Type and composition
According to metal ions [1] and Enzyme protein The stability of binding can be divided into metalloenzymes and Metal activating enzyme Two types. In metalloenzymes, they are firmly bound together, and metal ions are usually active centers. In metal activating enzymes, they are loosely bound, but the metal ions are enzymatic activity Of activator 。 There are many kinds of metalloenzymes, including zinc 、 iron 、 copper Of enzyme Most, such as iron metalloenzyme cytochrome C. It also contains molybdenum 、 manganese And other metal ions. for example Cytochrome oxidase Besides iron ion, it also contains copper ion. Most β - lactamases have serine residues as their active sites, but there are also a small number of enzymes with metal ions as their active sites. The first enzyme found with metal ions as the active center is cephalosporin enzyme produced by Bacillus cereus, which can be inhibited by EDTA. Later, various bacteria that can produce this kind of enzyme were found all over the world. In 1988, Bush first named the enzyme metallo β - lactamase, or metallo β - lactamase for short.
Metallo β - lactamases are resistant to β - lactamase inhibitors and can hydrolyze almost all β - lactam antibiotics (including imipenem). The enzyme has been found in Aeromonas, Stenotrophomonas maltophilia, Burkholderia cepacia, among which the imipenem resistance of Stenotrophomonas maltophilia is mediated by chromosomes, while Bacteroides fragilis klebsiella pneumoniae Plasmid mediated Mutant It has been reported in Japan. The metallo β - lactamase IMP-1 produced by Serratia marcescens can move on intl3, which is similar to the zygote, and has spread to Pseudomonas aeruginosa 、 klebsiella pneumoniae And Alcaligenes. Metallase can hydrolyze carbapenems and the fourth generation cephalosporins developed. Metal beta lactamases have a wide range of spread And has the potential to treat almost all β - lactam antibiotics hydrolysis Activity is the strongest known β - lactamase. 
