The first electron at the Qi-site generates a relatively stable semiquinone which is reduced to quinol by the second electron. Items sold by the are not for immediate resale. Full text, or Abstract. Z. Zhang, L. Huang, V. M. Shulmeister, Y.-I. Chi, K.-K. Kim, L.-W. Hung, A. R. Crofts, E. A. Berry & S.-H. Kim. Assuming that cyt bH is close to the antimycin binding site, the arrangement in the protein is as expected from models based on mechanistic studies and structural prediction.