Abdel-Shafi Seham, Osman Ali, Enan Gamal, El-Nemer Mona, Sitohy Mahmoud
Botany Department, Faculty of Science, Zagazig University, Zagazig, 44519 Egypt.
Biochemistry Department, Faculty of Agriculture, Zagazig University, Zagazig, 44511 Egypt.
Springerplus. 2016 Jul 4;5(1):983. doi: 10.1186/s40064-016-2625-3. eCollection 2016.
Native egg white protein with high level of acidic amino acid residues (pI = 4.8) and hydrophilic nature was transformed into its methylated derivative (MEW), acquiring rather hydrophobic and basic character (pI = 8). The MIC of MEW against ten studied bacteria (G(+) and G(-)) ranged between 0.5 and 1 μg/disc matching or excelling the comparative values of some known specific antibiotics (ranging from 1 to 7.5 μg/disc). Combinations of MEW (1 MIC) and different ready-made disc concentrations of antibiotics indicated either nil, antagonistic or synergistic antimicrobial effect. Replacing the antibiotic Ciprofloxacin by gradual levels of MEW (20-100 %) proportionally increased the potentiality to induce bigger sized inhibition zones. MEW (1 MIC) could inhibit the growth of 6 G(+) and 4 G(-) pathogenic bacteria in their liquid broth media during 24 h at 37 °C, indicating its broad and wide specificity. TEM examination indicated the susceptibility of the two types of bacteria (G(+) and G(-)) to the antimicrobial action of MEW as manifested in different signs of cellular deformations, confirming its broad specificity and its mode of action was rather targeting the cell wall and cell membrane.
具有高酸性氨基酸残基水平（pI = 4.8）和亲水性的天然蛋清蛋白被转化为其甲基化衍生物（MEW），获得了相当疏水和碱性的特性（pI = 8）。MEW对十种受试细菌（革兰氏阳性菌和革兰氏阴性菌）的最低抑菌浓度在0.5至1μg/圆盘之间，与一些已知特定抗生素的比较值相当或更优（范围为1至7.5μg/圆盘）。MEW（1个最低抑菌浓度）与不同现成圆盘浓度的抗生素组合显示出无抗菌作用、拮抗或协同抗菌作用。用逐渐增加水平的MEW（20 - 100%）替代抗生素环丙沙星，成比例地增加了诱导更大尺寸抑菌圈的潜力。MEW（1个最低抑菌浓度）在37℃下24小时内可抑制6种革兰氏阳性菌和4种革兰氏阴性致病菌在其液体肉汤培养基中的生长，表明其具有广泛的特异性。透射电子显微镜检查表明两种类型的细菌（革兰氏阳性菌和革兰氏阴性菌）对MEW的抗菌作用敏感，表现为不同的细胞变形迹象，证实了其广泛的特异性，其作用方式相当于是靶向细胞壁和细胞膜。
