| 3625 Actinobacillus actinomycetemcomitans Demonstrates Gamma-glutamyltransferase Activity Involved Potentially in H2S Production | ||
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L. CHU, University of Texas San Antonio / Health Science Ctr, USA, and L. SONG, University of Texas San Antonio / Health Science Ctr, USA Hydrogen sulfide (H2S) has been implicated in the development of periodontal disease. Glutathione (GSH) is an important thiol source for H2S production in periodontal pockets. Our previous studies have described a pathway of glutathione metabolism in Treponema denticola, with H2S as one of the final products. Three enzymes, GGT, cysteinylglycinase and cystalysin, are involved in this three-step pathway. Most of oral bacterial species cannot utilize GSH to produce H2S. Objective: To determine g-glutamyltransferase (GGT) activity in Actinobacillus actinomycetemcomitans (A.a) and to determine A.a 's role in H2S production from periodontal pathogens. Methods: Twenty-five species of oral bacteria were grown on sheep agar plates and then in respective broth. Na-¦Ã-glutamyl-4-nitroaniline (GNA) is used as substrate for analysis of GGT activity. GSH, cysteinyglycine (Cys-Gly) and L-cysteine (Cys) are used as substrates for H2S production. HPLC is used to determine the enzyme products. Results: Among the selected species, A. actinomycetemcomitans (A.a) is one of a few oral bacteria (including T. denticola), which expressed significant GGT activities. However, A.a failed to catalyze Cys-Gly and Cys. The GGT activity of A.a was partially determined. A.a can catalize GSH into Cys-Gly and Cys. The optimal pH for GGT enzyme reaction is between 6.9 and 7.1. The Km value of GGT enzyme is 0.128 mM of GNA. Another two pathogens, Porphyromonas gingivalis and Fusobacterum nucleatum, can not catalyze GNA and GSH. However, they can catalyze Cys-Gly and Cys into H2S and other enzyme products. Interestingly, the addition of A.a to P. gingivalis and F. nucleatum results in the capacity of the bacteria to produce H2S using GSH as substrate. Conclusions: The results show A. actinomycetemcomitans, a periodontal pathogen, has g-glutamyltransferase activity and may participate in H2S production while cohabitate with other periodontal pathogens. (Supported by NIDCR grant DE-13819). | ||
| Seq #370 - Actinobacillus actinomycetemcomitans 10:15 AM-11:30 AM, Saturday, 13 March 2004 Hawaii Convention Center Exhibit Hall 1-2 | ||
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