Question

Many enzymes are inhibited irreversibly by heavy metal ions such as Hg2+ , Cu2+ , or Ag+ , which can react with essential sulfhydryl groups to form mercaptides. Enz−SH+Ag+⟶Enz−S−Ag+H+ The affinity of Ag+ for sulfhydryl groups is so great that Ag+ can be used to titrate −SH groups quantitatively. To 10.0 mL of a solution containing 1.3 mg/mL of a pure enzyme, an investigator added just enough AgNO3 to completely inactivate the enzyme. A total of 0.436 μmol AgNO3 was required. Calculate the minimum molecular weight (????r) of the enzyme.

Answer 1

Answer:

The minimum molecular weight of the enzyme is 29.82 g/mol

Explanation:

Step 1: Given data

The volume of the solution = 10 ml = 10*10^-3L

Molarity of the solution = 1.3 mg/ml

moles of AgNO3 added = 0.436 µmol = 0.436 * 10^-3 mmol

Step 2: Calculate the mass

Density = mass/ volume

1.3mg/mL = mass/ 10.0 mL

mass = 1.3mg/mL *10.0 mL = 13mg

Step 3: Calculate minimum molecular weight

Molecular weight = mass of the enzyme / number of moles

Molecular weight of the enzyme = 13mg/ 0.436 * 10^-3 mmol

Molecular weight = 29.82 g/mole

The minimum molecular weight of the enzyme is 29.82 g/mol