Compare and contrast serine proteases and aspartic proteases by completing the phrases. drag each answer to the appropriate blank (target). not all answers will be used.

"Serine proteases have a catalytic triad consisting of histidine, asparticacid and serine, whereas aspartic proteases have 2 Asp residues in the active site."

Serine proteases are enzymes that break the bonds between peptides in proteins. A catalytic triad is a group of three amino acids which comprise the active site of several enzymes. In the case of serine proteases, the catalytic triad is placed at the active site of the enzyme and by definition, it is the place where the catalysis occurs. The triad consists of three amino acids: histidine, aspartic acid and serine.

Aspartic proteases are enzymes with more specific catalytic activity since they break dipeptide bonds with hydrophobic residues or a b-methylene group. The active site of this enzyme consists of two aspartate residues for catalysis.

In serine proteases there is a covalent intermediate, whereas aspartic proteases utilize direct nucleophilic attack by water.

A similarity between two mechanisms is that they go through a trigonalplanar intermediate.

Serine protease generates many intermediates during its catalysis, which are bound by covalent bonds. Whereas aspartic proteases abstract a proton from the water molecule and the water is activated. This, in turn, enables the water to perform a nucleophilic attack on the bonds of the substrate.

A trigonal planar is a term referring to a molecular geometry model which consists of one atom at the centre and three atoms at the corners.