The Effect of Lipidation on the Self-Assembly of the Gut-Derived Peptide Hormone PYY_3–36

Abstract

Lipidation is a powerful strategy to improve the stability in vivo of peptide drugs. Attachment of a lipid chain to a hydrophilic peptide leads to amphiphilicity and the potential for surfactant-like self-assembly. Here, the self-assembly and conformation of three lipidated derivatives of the gastrointestinal peptide hormone PYY is examined using a comprehensive range of spectroscopic, scattering, and electron microscopy methods and compared to those of the parent PYY peptide. The peptides are lipidated at Ser(11), Arg(17), or Arg(23) in the peptide; the former is within the β-turn domain (based on the published solution NMR structure), and the latter two are both within the α-helical domain. We show that it is possible to access a remarkable diversity of nanostructures ranging from micelles to nanotapes and fibrillar hydrogels by control of assembly conditions (concentration, pH, and temperature). All of the lipopeptides self-assemble above a critical aggregation concentration (cac), determined through pyrene fluorescence probe measurements, and they all have predominantly α-helical secondary structure at their native pH. The pH and temperature dependence of the α-helical conformation were probed via circular dichroism spectroscopy experiments. Lipidation was found to provide enhanced stability against changes in temperature and pH. The self-assembled structures were investigated using small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM). Distinct differences in nanostructure were observed for lipidated and unlipidated peptides, also depending on the position of lipidation. Remarkably, micelles containing lipopeptides with α-helical peptide conformation were observed. Gelation was observed at higher concentrations in certain pH intervals for the lipidated peptides, but not for unlipidated PYY. Thus, lipidation, in addition to enhancing stability against pH and temperature variation, also provides a route to prepare PYY peptide hydrogels. These findings provide important insights into the control of PYY conformation and aggregation by lipidation, relevant to the development of future therapeutics based on this peptide hormone, for example, in treatments for obesity.

Influence factors on the critical micelle concentration determination using pyrene as a probe and a simple method of preparing samples

“…Therefore, their CMC values need to be measured in their practical applications and research [8][9][10][11][12][13]. Among current methods for CMC determination, the fluorescence method based on the fluorescent change of organic probes attracts great attention owing to its high sensitivity and fast response [6,8,[14][15][16][17]. However, the fluorescent changes are usually invisible or not sharp about CMC and hence a series of samples containing different concentrations of surfactant and a certain amount of probe need to be prepared and measured by a fluorospectrophotometer.…”

“…We wondered whether method III was also suitable for other CMC probes without AIE characteristics. Considering that pyrene is the most used fluorescent probe for CMC determination [15,[29][30][31][32], we prepared samples by methods I-III and studied the factors influencing CMC determination using pyrene as probe in detail. The CMC determination using pyrene as probe is based on the linear relationship between the surfactant concentration and the ratio (I FIII /I FI ) of its fluorescence intensities at the peaks I and III.…”

Self-Assembling Peptides as an Emerging Platform for the Treatment of Metabolic Syndrome

“…Hence, the synthetic PYY formulations could facilitate the development of novel peptide solutions or peptide hydrogels with high potential to be used as pharmaceutics to address obesity in a more stable and extended manner in comparison to medications, such as Liraglutide. 26 Nevertheless, further research would shed light for a deeper understanding of the assembly of PYY peptides to develop effective and safer anti-obesity drugs.…”

“…Furthermore, peptide-based formulations, such as matrices or solutions are being designed to develop novel pharmaceutics with increased efficacy, safety, and tolerability for treating hyperglycemia 25 and obesity. 26 In this review, the potential and current limitations related to peptide-based formulations to address metabolic syndrome and related chronic diseases are concisely provided and discussed.…”

Melanin production by tyrosinase activity on a tyrosine-rich peptide fragment and pH-dependent self-assembly of its lipidated analogue

“…Examples include insulin for the treatment of diabetes, 1 oxytocin to induce labour, 3 and thymalfasin to act as an adjuvant for both influenza and hepatitis B vaccines. [4][5][6][7] Our group has recently been studying the conformation and self-assembly of the gut peptide hormone PYY3-36 and lipidated 8,9 and PEGylated 9 derivatives as well as and the N-terminal domain IKPEAP (GE) and its N-terminal palmitoylated derivative. 10 PYY3-36 and its derivatives are a promising target for the treatment of obesity and type II diabetes.…”