Smalley J W, Birss A J, McKee A S, Marsh P D
Department of Clinical Dental Sciences, University of Liverpool, UK.
FEMS Microbiol Lett. 1996 Jul 15;141(1):65-70. doi: 10.1111/j.1574-6968.1996.tb08364.x.
Haemin (iron protoporphyrin IX) is an essential growth factor for the periodontal pathogen. Porphyromonas gingivalis. Iron protoporphyrin IX (IPP IX) binding to the avirulent P. gingivalis beige variant (W50/BE1) and the black-pigmenting parent wild-type strain W50 was quantified. W50/BE1 grown in a chemostat under haemin excess-bound IPP IX under both oxidising and reducing conditions but with both lower capacity and avidity than either the haemin-limited- and haemin-excess-grown parent strain W50. Rosenthal plots for W50/BE1 indicated cooperative binding. W50/BE1 cells expressed a 32 kDa outer membrane haemin-binding protein when grown under conditions of haemin excess, and this strain might serve as a useful source from which to isolate this protein. The reduced IPP IX binding ability of W50/BE1 may be the rate-limiting factor for haem uptake and explain the reduced virulence and slower rate of pigmentation of this strain.
血红素（铁原卟啉IX）是牙周病原体牙龈卟啉单胞菌的一种必需生长因子。对无毒力的牙龈卟啉单胞菌米色变体（W50/BE1）和产黑色素的亲本野生型菌株W50与铁原卟啉IX（IPP IX）的结合进行了定量分析。在恒化器中生长的W50/BE1在血红素过量的情况下，无论在氧化还是还原条件下都能结合IPP IX，但结合能力和亲和力均低于血红素限制生长和血红素过量生长的亲本菌株W50。W50/BE1的罗森塔尔图表明存在协同结合。当在血红素过量的条件下生长时，W50/BE1细胞表达一种32 kDa的外膜血红素结合蛋白，该菌株可能是分离这种蛋白的有用来源。W50/BE1的IPP IX结合能力降低可能是血红素摄取的限速因素，并解释了该菌株毒力降低和色素沉着速度减慢的原因。
