Question about Protein A purification of IgG

[aeon]

I am a Med.Sci. student who is really desiring the answers to these two
questions for an upcoming report.

1. What is the molecular basis for the selective binding of IgG by protein
A?
2. What is the difference between Protein A and Protein G in relation to
their Ig class binding specificities?

Thank you for your response.


Aeon