Asparaginase: Difference between revisions

The first L-asparaginase structure was published and deposited in the PDB in 1993 for the EcAII enzyme <ref>PMID:8434007</ref> and may serve as an example of a Class 1 type II enzyme <scene name='52/525144/3eca_cartoon/7'>EcAII</scene> ('''Figure EcAII_3eca'''). Structure of Class 1 type I enzymes is exemplified by <scene name='52/525144/Ecai_2p2n/1'>EcAI</scene><ref>PMID:17451745</ref>, whereas Class 2 type III enzymes may be represented by EcAIII<ref>PMID:15159592</ref><ref>PMID:18334484</ref> ('''Figure EcAIII_2zal'''). Class 2 L-asparaginases belong to the family of Ntn-hydrolases, which are expressed as inactive precursors that must undergo autoproteolytic cleavage into α and β subunits to achieve maturation<ref>PMID:35626629</ref>. While the existence of an alien type of ASNase in the symbiotic nitrogen-fixing bacterium ''Rhizobium etli'' had been recognized long ago<ref>PMID:11996000</ref>, the structure of the inducible and thermolabile prototype Class 3 ReAV was solved and deposited in the PDB only recently<ref>PMID:34795296</ref> ('''Figure ReAV_7os5'''), followed by structures of the constitutive and thermostable isoform ReAIV<ref>PMID:37494066</ref>. More than 200 structures of ASNases have been deposited in the Protein Data Bank (PDB) by April 2024<ref>PMID:34060231</ref> (Wlodawer et al., 2024).