Fukamachi Haruka, Nakano Yoshio, Okano Soichiro, Shibata Yasuko, Abiko Yoshimitsu, Yamashita Yoshihisa
Department of Preventive Dentistry, Kyushu University Faculty of Dental Science, Fukuoka 812-8582, Japan.
Biochem Biophys Res Commun. 2005 May 27;331(1):127-31. doi: 10.1016/j.bbrc.2005.03.139.
Methyl mercaptan is derived from l-methionine by the action of l-methionine-alpha-deamino-gamma-mercaptomethane lyase (METase) and is a major component of oral malodor. This compound is highly toxic and is thought to play an important role in periodontal disease. We found that Treponema denticola, a member of the subgingival biofilm at periodontal disease sites, produced a large amount of methyl mercaptan even at low concentration of l-methionine. METase activity in a cell-free extract from T. denticola was detected by two-dimensional electrophoresis under non-denaturing conditions, and the protein spot that exhibited high METase activity was identified using a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer. The identified gene produced a METase with a K(m) value for l-methionine (0.55mM) that is much lower than those of METases previously identified in the other organisms. This result suggests that T. denticola is an important producer of methyl mercaptan in the subgingival biofilm.
甲硫醇由L-蛋氨酸通过L-蛋氨酸-α-脱氨基-γ-巯基甲烷裂解酶（METase）的作用产生，是口腔异味的主要成分。这种化合物剧毒，被认为在牙周疾病中起重要作用。我们发现，牙周疾病部位龈下生物膜的成员——齿垢密螺旋体，即使在低浓度L-蛋氨酸的情况下也会产生大量甲硫醇。在非变性条件下通过二维电泳检测齿垢密螺旋体无细胞提取物中的METase活性，并使用基质辅助激光解吸/电离飞行时间质谱仪鉴定出具有高METase活性的蛋白斑点。所鉴定的基因产生了一种对L-蛋氨酸的K(m)值为0.55mM的METase，该值远低于先前在其他生物体中鉴定的METase的K(m)值。这一结果表明，齿垢密螺旋体是龈下生物膜中甲硫醇的重要产生者。
