To define the possible conformational change introduced by the mutation or disulfide bond formation, we dialyzed Bcl xL, Bcl xL, Bcl xL and dimeric Bcl jak stat xL in sodium phosphate buffer and compared their significantly UV CD spectra. As shown in Fig. 4B, the CD spectrum of Bcl xL disulfide bond dimer may be the just like those of Bcl xL, Bcl xL and monomeric Bcl xL, indicating that the disulfide bond formation and mutation do not influence the secondary structure of Bcl xL protein. We examined the affiliation of Bcl xL disulfide bond dimer with LUV by fluorescence titration experiment, to look at perhaps the disulfide bond formation affects the lipids insertion of Bcl xL. As shown in Fig. 1B, Bcl xL disulfide connection dimer effortlessly binds to LUV at pH 4. 9. 250 the disulfide bond dimeric protein can be bound almost all by folds of LUV. To quantitatively evaluate the affiliation of Bcl xL and dimeric Bcl xL protein with LUV, the titration curves were suited to Eq. to determine the molar fraction partition coefficients x, which is in proportion with the concentration ratio of the protein in fats and in water. The molar fraction partition coefficients x for Bcl xL and dimeric Bcl xL are 4. chemical catalogs 6?105 and 3. 7?105, respectively. The similar x values suggest that Bcl xL and dimeric Bcl xL protein have similar distribution between water and lipids. Moreover, the changes in the conventional free energy in the fat attachment are?7. 075 and?6. 962 kcal/M for Bcl xL and dimeric Bcl xL, respectively. This result also demonstrates that the disulfide bond formation has little impact on the membrane attachment of Bcl xL protein. The proteins were added by the pore formation To study whether Bcl xL mutant proteins can form pores in lipid vesicles,we into 250 folds of calcein encapsulated LUV. As shown in Fig. 5A, Bcl xL causes the calcein launch at a slower rate compared to the wild type Bcl xL. The sequence alignment analysis Mitochondrion of Bcl 2 family proteins with multiple BH areas shows that Cys151 of Bcl xL is not a conserved residue. Though Cys151 is replaced by Ala or Val in Mcl 1 or Bax, both proteins adopt the similar folding as Bcl xL. Thus, the mutation of C151A in Bcl xL is unlikely to alter the protein folding. Constantly, the CD spectra declare that the secondary structure of Bcl xL is thesameas thatofBcl xL. On one other hand, the crystal structure of Bcl xL implies that Cys151 types hydrophobic interactionswith Leu13, Phe27, Val163, and Ile166. If the mutation hedgehog pathway inhibitor of C151A has any influence, thatwould be destabilization of the protein structure, which should benefit the pore formation. Infact, themutationreducesthepore formingrate. Therefore, the slower pore forming price of Bcl xL looks maybe not because of altered protein structure. It may be explained by the fact on the pore forming 5helix that the mutation has changed the polarity of a residue.