Name	Proposed General Definition	Remarks
Artilysin	Registered name by the company Lysando describing specifically engineered lysins
Catalytic domain (CD)	See “enzymatically active domain”
Cell wall-binding domain (CBD, CWBD)	Domain of an enzyme whose main function is to bind to a cell wall component.
Cell wall-degrading enzyme	See “peptidoglycan-degrading enzyme”
Chimeolysin	See “chimeric lysin”
Chimeric endolysin	See “chimeric lysin”	See remarks to “engineered endolysin”
Chimeric lysin	Engineered lysin whose architecture is the result of fusing modules originating from different proteins
DLA	A term introduced by the company ContraFect, describing antimicrobial agents that act by directly causing lysis of the bacterium.	It may be used to refer to phage lysins or engineered lysins but also to lysin-causing antimicrobial peptides
Domain	Unit of structural, functional and/or sequence conservation within a protein.
Ectolysin	See “structural lysin”
Endolysin	Enzyme encoded by a phage genome that causes bacterial cell lysis at the end of the phage lytic cycle, mainly by catalyzing peptidoglycan degradation, when released towards the cell wall	Should be restricted only to natural phage lysins that exert their action from within the host cell
Endopeptidase	Enzyme that catalyzes the hydrolytic cleavage of peptide bonds, particularly not at the end of a peptide chain.	General EC number for peptidases is 3.4. There are rather generalistic endopeptidases, such as l-alanoyl-d-glutamate endopeptidases, which cleave the peptide stem between two quite conserved amino acids and others that are more specific, such as some interpeptide bridge-specific endopeptidases (e.g., d-alanyl-glycyl endopeptidases, glycyl-glycyl endopeptidases, etc.)
Engineered endolysin	Endolysin that has been modified with respect to its original, wild-type sequence(s)	Conflicting name: since most engineered endolysins are not involved by principle in bacterial lysis from within the cell, “engineered lysin” would be a more etymologically correct term. Only in some specific circumstances “engineered endolysin” may be more accurate.
Engineered lysin	Lysin that has been modified with respect to its original, wild-type sequence(s)
Enzybiotic	Enzyme that works as an antimicrobial agent
Enzymatically active domain (EAD)	Domain of an enzyme whose main function is to catalyze a reaction
EPLE	Engineered phage lytic enzyme, see “engineered lysin”. A name introduced by the company Telum Therapeutics.
Glucosaminidase	Enzyme that catalyzes hydrolysis of terminal non-reducing N-acetyl-d-hexosamine residues. Particularly, among lysins, glucosaminidases break the bond between N-acetyl-d-glucosamine and N-acetyl muramic acid at the reducing side of the former	EC 3.2.1.52, accepted name: β-N-acetylhexosaminidase, full name: N-acetyl-β-d-glucosaminidase
Holin	Protein encoded by a phage genome that forms large pores at the inner membrane of the bacterial host to release endolysins to the cell wall at the end of the phage lytic cycle
Innolysin	Chimeric lysin that is made up of modules originating from a lysin plus a phage receptor-binding protein (RBP)
Lysin	Enzyme that catalytically degrades the cell wall peptidoglycan.	Broad term, could be applied to phage lysins, bacterial lysins, engineered ones, etc.
Lysin A	Enzyme encoded at the genome of a phage infecting diderm bacteria with an arabino-mycolyl outer layer that exerts bacterial host cell lysis by cleaving peptidoglycan bonds	May be just named “endolysin”
Lysin B	Enzyme encoded at the genome of a phage infecting diderm bacteria with an arabino-mycolyl outer layer that exerts bacterial host cell lysis by cleaving arabino-mycolyl ester bonds
Lysocin	Chimeric lysin that is made up of modules originating from a lysin and bacteriocin elements responsible for surface receptor-binding and outer membrane translocation	Conflicting name: a class of antibiotics is already called “lysocins”
Lysozyme	Enzyme that hydrolytically cleaves the 1,4-β-linkages between N-acetylmuramic acid and N-acetyl-d-glucosamine residues in peptidoglycan (and between two N-acetyl-d-glucosamine residues in chitodextrins)	EC 3.2.1.17
Lytic transglycosylase	Enzyme that catalyzes non-hydrolytic cleavage of the bond between N-acetyl-d-glucosamine and N-acetyl muramic acid through a process in which a sugar molecule is transformed into another (an anhydro derivative)	EC 4.2.2.n (still not definitive EC number). Alternative name: muropeptide lyase
Module	Structural and functional element from a protein (or other composite entity) that is interchangeable or susceptible to be integrated into another higher-order unit
Muralysin	See “peptidoglycan-degrading enzyme”
Muralytic enzyme	See “peptidoglycan-degrading enzyme”
Muramidase	See “lysozyme”	Full name: 1,4-β-N-acetylmuramidase
Murein hydrolase	See “peptidoglycan hydrolase”
N-acetylmuramoyl (NAM-)amidase	Enzyme that catalyzes hydrolytic cleavage of the bond between N-acetylmuramoyl and an l-amino acid residue of the stem peptide of the peptidoglycan	EC 3.5.1.28, full name: N-acetylmuramoyl-l-alanine amidase
OMP	“Outer membrane permeabilizing”, typically a peptide able to interact and permeabilize biological membranes and, in particular, the outer membrane of Gram-negative bacteria
Peptidase	See “endopeptidase”	The lack of the prefix “endo-” implies that the site of cleavage (terminus or internal site) is not specified. IUBMB does not recommend the term “peptidase”, thus “endopeptidase” is preferred in the context of phage lysins
Peptidoglycan hydrolase (PGH)	Enzyme that catalyzes the hydrolytic cleavage of bonds within the peptidoglycan	Not equivalent to “peptidoglycan-degrading enzyme” since there are peptidoglycan lyases (e.g., lytic transglycosylases)
Peptidoglycan-degrading enzyme	Enzyme that catalyzes the cleavage of bonds within the peptidoglycan	Not restricted to phage lysins, e.g., peptidoglycan recycling/remodeling enzymes or autolysins from bacterial origin are peptidoglycan-degrading enzymes as well
Phage depolymerase	Protein encoded by a phage genome that catalyzes the cleavage of bonds within the exopolysaccharides produced by some bacterial hosts thus facilitating subsequent infection by the virion particles	Not fully distinguished from phage lysins in very early literature
(Phage) exopolysaccharide depolymerase	See “phage depolymerase”
Phage lysin	Enzyme encoded by a phage genome that catalytically degrades the cell wall peptidoglycan	Denoting phage origin should be preferred to avoid ambiguities (thus “phage lysin” should be preferred over just “lysin” when referring to lysins from phages)
Phage lytic enzyme	See “phage lysin”
Phage lytic protein	Protein encoded by a phage genome that catalytically degrades the cell wall peptidoglycan or that noncatalytically exerts bacterial cell lysis	Can potentially be applied both to (endo)lysins, structural lysins -both enzymes- and the rest of nonenzymatic lysis actors (holins, spanins…)
Pinholin	Protein encoded by a phage genome that forms small pores at the inner membrane of the bacterial host cell to allow the activation of signal-arrest-release (SAR-)endolysins
Releasin	Protein encoded by a phage genome that allows release and activation of a SAR-endolysin by a mechanism other than that of pinholins
Spanin	Protein encoded at the genome of a phage infecting diderm, Gram-negative bacteria whose function is to span the periplasm allowing the physical contact of inner and outer membrane to form large pores and then produce the efficient lysis of the bacterial cell host at the end of the lytic cycle
Structural lysin	Enzyme encoded by a phage genome that catalyzes the cleavage of peptidoglycan and is present within the virion particle
Tail-associated lysin (TAL)	See “structural lysin”
Tail-associated muralytic enzyme (TAME)	See “structural lysin”
Virion-associated lysin	See “structural lysin”
Virion-associated peptidoglycan hydrolase (VAPGH, VAPH)	Enzyme encoded by a phage genome that catalyzes the hydrolytic cleavage of peptidoglycan bonds and is present within the virion particle	Does not include all structural lysins (since some of them are potentially lyases and not hydrolases)