Glutamic acid structural classification

Fig. 8.1 Classification of metallopeptidases by zinc-binding motifs. The major amino acid motif in zincins has two histidine residues that coordinate with the metal ion and a glutamate residue (E) for catalysis. A third residue that coordinates with the metal may be glutamate, aspartate (D), or histidine. In metzincins, the third coordinating residue is histidine or aspartate (H/D), but the name is taken from the presence of a downstream invariant methionine residue (see Fig. 8.2 and text). The red type indicates enzymes or enzyme subfamilies encoded in the human genome (Slightly modified from Fig. 1A of F.X. Gomis-Ruth, Structural aspects of the metzincin clan of metal-loendopeptidases. Mol. Biotechnol. 24(2) 157-202, 2003)...

Peptidases including keratinases are hydrolases able to hydrolyze peptide bonds in proteins and peptides. They are classified using three different approaches (1) the chemical mechanism of catalysis (based on the catalytic amino acid or metal ion at then-active site, represented by serine, cysteine, threonine, aspartic, asparagine, glutamic and metallocatalytic type), (2) the catalytic reaction (this type of classification depends on the selectivity for the bonds that the peptidases will hydrolyze), and (3) the molecular structure and homology. In this latter approach, amino acid... 

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