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MicroCorrespondence
On the misuse of the term ‘lysozyme’
Sir,
Lysozymes (EC 3.2.1.17) (alternative name: murami-dases) are defined as enzymes that catalyse the hydroly-sis of the 1,4-b-linkages between N-acetyl-D-glucosamineand N-acetylmuramic acid in the peptidoglycan of prokar-yotic cell walls. On the other hand, enzymes that hydrolysethe link between N-acetylmuramoyl residues and L-aminoacid residues in peptidoglycans are named N-acetylmura-moyl-L-alanine amidases (EC 3.5.1.28) and alternativenames are not accepted. Taking into account these defini-tions, it is surprising how frequently the correspondingterms are misused in the scientific literature. As a paradig-matic illustration of inaccuracy, the protein encoded bythe gene 3.5 of bacteriophage T7 is universally designatedas the ‘T7 lysozyme’ even in prestigious and scrupulousjournals (Chen et al., 1994, Proc Natl Acad Sci USA 91:4034–4038; Zhang and Studier, 1995, J Mol Biol 250:156–168; Bartel et al., 1996, Nature Genet 12: 72–77,and references therein) although it was clearly estab-lished, more than 20 years ago, that this protein is an N-acetylmuramoyl-L-alanine amidase rather than a murami-dase (Inouye et al., 1973, J Biol Chem 248: 7247–7252).
Some databases also contain important mistakes.Thus, the lysozymes encoded by the pneumococcal
phages of the Cp family (Garcıa et al., 1987, J Virol 61:2573–2580; Garcıa et al., 1990, Gene 86: 81–88) aresimultaneously designated as N-acetylmuramoyl-L-alanineamidases and muramidases in the SWISSPROT (acces-sion numbers P15057, P19385, and P19386) and PRO-SITE (PDOC00737) data banks. This error has led to asignificant mistake since, in the later database, it is statedthat ‘lysozymes and N-acetylmuramoyl-L-alanine ami-dases are evolutionarily related and can be classifiedinto a single family’. It should be mentioned that repeatedattempts to correct the corresponding files of the SWIS-SPROT database have been unsuccessful to date.
As one of the characteristics of science is the use ofspecialized terms to define concepts, phenomena,objects, etc. as accurately as possible, it should be impera-tive that editors and referees guarantee the correct use ofthe technical terminology to avoid cases similar to the onedescribed here.
Ernesto GarcıaDepartamento de Microbiologıa Molecular, Centro deInvestigaciones Biologicas, Consejo Superior deInvestigaciones Cientıficas, 28006 Madrid, Spain.E-mail [email protected]; Tel. (1) 5611800; Fax (1)5627518.Received 13 May, 1996; revised 25 May, 1996; accepted30 May, 1996.
Molecular Microbiology (1996) 21(4), 885
# 1996 Blackwell Science Ltd
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