Subject: Can you please explain the process of enzymatic oxidation in apples?

My friend and I are doing a science fair project on apple oxidation.  We 
researched that enzymatic oxidation is what causes the apple to turn brown when 
in contact with oxygen.  The oxygen reacts with an enzyme in the cells of 
apples called polyphenol oxidase or tyrosinase.  We would like to know in more 
detail how the chemical reaction works.  
Also, we experimented with different types of apples: Braeburn, Golden, Red, 
Granny Smith, and Macintosh.  Our results showed that Granny Smith, then Golden 
Delicious, browned the least.  We made a theory based on those results that 
apples with paler peel or skin has a slower oxidation process.  Is that true?  
or is it because of the amount of acidity in the apple?  thank you for your 
attention and please respond as soon as possible.

Re: Can you please explain the process of enzymatic oxidation in apples?