Structure
The dimensions of MurI is approximately 35 Å × 40 Å × 45 Å and consists of two compact domains of α/β structure. With the active site in between the two domains, the N-terminal domain contains residues 1-97 and 207-264 while the C-terminal domain includes residues 98-206. This allows the enzyme to produce L-isomer from D-glutamate. Also, the N-domain is composed of five-stranded β-sheets compared to four-stranded β-sheets of C-domain. These structural specifications are not identical between MurI of different species; S. pyogenes and B. subtilis actually possess the most structurally similar MurI enzymes found as of now. It is also not rare to find MurI as a dimer.
The active site, as it is evenly between the N-domain and C-domain, is also between the two cysteine residues. It is accessible to solvents, as several water molecules, such as W1, are found in the active site. In some species, the active site also incorporates sulfate ions to undergo hydrogen bonding on the amide backbone and the side chains.
Read more about this topic: Glutamate Racemase
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