Regulating inhibitory activity of potato I-type proteinase inhibitor from buckwheat by rutin and quercetin

Construction of nanodelivery system based on the interaction mechanism between ultrasound-treated soybean whey protein and quercetin: structure, physicochemical stability and bioaccessibility

In this study, soybean whey protein (SWP) nanodelivery system was constructed through ultrasound treatment and quercetin (Que) modification. The effect of ultrasound power on the interaction mode between SWP and Que, and the formation and stability of SWP-Que nanodelivery system were investigated. Optimal ultrasound treatment (300-500 W) produced SWP-Que nanoparticles with smaller particle size, higher ζ-potential values, and more uniform dispersion. Fluorescence spectroscopy and FTIR analyses revealed that SWP primarily binds to Que through hydrophobic interactions. Ultrasound treatment induced the unfolding of the SWP structure, thereby increasing its binding affinity to Que. After 400 W sonication, the encapsulation efficiency can reach 95.63 ± 0.60 %. The SWP-Que nanoparticles protected Que from degradation under environmental stresses (heat, UV, and storage) and improved its bioaccessibility during digestion as the ultrasonic power of 400 W. This study highlights the potential of ultrasound-modified SWP nanoparticles for effective nutrient delivery.

A Conserved Tryptophan (Trp10) at the Hydrophobic Core Modulates the Stability and Inhibitory Activity of Potato I Type Inhibitors

BACKGROUND

Different inhibitor families have their own conserved three-dimensional structures, but how these structures determine whether a protein can become an inhibitor is still unknown. The buckwheat trypsin inhibitor (BTI) pertains to the Potato I type inhibitor family, which is a simple and essential bio-molecule that serves as a model for the investigation of protease-inhibitor interaction.

OBJECTIVE

To study the effects of mutations at Trp10 and Ile25 in the hydrophobic cavity (scaffold) of rBTI on its inhibitory activity and stability.

METHODS

Site-directed mutagenesis and molecular modeling were performed using the sequence of BTI. The hydrogen bonds formed by all amino acids and conformational differences of Trp53 were analyzed in the tertiary structures of rBTI and mutants.

RESULTS

Mutant rBTI-W10A almost completely lost its inhibitory activity (retaining 10%), while rBTI-I25A retained about 50% of its inhibitory activity. Both rBTI-W10A and rBTI-I25A could be degraded by trypsin. The hydrogen bond analysis results showed that mutating Trp10 or Ile25 weakened the specific cohesion interactions in the hydrophobic core of rBTI, disrupting the tight hydrogen bond network in the cavity. This further led to difficulty in maintaining the binding loop conformation, ultimately causing the Trp53 to undergo conformational changes. It was also difficult for residues in the mutants to form hydrogen bonds with amino acids in bovine trypsin; thus, the mutants could not stably bind to trypsin.

CONCLUSION

Our findings suggest that the hydrophobic core is also an important factor in the maintenance of inhibitory activity and stability of rBTI.

Mechanistic studies of polyphenols reducing the trypsin inhibitory activity of ovomucoid: Structure, conformation, and interactions

Ovomucoid (OVM) is a critical anti-nutritional factor in egg, which may reduce nutrient utilization. In this study, the effects of polyphenols on the trypsin inhibitory activity (TIA) of OVM were investigated by exploring the structural changes and interaction mechanisms. The results found that TIA decreased to 62.34% and 90.41% as epigallocatechin gallate (EGCG) and gallic acid (GA) were added individually. EGCG and GA interacted with OVM via static quenching and hydrophobic interaction. They induced a transition of OVM conformation from disorder to order. Infrared and fluorescence quenching analysis showed that the interaction between EGCG or GA and OVM was spontaneous, and hydrophobic interaction was the predominant force. The mechanism suggested that polyphenols affect the protein conformation by spontaneously binding to OVM in hydrophobic interactions, and lowering the TIA through reduced hydrophobicity. In summary, EGCG may be a promising OVM trypsin activity inactivator, which could also guarantee safety of egg products.

1H-NMR and LC-MS Based Metabolomics Analysis of Potato (Solanum tuberosum L.) Cultivars Irrigated with Fly Ash Treated Acid Mine Drainage

1H NMR and LC-MS, commonly used metabolomics analytical platforms, were used to annotate the metabolites found in potato (Solanum tuberosum L.) irrigated with four different treatments based on FA to AMD ratios, namely: control (0% AMD; tap water), 1:1 (50% AMD), 3:1 (75% AMD is 75% FA: AMD), and 100% AMD (untreated). The effects of stress on plants were illustrated by the primary metabolite shifts in the region from δH 0.0 to δH 4.0 and secondary metabolites peaks were prominent in the region ranging from δH 4.5 to δH 8.0. The 1:3 irrigation treatment enabled, in two potato cultivars, the production of significantly high concentrations of secondary metabolites due to the 75% FA: AMD content in the irrigation mixture, which induced stress. The findings suggested that 1:1 irrigation treatment induced production of lower amounts of secondary metabolites in all crops compared to crops irrigated with untreated acid mine drainage treatment and with other FA-treated AMD solutions.