Cerebrosides (Crb; including glucosylceramide and galactosylceramide) and lactosylceramide (LacCer) are structurally complex lipids found in many eukaryotic cell membranes, where they play important roles in cell growth, apoptosis, cell recognition and signaling. They are also found in mammalian milk as part of the milk fat globule membrane (MFGM), making milk an important dietary component for the rapidly growing infant. This study reports the development of a robust analytical method for the identification and characterization of 44 Crb and 23 LacCer molecular species in milk, using high performance liquid chromatography–tandem mass spectrometry in data-dependent acquisition mode. For the first time, it also compares the distributions of these species in human and bovine milks, a commercial MFGM-enriched dairy ingredient (MFGM Lipid 100) and commercial standards purified from bovine milk. A method for quantifying Crb and LacCer in milk using mass spectrometry in neutral loss scan mode was developed and validated for human milk, bovine milk and MFGM Lipid 100. Human milk was found to contain approximately 9.9–17.4 µg Crb/mL and 1.3–3.0 µg LacCer/mL, whereas bovine milk (pooled milk from a Friesian herd) contained 9.8–12.0 and 14.3–16.2 µg/mL of these lipids, respectively. The process used to produce MFGM Lipid 100 was shown to have enriched these components to 448 and 1036 µg/g, respectively. No significant changes in the concentrations of both Crb and LacCer were observed during lactation.

Here, we report on the biochemical characterisation of a new glycosylated bacteriocin (glycocin), ASM1, produced by Lactobacillus plantarum A‐1 and analysis of the A‐1 bacteriocinogenic genes. ASM1 is 43‐amino acids in length with Ser18‐O‐ and Cys43‐S‐linked N‐acetylglucosamine moieties that are essential for its inhibitory activity. Its only close homologue, glycocin F (GccF), has five amino acid substitutions all residing in the flexible C‐terminal ‘tail’ and a lower IC₅₀ (0.9 nM) compared to that of ASM1 (1.5 nM). Asm/gcc genes share the same organisation (asmH←→asmABCDE→F), and the asm genes reside on an 11,905‐bp plasmid dedicated to ASM1 production. The A‐1 genome also harbours a gene encoding a ‘rare’ bactofencin‐type bacteriocin. As more examples of prokaryote S‐GlcNAcylation are discovered, the functions of this modification may be understood.

Here we demonstrate G-quadruplex formation by oligodeoxynucleotides containing α-2′-deoxyguanosine (α-dG) as a sole source of guanosines in G₄T₄, G₄T₄G₄ and T(G₃T_n)₃G₃T sequences with various numbers of natural β-T in the loops (n = 1–4). Based on circular dichroism spectra we observed that all α-dG-containing DNAs formed G-quadruplexes with uniform arrangement of α-dG-tetrads, which implies formation of G-quadruplexes of parallel topology. In several cases, native DNA structures that usually adopt an antiparallel topology were converted to more thermally stable G-quadruplexes of parallel topology. Using 2D ROESY NMR spectra a new ‘sequential walk’ was established for α-dGs in a tetramolecular, parallel complex formed by the α-G₄β-T₄ sequence. Analysis of ROEs in α-dGs indicates that guanines in [α-G₄β-T₄]₄ adopt anti-glycosidic conformations. These results demonstrate that α-dG can be used for an antiparallel-to-parallel switch of G-quadruplex DNAs producing complexes with higher thermal stability and uniform stacking of α-dG-tetrads.