Fig. 7: Hydrogen bonding pattern of the catalytic water molecule OW10 in the active site of CTX-M-14 with bound boric acid and bound glycerol boric acid diester. | Communications Chemistry

Fig. 7: Hydrogen bonding pattern of the catalytic water molecule OW10 in the active site of CTX-M-14 with bound boric acid and bound glycerol boric acid diester.

From: Time-resolved crystallography of boric acid binding to the active site serine of the β-lactamase CTX-M-14 and subsequent 1,2-diol esterification

Fig. 7

The active site of the (a) bound boric acid and (b) glycerol boric acid diester is shown at the 10 s delay time point. OW10 is hydrogen bond donor and acceptor to the boric ester of Ser70 (2.6 Å/2.8 Å). The tetrahedral hydrogen bonding pattern of OW10 is completed by Glu166 (2.6 Å) and Asn170 (2.5 Å). Hydrogen bonds of OW10 to GBE are longer than to BAB (2.8 Å/3.2 Å) while the hydrogen bonding pattern with Glu166 (2.5 Å) and Asn170 (2.6 Å) remains similar. The boron atom is positioned at a distance of 3.0 Å (BAB, 10 s) or 3.4 Å (GBE, 10 s) from the catalytic water OW10. Thus, the catalytic water could perform a nucleophilic attack on the boron atom, leading to the reversible hydrolysis of the boric acid serine ester linkage in BAB and GBE. Potential hydrogen bond distances (Å) are indicated by dashed lines.

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