Porphyromonas gingivalis SOD における活性中心近傍に局在するアミノ酸残基の金属特異的活性における関与：Leu ₇2 Trp およびLeu ₇6 Phe の2残基変異による検討

The role of superoxide dismutase (SOD) as a radical scavenger in Porphyromonas gingivalis is well documented. P. gingivalis SOD (Pg SOD), which is characterized by a metal–tolerant activity, can use either iron or manganese as a cofactor. Leu ₇2 and Leu ₇6, located near the active–site metal, are characteristic amino acid sequences of Pg SOD proteins, although they are substituted to Trp in the ₇2 position and Phe in the ₇6 position in most iron–containing SOD (Fe–SOD) proteins. In the present study, we constructed a mutant of the enzyme with changes from Leu ₇2 to Trp and Leu ₇6 to Phe. This mutant SOD was examined with respect to its metal–dependent activity and structural characterization. We herein conclude the integrity of Leu ₇2 and Leu ₇6 is a necessary requisite for the metal–tolerant activity of Pg SOD

Porphyromonas gingivalis スーパーオキシドジスムターゼの構造における72位Leu をTrp に置換した影響

Porphyromonas gingivalis contains a single constitutive superoxide dismutase (SOD) that is active with either iron or manganese at the active site. The aim of this work was to evaluate the effect of the Leu ₇2 to Trp mutation on the structure of P. gingivalis SOD (Pg SOD) using lectrophoretic characterization. Leu ₇2, which is located near the active site metal, is substituted with Trp in aligned amino acid sequences of iron–containing SOD. The results of electrophoretic characterization and the expressed activity of mutant SOD suggest that mutant SOD have the same gross structure as wild–type SOD. We herein conclude that the integrity of Leu ₇2 is a necessary requisite for the metal–tolerant activity of Pg SOD