A example of a long term firness goal would be "C".
Protein is a polymer of amino acids. And is made up of peptide chains. There are 5 types of proteins structural proteins storage proteins hormonal proteins enzyme proteins immunoglobulins proteins
This question is severely broad as it all depends on a number of factors. Ibcan however provide this link with a table that you may find helpful.
http://www.businessinsider.com/at-what-temperatures-can-you-get-frostbite-or-hypothermia-2015-2