SHEET THE SHEET PRESENTED AS *S1* ON SHEET RECORDS BELOW IS ACTUALLY A SIX-STRANDED BETA-BARREL. ...SHEET THE SHEET PRESENTED AS *S1* ON SHEET RECORDS BELOW IS ACTUALLY A SIX-STRANDED BETA-BARREL. THIS IS REPRESENTED BY A SEVEN-STRANDED SHEET IN WHICH THE FIRST AND LAST STRANDS ARE IDENTICAL. SHEET S2 OF THIS MOLECULE IS BIFURCATED. IN ORDER TO REPRESENT THIS FEATURE IN THE SHEET RECORDS BELOW, TWO SHEETS ARE DEFINED. STRANDS 1, 2, 3, 4, 5, AND 7 OF SHEETS S2A AND S2B ARE IDENTICAL.
RESIDUES B 500 - B 504 ARE A TETRAPEPTIDE BOUND IN THE ACTIVE SITE, COVALENTLY LINKED TO OG OF SER ...RESIDUES B 500 - B 504 ARE A TETRAPEPTIDE BOUND IN THE ACTIVE SITE, COVALENTLY LINKED TO OG OF SER 195 AS AN ACYL ADDUCT. IT IS, PRESUMABLY, AN AUTOLYTIC CLEAVAGE PRODUCT. THE EXACT IDENTITY OF THE RESIDUES IS UNCERTAIN AS THE SIDE CHAINS SEEM TO BE DISORDERED. THE ATOM IDENTIFIED AS C UNK B 500 IS ACTUALLY THE CARBONYL CARBON OF AN UNIDENTIFIED AMINO ACID NOT VISIBLE IN THE ELECTRON DENSITY MAP.