question_answer

A sample of enzyme lactase was isolated from the intestinal lining of a calf. Assays were undertaken to evaluate the activity of enzyme sample. The substrate of lactase is the disaccharide lactose. Lactase breaks a lactose molecule in two, producing a glucose molecule and a galactose molecule.

The results of two assays are:

Assay 1

Lactose Concentration (\[%\]w/v) 15 15 15 15 15 15 Concentration of enzyme sample  (\[%\]v/v) 0 5 10 15 20 25 Rate of reaction (\[\mu \] mole glucose \[{{\sec }^{-1}}\]\[{{\operatorname{ml}}^{-1}}\]) 0 25 50 75 100 125 Assay 2

lactone concentration (\[%\]w/v) 0 5 15 20 25 30 Concentration of enzyme sample (\[%\]v/v) 5 5 5 5 5 5 Rate of reaction (\[\mu \]mole glucose \[{{\sec }^{-1}}\]\[{{\operatorname{ml}}^{-1}}\]) 0 15 25 35 40 40 Which of the following statements can be concluded from two assays?

A) The reaction rate of lactase assay is always proportional to the amount of enzyme present.

B) The amount of lactose in an assay has no effect on the rate of reaction.

C) The reaction rate of the lactase assay is proportional to the amount of lactose present.

D) The reaction rate is proportional to the amount of enzyme present at a lactose concentration of \[15%\]w/v.