Rosen B P, Hackette S L
J Bacteriol. 1972 Jun;110(3):1181-9. doi: 10.1128/jb.110.3.1181-1189.1972.
The release of enzymes by osmotic shock from Escherichia coli strain 30E, an unsaturated fatty acid auxotroph, was examined in culture supplemented with either cis- or trans-unsaturated fatty acids. Cultures grown in oleate-supplemented medium release a large fraction of the total cyclic phosphodiesterase, acid hexose phosphatase, and 5'-nucleotidase following osmotic shock. Cultures grown in elaidate-supplemented medium release much less of these same enzymes after shock treatment. Cultures grown with either supplementation show total release of these enzymes upon conversion to spheroplasts, demonstrating that the enzymes are in the periplasmic space in both cases. Cultures grown with either oleate or elaidate as fatty acid source were washed and suspended in medium containing the other isomer. The change from oleate to elaidate resulted in a rapid decrease in ability of the cells to release the three enzymes after osmotic shock so that within a 25% increase in cell mass the culture responded to osmotic shock as would a culture grown overnight in elaidate-supplemented medium. The reverse experiment resulted in a gradual increase in the ability of the cells to respond to osmotic shock. The outer membrane of E. coli is altered by the incorporation of elaidate, as indicated by electron microscopic data.
在补充了顺式或反式不饱和脂肪酸的培养基中，研究了不饱和脂肪酸营养缺陷型大肠杆菌菌株30E经渗透压冲击后酶的释放情况。在补充油酸盐的培养基中生长的培养物，经渗透压冲击后会释放大部分的总环磷酸二酯酶、酸性己糖磷酸酶和5'-核苷酸酶。在补充反油酸酯的培养基中生长的培养物，经冲击处理后释放的这些酶要少得多。无论补充哪种脂肪酸，培养物在转化为原生质球后这些酶都会完全释放，这表明在这两种情况下酶都存在于周质空间中。将以油酸盐或反油酸酯为脂肪酸来源生长的培养物洗涤后，悬浮于含有另一种异构体的培养基中。从油酸盐转变为反油酸酯导致细胞在渗透压冲击后释放这三种酶的能力迅速下降，以至于在细胞质量增加25% 以内，该培养物对渗透压冲击的反应就如同在补充反油酸酯的培养基中过夜培养的培养物一样。反向实验则导致细胞对渗透压冲击的反应能力逐渐增强。如电子显微镜数据所示，大肠杆菌的外膜因反油酸酯的掺入而发生改变。
