... mutants. T he interactingresidues, Glu614, His665, and His667 in molecule A and Thr643,Glu706, and Leu709 in molecule B, are shown in a ball -and- stickrepresentation, whereas th e main c hains ... esidues include: Gly, preceding, and Ala, following the catalytic Ser (positions ) 2and+ 1,respectively),aswellasSer(+11),Thr(+25),fourGlyresidues (+26, +32, +38 and +39), and Pro (+58)(Fig. 2). Moreover, ... Lonproteases.Materials and methodsSite-directed mutagenesis ofE. coliLon proteaseStrains BL21 and HB101 (Stratagene, La Jolla, C A, USA)of E. coli were utilized in this study. Standard procedureswere...