Lysozyme

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Lysozyme
Identifiers
EC no. 3.2.1.17
CAS no. 9001-63-2
Databases
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BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
Gene Ontology AmiGO / QuickGO
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PMC articles
PubMed articles
NCBI proteins
Glycoside hydrolase, family 22, lysozyme
Lysozymecrystals1.png
Lysozyme crystals stained with methylene blue.
Identifiers
Symbol?
InterPro IPR000974

Lysozyme (EC 3.2.1.17, muramidase, N-acetylmuramide glycanhydrolase; systematic name peptidoglycan N-acetylmuramoylhydrolase) is an antimicrobial enzyme produced by animals that forms part of the innate immune system. It is a glycoside hydrolase that catalyzes the following process:

Contents

Hydrolysis of (1→4)-β-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in a peptidoglycan and between N-acetyl-D-glucosamine residues in chitodextrins

Peptidoglycan is the major component of gram-positive bacterial cell wall. [1] This hydrolysis in turn compromises the integrity of bacterial cell walls causing lysis of the bacteria.

Lysozyme is abundant in secretions including tears, saliva, human milk, and mucus. It is also present in cytoplasmic granules of the macrophages and the polymorphonuclear neutrophils (PMNs). Large amounts of lysozyme can be found in egg white. C-type lysozymes are closely related to α-lactalbumin in sequence and structure, making them part of the same glycoside hydrolase family 22. [2] In humans, the C-type lysozyme enzyme is encoded by the LYZ gene. [3] [4]

Hen egg white lysozyme is thermally stable, with a melting point reaching up to 72 °C at pH 5.0. [5] However, lysozyme in human milk loses activity very quickly at that temperature. [6] Hen egg white lysozyme maintains its activity in a large range of pH (6–9). [7] Its isoelectric point is 11.35. [8] The isoelectric point of human milk lysozyme is 10.5–11. [9]

Function and mechanism

The enzyme functions by hydrolyzing glycosidic bonds in peptidoglycans. The enzyme can also break glycosidic bonds in chitin, although not as effectively as true chitinases. [10]

Overview of the reaction catalysed by lysozyme Mecanism of action for Lysozyme.svg
Overview of the reaction catalysed by lysozyme

Lysozyme's active site binds the peptidoglycan molecule in the prominent cleft between its two domains. It attacks peptidoglycans (found in the cell walls of bacteria, especially Gram-positive bacteria), its natural substrate, between N-acetylmuramic acid (NAM) and the fourth carbon atom of N-acetylglucosamine (NAG).[ citation needed ]

Shorter saccharides like tetrasaccharide have also shown to be viable substrates but via an intermediate with a longer chain. [11] Chitin has also been shown to be a viable lysozyme substrate. Artificial substrates have also been developed and used in lysozyme. [12]

Mechanism

Phillips

The Phillips mechanism proposed that the enzyme's catalytic power came from both steric strain on the bound substrate and electrostatic stabilization of an oxo-carbenium intermediate. From X-ray crystallographic data, Phillips proposed the active site of the enzyme, where a hexasaccharide binds. The lysozyme distorts the fourth sugar (in the D or -1 subsite) in the hexasaccharide into a half-chair conformation. In this stressed state, the glycosidic bond is more easily broken. [13] An ionic intermediate containing an oxo-carbenium is created as a result of the glycosidic bond breaking. [14] Thus distortion causing the substrate molecule to adopt a strained conformation similar to that of the transition state will lower the energy barrier of the reaction. [15]

The proposed oxo-carbonium intermediate was speculated to be electrostatically stabilized by aspartate and glutamate residues in the active site by Arieh Warshel in 1978. The electrostatic stabilization argument was based on comparison to bulk water, the reorientation of water dipoles can cancel out the stabilizing energy of charge interaction. In Warshel's model, the enzyme acts as a super-solvent, which fixes the orientation of ion pairs and provides super-solvation (very good stabilization of ion pairs), and especially lower the energy when two ions are close to each other. [16]

The rate-determining step (RDS) in this mechanism is related to formation of the oxo-carbenium intermediate. There were some contradictory results to indicate the exact RDS. By tracing the formation of product (p-nitrophenol), it was discovered that the RDS can change over different temperatures, which was a reason for those contradictory results. At a higher temperature the RDS is formation of glycosyl enzyme intermediate and at a lower temperature the breakdown of that intermediate. [17]

Covalent intermediate of lysozyme enzyme, with covalent bond in black and experimental evidence as blue mesh. Lysozyme glycosyl covalent intermediate.gif
Covalent intermediate of lysozyme enzyme, with covalent bond in black and experimental evidence as blue mesh.

Covalent mechanism

Substrates in Vocadlo's experiment LysozymeIntermediates copy.png
Substrates in Vocadlo's experiment

In an early debate in 1969, Dahlquist proposed a covalent mechanism for lysozyme based on kinetic isotope effect, [14] but for a long time the ionic mechanism was more accepted. In 2001, a revised mechanism was proposed by Vocadlo via a covalent but not ionic intermediate. Evidence from ESI-MS analysis indicated a covalent intermediate. A 2-fluoro substituted substrate was used to lower the reaction rate and accumulate an intermediate for characterization. [19] The amino acid side-chains glutamic acid 35 (Glu35) and aspartate 52 (Asp52) have been found to be critical to the activity of this enzyme. Glu35 acts as a proton donor to the glycosidic bond, cleaving the C-O bond in the substrate, whereas Asp52 acts as a nucleophile to generate a glycosyl enzyme intermediate. The Glu35 reacts with water to form hydroxyl ion, a stronger nucleophile than water, which then attacks the glycosyl enzyme intermediate, to give the product of hydrolysis and leaving the enzyme unchanged. [20] This type of covalent mechanism for enzyme catalysis was first proposed by Koshland. [21]

More recently, quantum mechanics/ molecular mechanics (QM/MM) molecular dynamics simulations have been using the crystal of HEWL and predict the existence of a covalent intermediate. [22] Evidence for the ESI-MS and X-ray structures indicate the existence of covalent intermediate, but primarily rely on using a less active mutant or non-native substrate. Thus, QM/MM molecular dynamics provides the unique ability to directly investigate the mechanism of wild-type HEWL and native substrate. The calculations revealed that the covalent intermediate from the covalent mechanism is ~30 kcal/mol more stable than the ionic intermediate from the Phillips mechanism. [22] These calculations demonstrate that the ionic intermediate is extremely energetically unfavorable and the covalent intermediates observed from experiments using less active mutant or non-native substrates provide useful insight into the mechanism of wild-type HEWL.[ citation needed ]

Two Possible Mechanisms of Lysozyme JBSlysozymemechanism copy2.jpg
Two Possible Mechanisms of Lysozyme

Inhibition

Imidazole derivatives can form a charge-transfer complex with some residues (in or outside active center) to achieve a competitive inhibition of lysozyme. [23] In Gram-negative bacteria, the lipopolysaccharide acts as a non-competitive inhibitor by highly favored binding with lysozyme. [24]

Non-enzymatic action

Despite that the muramidase activity of lysozyme has been supposed to play the key role for its antibacterial properties, evidence of its non-enzymatic action was also reported. For example, blocking the catalytic activity of lysozyme by mutation of critical amino acid in the active site (52-Asp -> 52-Ser) does not eliminate its antimicrobial activity. [25] The lectin-like ability of lysozyme to recognize bacterial carbohydrate antigen without lytic activity was reported for tetrasaccharide related to lipopolysaccharide of Klebsiella pneumoniae . [26] Also, lysozyme interacts with antibodies and T-cell receptors. [27]

Enzyme conformation changes

Lysozyme exhibits two conformations: an open active state and a closed inactive state. The catalytic relevance was examined with single walled carbon nanotubes (SWCN) field effect transistors (FETs), where a singular lysozyme was bound to the SWCN FET. [28] Electronically monitoring the lysozyme showed two conformations, an open active site and a closed inactive site. In its active state lysozyme is able to processively hydrolyze its substrate, breaking on average 100 bonds at a rate of 15 per second. In order to bind a new substrate and move from the closed inactive state to the open active state requires two conformation step changes, while inactivation requires one step.[ citation needed ]

Superfamily

The conventional C-type lysozyme is part of a larger group of structurally and mechanistically related enzymes termed the lysozyme superfamily . This family unites GH22 C-type ("chicken") lysozymes with plant chitinase GH19, G-type ("goose") lysozyme GH23, V-type ("viral") lysozyme GH24 and the chitosanase GH46 families. The lysozyme-type nomenclature only reflects the source a type is originally isolated from and does not fully reflect the taxonomic distribution. [29] For example, humans and many other mammals have two G-type lysozyme genes, LYG1 and LYG2. [30]

Role in disease and therapy

LYZ
Available structures
PDB Ortholog search: PDBe RCSB
Identifiers
Aliases LYZ , LZM, LYZF1, lysozyme
External IDs OMIM: 153450; MGI: 96902; HomoloGene: 121490; GeneCards: LYZ; OMA:LYZ - orthologs
Orthologs
SpeciesHumanMouse
Entrez

4069

17110

Ensembl

ENSG00000090382

ENSMUSG00000069515

UniProt

P61626

P17897

RefSeq (mRNA)

NM_000239

NM_013590

RefSeq (protein)

NP_000230

NP_038618

Location (UCSC) Chr 12: 69.35 – 69.35 Mb Chr 10: 117.12 – 117.13 Mb
PubMed search [33] [34]
Wikidata
View/Edit Human View/Edit Mouse

Lysozyme is part of the innate immune system. Reduced lysozyme levels have been associated with bronchopulmonary dysplasia in newborns. [35] Piglets fed with human lysozyme milk can recover from diarrheal disease caused by E. coli faster. The concentration of lysozyme in human milk is 1,600 to 3,000 times greater than the concentration in livestock milk. Human lysozyme is more active than hen egg white lysozyme. A transgenic line of goats (with a founder named "Artemis") were developed to produce milk with human lysozyme to protect children from diarrhea if they can't get the benefits of human breastfeeding. [36] [37]

Since lysozyme is a natural form of protection from Gram-positive pathogens like Bacillus and Streptococcus , [38] it plays an important role in immunology of infants in human milk feeding. [39] Whereas the skin is a protective barrier due to its dryness and acidity, the conjunctiva (membrane covering the eye) is, instead, protected by secreted enzymes, mainly lysozyme and defensin. However, when these protective barriers fail, conjunctivitis results.[ citation needed ]

In certain cancers (especially myelomonocytic leukemia) excessive production of lysozyme by cancer cells can lead to toxic levels of lysozyme in the blood. High lysozyme blood levels can lead to kidney failure and low blood potassium, conditions that may improve or resolve with treatment of the primary malignancy.[ citation needed ]

Serum lysozyme is much less specific for diagnosis of sarcoidosis than serum angiotensin converting enzyme; however, since it is more sensitive, it is used as a marker of sarcoidosis disease activity and is suitable for disease monitoring in proven cases. [40]

Chemical synthesis

The first chemical synthesis of a lysozyme protein was attempted by Prof. George W. Kenner and his group at the University of Liverpool in England. [41] This was finally achieved in 2007 by Thomas Durek in Steve Kent's lab at the University of Chicago who made a synthetic functional lysozyme molecule. [42]

Other applications

Lysozyme crystals have been used to grow other functional materials for catalysis and biomedical applications. [43] [44] [45] Lysozyme is a commonly used enzyme for lysing gram positive bacteria. [46] Due to the unique function of lysozyme in which it can digest the cell wall and causes osmotic shock (burst the cell by suddenly changing solute concentration around the cell and thus the osmotic pressure), lysozyme is commonly used in lab setting to release proteins from bacterium periplasm while the inner membrane remains sealed as vesicles called the spheroplast. [47] [48]

For example, E. coli can be lysed using lysozyme to free the contents of the periplasmic space. It is especially useful in lab setting for trying to collect the contents of the periplasm. [1] Lysozyme treatment is optimal at particular temperatures, pH ranges, and salt concentrations. Lysozyme activity increases with increasing temperatures, up to 60 degrees Celsius, with a pH range of 6.0-7.0. The salts present also affect lysozyme treatment, where some assert inhibitory effects, and others promote lysis via lysozyme treatment. Sodium chloride induces lysis, but at high concentrations, it is an active inhibitor of lysis. Similar observations have been seen with the use of potassium salts. Slight variations are present due to differences in bacterial strains. [49] A consequence of the use of lysozyme in extracting recombinant proteins for protein crystallization is that the crystal may be contaminated with units of lysozyme, producing a physiologically irrelevant combination. In fact, some proteins simply cannot crystalize without such contamination. [50] [51]

Furthermore, lysozyme can serve as a tool in the expression of toxic recombinant proteins. Expressing recombinant proteins in BL21(DE3) strains is typically accomplished by the T7-RNA-polymerase. Via IPTG induction, the UV-5 repressor is inhibited, leading to the transcription of the T7-RNA-polymerase and thereby of the protein of interest. Nonetheless, a basal level of the T7-RNA-polymerase is observable even without induction. T7 lysozyme acts as an inhibitor of the T7-RNA-polymerase. Newly invented strains, containing a helper plasmid (pLysS), constitutively co-express low levels of T7 lysozyme, providing high stringency and consistent expression of the toxic recombinant protein. [52]

History

The antibacterial property of hen egg white, due to the lysozyme it contains, was first observed by Laschtschenko in 1909. [53] The bacteria-killing activity of nasal mucus was demonstrated in 1922 by Alexander Fleming, the discoverer of penicillin, who coined the term "lysozyme". [54] He is reported as saying: "As this substance has properties akin to those of ferments I have called it a 'Lysozyme'." [55] Fleming went on to show that an enzymic substance was present in a wide variety of secretions and was capable of rapidly lysing (i.e. dissolving) different bacteria, particularly a yellow "coccus" that he studied". [56]

Lysozyme was first crystallised by Edward Abraham in 1937, enabling the three-dimensional structure of hen egg white lysozyme to be described by David Chilton Phillips in 1965, when he obtained the first 2-ångström (200 pm) resolution model via X-ray crystallography. [57] [58] The structure was publicly presented at a Royal Institution lecture in 1965. [59] Lysozyme was the second protein structure and the first enzyme structure to be solved via X-ray diffraction methods, and the first enzyme to be fully sequenced that contains all twenty common amino acids. [60] As a result of Phillips' elucidation of the structure of lysozyme, it was also the first enzyme to have a detailed, specific mechanism suggested for its method of catalytic action. [61] [62] [63] This work led Phillips to provide an explanation for how enzymes speed up a chemical reaction in terms of its physical structures. The original mechanism proposed by Phillips was more recently revised. [19]

See also

Related Research Articles

<span class="mw-page-title-main">Enzyme</span> Large biological molecule that acts as a catalyst

Enzymes are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called enzymology and the field of pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties.

Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like layer (sacculus) that surrounds the bacterial cytoplasmic membrane. The sugar component consists of alternating residues of β-(1,4) linked N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM). Attached to the N-acetylmuramic acid is an oligopeptide chain made of three to five amino acids. The peptide chain can be cross-linked to the peptide chain of another strand forming the 3D mesh-like layer. Peptidoglycan serves a structural role in the bacterial cell wall, giving structural strength, as well as counteracting the osmotic pressure of the cytoplasm. This repetitive linking results in a dense peptidoglycan layer which is critical for maintaining cell form and withstanding high osmotic pressures, and it is regularly replaced by peptidoglycan production. Peptidoglycan hydrolysis and synthesis are two processes that must occur in order for cells to grow and multiply, a technique carried out in three stages: clipping of current material, insertion of new material, and re-crosslinking of existing material to new material.

β-Galactosidase Family of glycoside hydrolase enzymes

β-Galactosidase is a glycoside hydrolase enzyme that catalyzes hydrolysis of terminal non-reducing β-D-galactose residues in β-D-galactosides.

A glycosidic bond or glycosidic linkage is a type of ether bond that joins a carbohydrate (sugar) molecule to another group, which may or may not be another carbohydrate.

An Endoglycosidase is an enzyme that releases oligosaccharides from glycoproteins or glycolipids. It may also cleave polysaccharide chains between residues that are not the terminal residue, although releasing oligosaccharides from conjugated protein and lipid molecules is more common.

<span class="mw-page-title-main">Pseudopeptidoglycan</span>

Pseudopeptidoglycan is a major cell wall component of some Archaea that differs from bacterial peptidoglycan in chemical structure, but resembles bacterial peptidoglycan in function and physical structure. Pseudopeptidoglycan, in general, is only present in a few methanogenic archaea. The basic components are N-acetylglucosamine and N-acetyltalosaminuronic acid, which are linked by β-1,3-glycosidic bonds.

<span class="mw-page-title-main">Glucocerebrosidase</span> Mammalian protein found in humans

β-Glucocerebrosidase is an enzyme with glucosylceramidase activity that cleaves by hydrolysis the β-glycosidic linkage of the chemical glucocerebroside, an intermediate in glycolipid metabolism that is abundant in cell membranes. It is localized in the lysosome, where it remains associated with the lysosomal membrane. β-Glucocerebrosidase is 497 amino acids in length and has a molecular mass of 59,700 Da.

A bacterium, despite its simplicity, contains a well-developed cell structure which is responsible for some of its unique biological structures and pathogenicity. Many structural features are unique to bacteria and are not found among archaea or eukaryotes. Because of the simplicity of bacteria relative to larger organisms and the ease with which they can be manipulated experimentally, the cell structure of bacteria has been well studied, revealing many biochemical principles that have been subsequently applied to other organisms.

<span class="mw-page-title-main">Glycoside hydrolase</span> Class of enzymes which break glycosidic bonds via hydrolysis

In biochemistry, glycoside hydrolases are a class of enzymes which catalyze the hydrolysis of glycosidic bonds in complex sugars. They are extremely common enzymes, with roles in nature including degradation of biomass such as cellulose (cellulase), hemicellulose, and starch (amylase), in anti-bacterial defense strategies, in pathogenesis mechanisms and in normal cellular function. Together with glycosyltransferases, glycosidases form the major catalytic machinery for the synthesis and breakage of glycosidic bonds.

<span class="mw-page-title-main">Lysin</span>

Lysins, also known as endolysins or murein hydrolases, are hydrolytic enzymes produced by bacteriophages in order to cleave the host's cell wall during the final stage of the lytic cycle. Lysins are highly evolved enzymes that are able to target one of the five bonds in peptidoglycan (murein), the main component of bacterial cell walls, which allows the release of progeny virions from the lysed cell. Cell-wall-containing Archaea are also lysed by specialized pseudomurein-cleaving lysins, while most archaeal viruses employ alternative mechanisms. Similarly, not all bacteriophages synthesize lysins: some small single-stranded DNA and RNA phages produce membrane proteins that activate the host's autolytic mechanisms such as autolysins.

<span class="mw-page-title-main">Lactoperoxidase</span> Mammalian protein found in Homo sapiens

Lactoperoxidase is a peroxidase enzyme secreted from mammary, salivary and other mucosal glands including the lungs, bronchii and nose that functions as a natural and the first line of defense against bacteria and viruses. Lactoperoxidase is a member of the heme peroxidase family of enzymes. In humans, lactoperoxidase is encoded by the LPO gene.

<span class="mw-page-title-main">Glucansucrase</span> Enzyme

Glucansucrase is an enzyme in the glycoside hydrolase family GH70 used by lactic acid bacteria to split sucrose; it then utilizes the resulting glucose molecules to build long, sticky biofilm chains. These extracellular homopolysaccharides are called α-glucan polymers.

In molecular biology, glycoside hydrolase family 22 is a family of glycoside hydrolases. EC 3.2.1., which are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A classification system for glycoside hydrolases, based on sequence similarity, has led to the definition of >100 different families. This classification is available on the CAZy web site, and also discussed at CAZypedia, an online encyclopedia of carbohydrate active enzymes.

<span class="mw-page-title-main">Glycoside hydrolase family 24</span>

In molecular biology, glycoside hydrolase family 24 is a family of glycoside hydrolases.

In molecular biology, glycoside hydrolase family 108 is a family of glycoside hydrolases.

<span class="mw-page-title-main">Glucanase</span>

Glucanases are enzymes that break down large polysaccharides via hydrolysis. The product of the hydrolysis reaction is called a glucan, a linear polysaccharide made of up to 1200 glucose monomers, held together with glycosidic bonds. Glucans are abundant in the endosperm cell walls of cereals such as barley, rye, sorghum, rice, and wheat. Glucanases are also referred to as lichenases, hydrolases, glycosidases, glycosyl hydrolases, and/or laminarinases. Many types of glucanases share similar amino acid sequences but vastly different substrates. Of the known endo-glucanases, 1,3-1,4-β-glucanase is considered the most active.

Sortases are membrane anchored enzyme that sort these surface proteins onto the bacterial cell surface and anchor them to the peptidoglycan. There are different types of sortases and each catalyse the anchoring of different proteins to cell walls.

<span class="mw-page-title-main">Gideon Davies</span> Professor of Chemistry

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<span class="mw-page-title-main">OBPgp279</span>

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References

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  2. ↑ Williams S, Vocadlo D. "Glycoside hydrolase family 22". Cazypedia. Retrieved 11 April 2017.
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  5. ↑ Venkataramani S, Truntzer J, Coleman DR (April 2013). "Thermal stability of high concentration lysozyme across varying pH: A Fourier Transform Infrared study". Journal of Pharmacy & Bioallied Sciences. 5 (2): 148–153. doi: 10.4103/0975-7406.111821 . PMC   3697194 . PMID   23833521.
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  7. ↑ "Lysozyme, Product information" (PDF). Sigma-Aldrich.
  8. ↑ "Lysozyme, Product information" (PDF). Sigma-Aldrich.
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  10. ↑ Skujiņś J, Puķite A, McLaren AD (December 1973). "Adsorption and reactions of chitinase and lysozyme on chitin". Molecular and Cellular Biochemistry. 2 (2): 221–228. doi:10.1007/BF01795475. PMID   4359167. S2CID   27906558.
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  12. ↑ Höltje JV (1 January 1996). "Lysozyme Substrates". Lysozymes: Model Enzymes in Biochemistry and Biology. Experientia Supplementum. Vol. 75. pp. 105–110. doi:10.1007/978-3-0348-9225-4_7 (inactive 2 November 2024). ISBN   978-3-0348-9952-9. PMID   8765297.{{cite book}}: CS1 maint: DOI inactive as of November 2024 (link)
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  15. ↑ McKenzie HA, White FH (1991). "Lysozyme and α-lactalbumin: structure, function, and interrelationships". Advances in Protein Chemistry. 41: 173–315. doi:10.1016/s0065-3233(08)60198-9. ISBN   978-0-12-034241-9. PMID   2069076.
  16. ↑ Warshel A (November 1978). "Energetics of enzyme catalysis". Proceedings of the National Academy of Sciences of the United States of America. 75 (11): 5250–5254. Bibcode:1978PNAS...75.5250W. doi: 10.1073/pnas.75.11.5250 . PMC   392938 . PMID   281676.
  17. ↑ Weber JP, Fink AL (October 1980). "Temperature-dependent change in the rate-limiting step of β-glucosidase catalysis". The Journal of Biological Chemistry. 255 (19): 9030–9032. doi: 10.1016/S0021-9258(19)70521-3 . PMID   6773958.
  18. ↑ "Hen Egg-White (HEW) Lysozyme - Proteopedia, life in 3D".
  19. 1 2 Vocadlo DJ, Davies GJ, Laine R, Withers SG (August 2001). "Catalysis by hen egg-white lysozyme proceeds via a covalent intermediate" (PDF). Nature. 412 (6849): 835–838. Bibcode:2001Natur.412..835V. doi:10.1038/35090602. PMID   11518970. S2CID   205020153.
  20. ↑ Grisham CM, Garrett RH (2007). "Chapter 14: Mechanism of enzyme action". Biochemistry. Australia: Thomson Brooks/Cole. pp. 467–9. ISBN   978-0-495-11912-8.
  21. ↑ Koshland DE (November 1953). "Stereochemistry and the Mechanism of Enzymatic Reactions". Biological Reviews. 28 (4): 416–436. doi:10.1111/j.1469-185X.1953.tb01386.x. S2CID   86709302.
  22. 1 2 Bowman AL, Grant IM, Mulholland AJ (October 2008). "QM/MM simulations predict a covalent intermediate in the hen egg white lysozyme reaction with its natural substrate". Chemical Communications (37): 4425–4427. doi:10.1039/b810099c. PMID   18802578.
  23. ↑ Swan ID (March 1972). "The inhibition of hen egg-white lysozyme by imidazole and indole derivatives". Journal of Molecular Biology. 65 (1): 59–62. doi:10.1016/0022-2836(72)90491-3. PMID   5063023.
  24. ↑ Ohno N, Morrison DC (March 1989). "Lipopolysaccharide interaction with lysozyme. Binding of lipopolysaccharide to lysozyme and inhibition of lysozyme enzymatic activity". The Journal of Biological Chemistry. 264 (8): 4434–4441. doi: 10.1016/S0021-9258(18)83761-9 . PMID   2647736.
  25. ↑ Ibrahim HR, Matsuzaki T, Aoki T (September 2001). "Genetic evidence that antibacterial activity of lysozyme is independent of its catalytic function". FEBS Letters. 506 (1): 27–32. Bibcode:2001FEBSL.506...27I. doi: 10.1016/S0014-5793(01)02872-1 . PMID   11591365. S2CID   21593262.
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