Fig. 4: TR-SSX crystal structures of moxalactam of the active site of L1 MBL.

a L1 active site structure at 150 ms with hydrolyzed moxalactam (in yellow-red-blue), zinc (magenta) and protein residues (in silver-blue-red). b Difference electron density map calculated as F_obs(150 ms)-F_obs(100 ms). The differential map was calculated with Phenix isomorphous difference maps module. Negative electron density showed as red mesh, positive as green mesh. Depicted in the Coot electron density map are countered with a 1.9 σ level. Orange lines illustrate cleaved moxalactam at 150 ms, green lines represent uncut moxalactam at 100 ms. c Distances between atoms key in description of L1 induced β-lactam cleavage reaction (rainbow). d Distances in TR-SSX structures of L1 MBL relative to atom positions in 20 ms crystal structure of L1 MBL (illustrated as a heat-map). e TR changes in distances between zincs and moxalactam atoms modeled in L1 active site, source data is available as Source data file. f Evolution of electron density during cleavage of moxalactam by L1 MBL. The 2Fo-Fc map contoured at 1.0 σ level (carved at 1.4 Å) around moxalactam; maps were depicted as olive mesh for 100 ms, blue mesh for 150 ms, and black mesh for 2000 ms. g Catalytic mechanism proposed for L1 MBL based on TR-SSX experiments.