Occurrence of Peptide-Peptide Interactions during the Purification of Self-Assembling Peptide f1-8 from a β-Lactoglobulin Tryptic Hydrolysate

Self-assembling peptides have gained attention because of their nanotechnological applications. Previous work demonstrated that the self-assembling peptide f1-8 (Pf1-8) that is generated from the tryptic hydrolysis of β-lactoglobulin can form a hydrogel after several purification steps, including membrane filtration and consecutive washes. This study evaluates the impact of each processing step on peptide profile, purity, and gelation capacity of each fraction to understand the purification process of Pf1-8 and the peptide-peptide interactions involved. We showed that peptide-peptide interactions mainly occurred through electrostatic and hydrophobic interactions, influencing the fraction compositions. Indeed, the purity of Pf1-8 did not correlate with the number of wash steps. In addition to Pf1-8, two other hydrophobic peptides were identified, peptide f15-20, and peptide f41-60. The gelation observed could be induced either through peptide-peptide interactions or through self-assembling, both being driven by non-covalent bond and more specifically hydrophobic interactions.

EFFECTS OF ALPHA-S1-CASEIN TRYPTIC HYDROLYSATE AND L-THEANINE ON SLEEP DISORDER AND PSYCHOLOGICAL COMPONENTS: A RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED STUDY

Sleep disorder is common among the general population. A nutritional supplement containing alpha-s1-casein tryptic hydrolysate and L-theanine was evaluated for its effects in improving sleep quality. The study was conducted using a double-blind randomized trial. Intervention group received once-daily capsules of 150 mg alpha s1 casein tryptic hydrolysate and 50 mg L-theanine, and the control group were given placebo (150 mg skimmed milk powder) for four weeks. The outcome measurements were assessed on weekly basis using PSQI, DASS-21, clinical and biochemical parameters. ANOVA test were used to assess within group differences and ANCOVA were used to check for differences between groups. Significantly lower (better) sleep latency score, sleep disturbances score and daytime dysfunction score were demonstrated on week-4 in intervention group compared to placebo group. Profound differences were observed between the two groups for anxiety and stress scores from week-3 onwards, in which lower anxiety and stress scores were observed in intervention group compared to placebo group. In addition, significantly lower depression score in intervention group compared to placebo group on week-4 was observed. Intervention supplement has demonstrated potent effects in relieving anxiety, stress, depression and sleep quality.