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Figure 2
Structure-based classification of L-asparaginases. Historically, L-asparaginases were named according to the source organism of the first enzymes that were discovered. The new nomenclature divides L-asparaginases into three classes. Cytosolic type 1 enzymes are expressed constitutively, while the expression of type 2 enzymes, which are secreted to the periplasm, is induced under anaerobic conditions in E. coli. In the R. etli-type Class 3, constitutive type 4 enzymes are thermostable, while type 5 enzymes are considered thermolabile and their expression is induced by the presence of L-Asn. Examples of enzymes are listed below the boxes. The organism name abbreviations are as follows: Ec, Esherichia coli; Pf, Pyrococcus furiosus; Ph, Pyrococcus horikoshii; Tk, Thermococcus kodakarensis; Vc, Vibrio cholerae; Yp, Yersinia pestis; Cp, Cavia porcellus; Er, Erwinia chrysanthemi; Ew, Erwinia carotovora; Cj, Campylobacter jejuni; Hp, Helicobacter pylori; Ws, Wolinella succinogenes; Ll, Lupinus luteus; Pv, Phaseolus vulgaris; Hs, Homo sapiens; Re, Rhizobium etli. Examples of PDB codes are summarized in Supplementary Table S1. An asterisk denotes enzymes that are annotated as products of an ansA gene; however, the architecture of the active site and substrate affinity suggest classification as Class 1 type 2 enzymes.

IUCrJ
Volume 8| Part 4| July 2021| Pages 514-531
ISSN: 2052-2525
https://doi.org/10.1107/S2052252521006011