The main components of oral malodour have been identified as volatile sulfur compounds (VSCs), including hydrogen sulfide (H2S) and methyl mercaptan (CH3SH). The lactoperoxidase (LPO) system (consisting of LPO, glucose oxidase, glucose and thiocyanate) was previously shown to exhibit antimicrobial activities against some oral bacteria in vitro and suppressive effects on VSCs in mouth air in a clinical trial. Here, we examined the in vitro effects of the LPO system on the activities of the bacterial lyases involved in the production of VSCs by oral anaerobes. The exposure of crude bacterial extracts of Fusobacterium nucleatum and Porphyromonas gingivalis or purified methionine γ-lyase to the LPO system resulted in the inactivation of their lyase activities through l-cysteine and l-methionine, which was linked to the production of H2S and CH3SH, respectively. The exposure of living F. nucleatum and P. gingivalis cells to the LPO system resulted in the suppression of cell numbers and lyase activities. The inactivation of the crude bacterial extracts of F. nucleatum and purified methionine γ-lyase by the LPO system was partly recovered by the addition of DTT. Therefore, the LPO system may inactivate bacterial lyases including methionine γ-lyase by reacting with the free cysteine residues of lyases. These results suggested that the LPO system suppresses the production of VSCs not only through its antimicrobial effects, but also by its inactivating effects on the bacterial lyases of F. nucleatum and P. gingivalis.
CourtoisP.,
MajerusP.,
LabbéM.,
Vanden AbbeeleA.,
YourassowskyE.,
PourtoisM.1992; Susceptibility of anaerobic microorganisms to hypothiocyanite produced by lactoperoxidase. Acta Stomatol Belg 89:155–162[PubMed]
FukamachiH.,
NakanoY.,
YoshimuraM.,
KogaT.2002; Cloning and characterization of the l-cysteine desulfhydrase gene of Fusobacterium nucleatum
. FEMS Microbiol Lett 215:75–80[PubMed]
HamonC. B.,
KlebanoffS. J.1973; A peroxidase-mediated, Streptococcus mitis-dependent antimicrobial system in saliva. J Exp Med 137:438–450 [View Article][PubMed]
IhalinR.,
LoimarantaV.,
Lenander-LumikariM.,
TenovuoJ.2001; The sensitivity of Porphyromonas gingivalis and Fusobacterium nucleatum to different (pseudo)halide-peroxidase combinations compared with mutans streptococci. J Med Microbiol 50:42–48[PubMed][CrossRef]
JohnsonP.,
YaegakiK.,
TonzetichJ.1996; Effect of methyl mercaptan on synthesis and degradation of collagen. J Periodontal Res 31:323–329 [View Article][PubMed]
KudouD.,
MisakiS.,
YamashitaM.,
TamuraT.,
TakakuraT.,
YoshiokaT.,
YagiS.,
HoffmanR. M.,
TakimotoA.,
other authors.
2007; Structure of the antitumour enzyme l-methionine γ-lyase from Pseudomonas putida at 1.8 A resolution. J Biochem 141:535–544 [View Article][PubMed]
KudouD.,
MisakiS.,
YamashitaM.,
TamuraT.,
EsakiN.,
InagakiK.2008; The role of cysteine 116 in the active site of the antitumor enzyme l-methionine γ-lyase from Pseudomonas putida
. Biosci Biotechnol Biochem 72:1722–1730 [View Article][PubMed]
LawB. A.,
JohnP.1981; Effect of the lactoperoxidase bactericidal system on the formation of the electrochemical proton gradient in E. coli
. FEMS Microbiol Lett 10:67–70 [View Article]
MickelsonM. N.1977; Glucose transport in Streptococcus agalactiae and its inhibition by lactoperoxidase-thiocyanate-hydrogen peroxide. J Bacteriol 132:541–548[PubMed]
NgW.,
TonzetichJ.1984; Effect of hydrogen sulfide and methyl mercaptan on the permeability of oral mucosa. J Dent Res 63:994–997 [View Article][PubMed]
PruittK. M.,
Mansson-RahemtullaB.,
TenovuoJ.1983; Detection of the hypothiocyanite (OSCN-) ion in human parotid saliva and the effect of pH on OSCN- generation in the salivary peroxidase antimicrobial system. Arch Oral Biol 28:517–525 [View Article][PubMed]
ShinK.,
YamauchiK.,
TeraguchiS.,
HayasawaH.,
ImotoI.2002; Susceptibility of Helicobacter pylori and its urease activity to the peroxidase-hydrogen peroxide-thiocyanate antimicrobial system. J Med Microbiol 51:231–237[PubMed][CrossRef]
ShinK.,
HorigomeA.,
WakabayashiH.,
YamauchiK.,
YaeshimaT.,
IwatsukiK.2008; In vitro and in vivo effects of a composition containing lactoperoxidase on oral bacteria and breath odor. J Breath Res 2:017014[CrossRef]
SuwabeK.,
YoshidaY.,
NaganoK.,
YoshimuraF.2011; Identification of an l-methionine γ-lyase involved in the production of hydrogen sulfide from l-cysteine in Fusobacterium nucleatum subsp. nucleatum ATCC 25586. Microbiology 157:2992–3000 [View Article][PubMed]
TenovuoJ.,
MäkinenK. K.,
SieversG.1985; Antibacterial effect of lactoperoxidase and myeloperoxidase against Bacillus cereus
. Antimicrob Agents Chemother 27:96–101 [View Article][PubMed]
ThomasE. L.1981; Lactoperoxidase-catalyzed oxidation of thiocyanate: equilibria between oxidized forms of thiocyanate. Biochemistry 20:3273–3280 [View Article][PubMed]
ThomasE. L.,
PeraK. A.,
SmithK. W.,
ChwangA. K.1983; Inhibition of Streptococcus mutans by the lactoperoxidase antimicrobial system. Infect Immun 39:767–778[PubMed]
ThomasE. L.,
BozemanP. M.,
LearnD. B.1991; Lactoperoxidase: structure and catalytic properties. In Peroxidases in Chemistry and Biology, vol. 1 pp. 123–142 Edited by
GrishamM. B.,
EverseJ.
Boca Raton, FL: CRC Press;