In a recent experiment, you identified an amino acid at the active site of an enzyme. Given your knowledge that basic amino acids are generally found at enzyme active sites, which of the following is most likely to be the amino acid that you have found?

W) Histidine [HIS-ti-deen]

X) Aspartate

Y) Serine [SER-een]

Z) Phenylalanine [fen-l-AL-uh-neen]
W) HISTIDINE