Lanzhou Institute of Husbandry and Pharmaceutical Sciences, Chinese Academy of Agricultural Sciences, 730050, Lanzhou, China.
Key Laboratory for Yak Genetics, Breeding, and Reproduction Engineering of Gansu Province, 730050, Lanzhou, China.
BMC Vet Res. 2020 Oct 23;16(1):401. doi: 10.1186/s12917-020-02620-z.
Lactoferricin (Lfcin) is an antimicrobial activity center of lactoferrin, produced by hydrolysis from the N-terminal of lactoferrin. It was hypothesized that the intramolecular disulfide bond in Lfcin could affect its antibacterial function through influencing its molecular structure. To prove this hypothesis, bovine Lfcin (bLfcin) and its two derivatives, bLfcin with an intramolecular disulfate bond (bLfcin DB) and bLfcin with a mutation C36G (bLfcin C36G), were synthesized, purified, and identified. The circular dichroism spectra of the peptides were detected in solutions with different ionic and hydrophobic strength. The antibacterial activity of the peptides against Trueperella pyogenes, separated from cow milk with mastitis, were determined.
The secondary structure of bLfcin DB showed more β-turn and less random coil than the other peptides in HO, similar ratios of secondary structures with bLfcin and bLfcin C36G under ionic conditions, and close percentages of secondary structure with bLfcin under hydrophobic conditions. The synthetic peptides exhibited strong antimicrobial activity against T. pyogenes isolates, T. pyogenes ATCC 19,411, and E. coli ATCC 25,922. The antimicrobial activities of the three peptides were greater against T. pyogenes than against E. coli, and bLfcin DB exhibited higher antibacterial activity compared with its derivatives.
The intramolecular disulfide bond could change the molecular structure of bLfcin under alternative ionic strengths and hydrophobic effects, and the formation of the disulfide bond is beneficial to executing the antibacterial function of bLfcin.
乳铁蛋白抗菌肽（Lfcin）是乳铁蛋白的抗菌活性中心，由乳铁蛋白的 N 端水解产生。据推测，Lfcin 中的分子内二硫键可以通过影响其分子结构来影响其抗菌功能。为了验证这一假设，合成、纯化并鉴定了牛乳铁蛋白（bLfcin）及其两种衍生物：具有分子内二硫键（bLfcin DB）的 bLfcin 和突变 C36G 的 bLfcin（bLfcin C36G）。检测了肽在不同离子强度和疏水性溶液中的圆二色谱。测定了肽对从乳腺炎牛乳中分离出的化脓隐秘杆菌的抗菌活性。
bLfcin DB 的二级结构在 HO 中比其他肽具有更多的β-转角和较少的无规卷曲，在离子条件下与 bLfcin 和 bLfcin C36G 的二级结构相似比例，在疏水环境下与 bLfcin 的二级结构接近。合成肽对化脓隐秘杆菌分离株、化脓隐秘杆菌 ATCC 19411 和大肠杆菌 ATCC 25922 均具有较强的抗菌活性。三种肽对化脓隐秘杆菌的抗菌活性均强于对大肠杆菌的抗菌活性，bLfcin DB 比其衍生物具有更高的抗菌活性。
分子内二硫键可以在不同的离子强度和疏水性影响下改变 bLfcin 的分子结构，二硫键的形成有利于执行 bLfcin 的抗菌功能。
