Since the discovery and use of antibiotic compounds in the early 20th century, an increasing amount of bacteria have evolved resistance. The problem with resistance leads to the discovery of many new compounds, but from the 80’s and onwards there has been a discovery void. This has turned scientist towards new antibiotic strategies to investigate antimicrobial peptides (AMP), so that they could be applied medically. One of the hurdles in this process is knowledge on their molecular structure and the mode of action. In this report we shed new light on the structure and function of OP-145, an engineered AMP derived from the LL-37 sequence observed in the human immune system. The crystallization of OP-145 for structural studies did not yield any usable results, but indications of which conditions to avoid in further crystallization efforts have been gathered. The growth inhibition experiment running for a course of 4 hours on the bacteria E. coli and B. subtilis with the antimicrobial peptides compared with traditional antibiotics, shed some light on their effectiveness and mode of action. The conditions under which the antibiotics work is crucial for their effect and so is the structure related to effectiveness of their mode of action. LL-37 showed significant results in halting E.coli growth at a concentration of 6.7 µM, while it and OP-145 had a surprising significant growth enhancing effect on B. subtilis. OP-145 did not suppress bacterial cell growth at any of the used concentrations (2.5 µM to 19.7 µM) which was also discovered for the lysozyme at concentrations (1.8 µM to 14 µM for B. subtilis and 3.5 µM to 28 µM for E. coli). The effort to check for a synergistic effect between vancomycin and either LL-37 or OP-145 did not show the desired effect, except in the case of one mixture treatment which delayed the bacteria growth (3.3 µM LL-37 and 10.8 µM vancomycin). While in the case of B. subtilis it can be suggested that the presence of AMPs enhanced the resistance towards the traditional antibiotics possibly by increasing the availability of amino acids.
|Uddannelser||Molekylærbiologi, (Bachelor/kandidatuddannelse) Bachelor el. kandidat|
|Udgivelsesdato||19 jan. 2016|