Collin County Community College Catechol Oxidase Reaction Lab Report

Download the report sheet, complete it, and then submit it via Blackboard email as an attachment.Do not change the format.

All blue shaded areas require answers.

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Introduction: Catechol oxidase reaction

Name of substrates
Name of enzyme
Name of products
Enzyme was extracted from
Color of benzoquinone

I. Preparation of standard tubes

Experiment (dry lab)

Copy the color intensity for the 20 min standard tubes from the slide.

Time (min)	Tube A	Tube B	Tube C
20

II.Specificity

Experiment (dry lab)

Record intensity (scale 0 – 5) using the standards (A-C) as your guide

Time (min)	Tube D	Tube E
20

1. Based on the color intensity of the tubes, which substrate reacts better with catechol oxidase to produce benzoquinone? Choices are catechol (tube D) or hydroquinone (tube E).
2. Does catechol oxidase express specificity? Yes or No.

III.Temperature

At extremely high temperatures and pH, the structure of the enzyme is permanently changed to the point where it can no longer function. This change in structure of the enzyme is described as

Experiment (dry lab)

Record the color of each tube at 20 minutes on a scale of 0-5 using your standards (A-C) as a guide. Plot your results on the graph below and connect the dots.

Time (min)	50C ice water	250C room temp water	400C Water bath	600C Water bath	800C Water bath	1000C Boiling water
20
At what temperature does catechol oxidase work best?

(Fill table using Microsoft insert shapes (or manually graph, scan and embed image into report.)

Experiment (at home lab)

QUESTION

Observe the color of the apple surface. Which slice has produced more benzoquinone, 4°C slice or 25°C slice?

IV.PH

Experiment (dry lab)

Record the color of each tube at 20 minutes on a scale of 0-5 using your standards (A-C). Plot your results on the graph below and connect the dots.

Time (min)	pH 2	pH 4	pH 6	pH 7	pH 8	pH 10	pH 12
20
At what pH does catechol oxidase work best?

(Fill table using Microsoft insert shapes (or manually graph, scan and embed image into report.)

Experiment (at home lab)

QUESTION

Observe the color of the apple surface. Which slice has produced most benzoquinone, pH3 (vinegar), pH7 (water), or pH12 (bleach)?

V.Cofactor

Experiment (dry lab)

Record the color of each tube at 20 minutes on a scale of 0-5 using your standards (A-C).

Time (min)	Tube F	TubeG
20

Tube G has enzyme mixed with EDTA. The EDTA inactivated the cofactor of catechol oxidase.

Is the cofactor (Cu++) necessary? In other words, does catechol oxidase in tube G need its cofactor to function? Yes or No.

QUESTIONS:

1. What type of experiment was done in the lab, quantitative or qualitative?
2. Can you think of a way to improve the experiment to make it less subjective and more reliable? (Hint: color is a type of light being reflected; which instrument measures reflected light?)

After you complete the experiment and collect data,

1. Post a picture of your completed experiment showing the effect of temperature and pH on enzyme function. (2pts)

2. Explain your results in no less than 4 complete sentences. (2pts)

3. Ask a question/ comment on someone’s post from your class/answer a question, in a respectful and thoughtful way. (1pt)