How to draw the structure of this tetrapeptide:
Ala-Ser-Tyr-Thr© BrainMass Inc. brainmass.com December 19, 2018, 9:23 pm ad1c9bdddf
Since alanine is listed first, this one must be the N-terminal. That means that it will expose its free NH2 group. Since threonine is listed last, it is the C-terminal. That means that it will have its COOH group free and exposed. We know this because primary structure of proteins are always listed with the N-term first.
The other piece of information we need is ...
This solution explains structures of tetrapeptide and describes bonding between amino acids.