A stability transition at mildly acidic pH in the alpha‐hemolysin (alpha‐toxin) from Staphylococcus aureus

FEBS Letters

Bortoleto, Raquel Kely²  Ward, Richard J¹ 

[1] Department of Chemistry, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto-USP (FFCLRP), Avenida Bandeirantes 3900, Ribeirão Preto, SP, Brazil;Department of Physics, IBILCE/UNESP, Rua Cristovão Colombo 2265, São José do Rio Preto, SP, Brazil

关键词: α-Hemolysin;    Stability transition;   

DOI  :  10.1016/S0014-5793(99)01246-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The effects of mildly acidic conditions on the free energy of unfolding (ΔG _u ^buff) of the pore-forming alpha-hemolysin (αHL) from Staphylococcus aureus were assessed between pH 5.0 and 7.5 by measuring intrinsic tryptophan fluorescence, circular dichroism and elution time in size exclusion chromatography during urea denaturation. Decreasing the pH from 7.0 to 5.0 reduced the calculated ΔG _u ^buff from 8.9 to 4.2 kcal mol⁻¹, which correlates with an increased rate of pore formation previously observed over the same pH range. It is proposed that the lowered surface pH of biological membranes reduces the stability of αHL thereby modulating the rate of pore formation.

【 授权许可】

Unknown