In such a proline-rich sequence, a proline kink has all the potential to create pores [57]. It was cogently argued that in cationic hydrophobic peptides the presence of polar residues confers a hydrophilic property to the proline-rich peptides. In an earlier study conducted on curvaticin FS47, the neutral (Gly [24%]) and hydrophobic (Ala, Ile, Leu, Val, Pro, and Phe [47%]) residues at the N-terminal constitute a significant proportion which helps to explain the hydrophobic interactions that curvaticin FS47 displays. It was
reasoned that the high proportion of Gly residues (23.9% in ACP) would likely provide a significant AZD6244 chemical structure amount of flexibility to the antimicrobial molecule [58]. In fact, the increase of hydrophobicity of the peptides also correlated with fungicidal activity [59]. In accordance with many other bacteriocins of LAB e.g., lactococcin A [60], lactacin F [61], and curvaticin FS47 [58], a high proportion of glycine was likely to provide a significant amount of flexibility to the molecule. A recent study
on lactococcin G, enterocin 1071B, and EntC2 suggested that the N-terminal sequence of the peptide of each bacteriocin (LcnGβ, Ent1071B and EntC2) is important for determining target cell specificity [23, 62]. Previously, the N- terminal sequence of the antimicrobial dermaseptin B was reported to be highly hydrophobic which could enable its binding to ID-8 zwitterionic outer and negatively charged selleck chemicals llc surfaces [63]. In addition, the part of the N-terminal sequence which contains Gly-Pro residues and the combined de novo sequence detected in the anti-Candida protein ACP 43 under current investigation, were supported by the inference that proline-rich peptides (often associated with arginine) enter cells without membrane lysis and after entering the cytoplasm bind to and inhibit
the activity of specific Avapritinib nmr molecular targets causing cell death [64]. Other studies with model amphipathic all L- amino acid peptides with the sequence KX3KWX2KX2K, where X = Gly, Ala, Val, or Leu showed that the leucine-rich peptide, rather than the Ile- or Val-containing peptide, was particularly antimicrobial [63]. Our result is in agreement with this observation: leucine amounted to 19.6%, and proline (13.0%) was in association with arginine. The combined sequence derived from the de novo sequencing, WLPPAGLLGRCGRWFRPWLLWLQ SGAQY KWLGNLFGLGPK, showed high content of glycine (17.5%), proline, leucine and tryptophan. The amino acid content also revealed that the peptide was quite hydrophobic due to the presence of high amounts of leucine (22.5%), and this is believed to play a role in the interactions with the cell membrane [61]. The hydrophobicities (GRAVY) of individual peptides having m/z 718, 1039 and 601 were 0.108, -0.388 and 0.