GSVEFKITSGGNGPAELLKALIQGSGSVTITWEVHGNGNSALELALQLLKGSGTVEFIDGNGN
 --SSSSSS-----HHHHHHHHHH----SSSSSSSS-----HHHHHHHHHH---SSSSSS----
         S                         H                       D

Can you find its active site residues? Motivate your answer in less than 20 words.

Most active sites in nature are one of two:

1. The classical triad Asp-His-Ser
2. Sugar cleavers that tend to have three negative residues one of which must be Asp and another one normally is Glu (third one Asp or Glu).

We also know that active sites tend to sit at the C-terminal end of the strands in α - β - α - β - etcetera proteins. You only find one of each of His, Asp, Ser 'after' the predicted β-strands, and only one D and no Es. So the SHD indicated form the only solution.