Aeromonas proteolytica

CW line-shape simulation. Simulation of the EPR spectrum of di-copper-substituted aminopeptidase from Aeromonas proteolytica found a zero field splitting that corresponded to an interspin distance of about 5 A, which is in good agreement with the X-ray crystallographic value of 4.93 A.55... 

In homo-dinuclear systems, such as two copper(ll) ions, no large effects are expected on the electron relaxation rates as the two metal ions relax at the same rate. However, some other relaxation mechanisms are operative, giving rise to faster electron relaxation rates (dementi and Luchinat, 1998). Consequently, nuclear relaxation is slower than in single copper(ll) systems. Several examples from model complexes are available (Brink et al., 1996 Murthy et al., 1997), as well as from a copper(ll)-substituted zinc enzyme, the aminopeptidase from Aeromonas proteolytica (Holz et al., 1998). In contrast, few NMR studies on native copper proteins containing two coupled copper (II) ions have been reported so far (Bubacco cf a/., 1999). 

Bzymek, K.P., and Holz, R.C. (2004). The catalyhc role of glutamate 151 in the leucine aminopeptidase from Aeromonas proteolytica. J Biol Chem 279 31018-31025. 

Aminopeptidases are counterparts to carboxypeptidases, removing N-terminal amino acids. However, unlike the carboxypeptidases, they contain dinuclear zinc sites. They fall into two groups, the first of which includes the leucine aminopeptidase from bovine lens, while the second includes the leucine aminopeptidases AAP from Aeromonas proteolytica and SAP from Streptomyces griseus (Figure 12.15). The mechanism of the AAP enzyme has been well studied, and may well represent a general catalytic mechanism for peptide hydrolysis by metal-lopeptidases with a cocatalytic active site.ki. 

Chewier, B., Schalk, C., D Orchymont, H., Rondeau, J.-M., Moras, D., Tarnus, C. Crystal structure of Aeromonas proteolytica ami-nopeptidase a prototypical member of the co-catalytic zinc enzyme family. Structure, 1994, 2, 283-291. 

Figure 6 The active site structures of (left) bovine lens leucine aminopeptidase (pdb ILAM) and (right) Aeromonas proteolytica leucine aminopeptidase (pdb 1 AMP). The zinc ions are in dark gray, carbon atoms in light gray, oxygen atoms in white, and nitrogen atoms in black. Hydrogen bonding interactions are indicated...

Figure 8 Mechanism of peptide hydrolysis proposed for the leucine aminopeptidase from Aeromonas proteolytica. Protein ligands to the dizinc site are shown only in the first panel (at top left) (reproduced...

Aeromonas proteolytica aminopeptidase [a-Aminoacylpeptide hydrolase (Aeromonas proteolytica)] (3.4.11.10) is produced. [A zinc enzyme. Acts most rapidily on L-leucylpeptides, amide and B-naphthylamide. Does not cleave Glu-and Asp-bonds. Similar aminopeptidases were isolated from E, coli and Staphylococcus thermophilus. ] Thermophilic aminopeptidase [a-Aminoacylpeptide hydrolase] (3.4.11.12) is produced. [Metalloen-zymes of high temperature stability and of broad specificity, releasing all N-terminal amino acids, including arginine and lysine. Isolated from Bacillus St ear othermophilus, Talaromyces duponti, Mucor. ]... 

After iron, the zinc ion (Zn +) is the second most ubiquitous metal in natural biological systems. More than 300 molecular structures that involve the functionality of Zn + proteins and Zn + enzymes have been reported. The role of Zn + in Zn +-containing proteins can be classified into three categories (1) structural factors in zinc finger proteins and zinc(II) enzymes such as alcohol dehydrogenase, (2) catalytic factors as in zinc(II) enzymes, including carbonic anhydrase and alcohol dehydrogenase, and (3) co-catalytic factors as found in some aminopeptidases such as the enzyme from Aeromonas proteolytica (Scheme 3.1). 

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