Subject: What is the effect of fat content on the effectiveness of chymosin and why?

If you try to make a cheese out of skim milk, which has the same protein 
content as whole milk, the skim will result with a much smaller curdle mass 
than the whole.  I'm confused as to whether it is because the fat in the whole 
milk is sticking to the protein(due to it's insolubility, or if the fat just 
helps the enzyme to work better.  

Re: What is the effect of fat content on the effectiveness of chymosin and why?