M

                                                                                                                                 =   2.77 ml

As calculated above mix all the required solutions and dilute upto 500 ml, so that you will get your solution.