International Journal of Biological Macromolecules最新文献

This study explores the bioactivity and intestinal absorption of peptides from Acheta domesticus (house cricket), emphasizing their potential health benefits and relevance to sustainable protein sources. Six peptides (DVW, AVQPCF, QIVW, CAIAW, PIVCF, and IIIGW) obtained from the simulated gastrointestinal digestion of the A. domesticus proteins acyl-CoA Delta12-desaturase, acyl-CoA Delta-9 desaturase and diuretic hormone receptor were assessed for their effects on gene expression markers related to diabetes (DPP-4, SGLT1) and hypertension (sACE, ACE2). Using Caco-2 cells to model intestinal absorption, the peptides were evaluated for transport, cytotoxicity, and impact on barrier integrity. All peptides were non-cytotoxic up to 2 mM; however, DVW and PIVCF disrupted epithelial integrity. Only DVW crossed the epithelium intact. While none of the peptides significantly affected sACE or ACE2 expression, DVW and PIVCF notably downregulated SGLT1 expression (to 0.42- and 0.52-fold, respectively), suggesting potential antidiabetic effects through reduced glucose absorption.

This work emphasizes the potential application of underutilized herb like Cucumis callosus for encapsulating various drugs/active ingredients for health and agricultural purposes in terms of antioxidant and antimicrobial activity. Proteins extracted from C. callosus seeds were thoroughly characterized by SDS PAGE and LC-MS before making its nanoparticles for encapsulating Astraeus hygrometricus organic extract exploring its antimicrobial and anti-oxidant properties. FE-SEM data showed particle size in the range of 48-151 nm for control nanoparticles (CNPs) and 55-150 nm for loaded nanoparticles (LNPs). DLS measurements showed average particle size and zeta potential of 309 nm and - 17.8 mV, for CNPs and 241.1 nm and - 32.9 mV, for LNPs, respectively. Hydrophobic interaction between organic extract and protein were exploited for encapsulation. Antioxidant activity was determined by DPPH and ABTS assay. Antioxidant and anti-microbial activity of synthesized nano formulation (LNPs) showed a significant reduction in MIC and IC50 compared to protein and extract alone.

Moringa oleifera, a plant of significant medicinal and edible value, is renowned for its bioactive compound isothiocyanates (ITCs) with multiple health benefits. This study investigates the biosynthetic mechanism of ITCs in M. oleifera. Local BLAST alignment and KEGG pathway analysis of the Moringa genome identified nine key genes encoding six enzymes-BCAT, CYP79F1, CYP83A1, UGT, SOT, and MYR-potentially involved in ITCs biosynthesis. Expression correlation analysis showed that only myrosinase genes MoMYR1 and MoMYR3 exhibited significant positive correlation with sulforaphane content across tissues (p < 0.05). The MoMYR1 gene (GeneBank: PP738617) was successfully cloned for the first time. Heterologous expression in Escherichia coli BL21 produced recombinant MoMYR1 protein, while expression in Pichia pastoris GS115 yielded no detectable MoMYR3 protein. Molecular docking revealed a binding energy of -8.0 kcal/mol between the protein and substrate, indicating strong affinity. In vitro enzymatic assays demonstrated that recombinant MoMYR1 catalyzed Sinigrin and GL with specific activities of 0.2565 and 0.2447 μmol·(min·mg)^-1, and catalytic efficiencies of 30.17 and 28.79 U·g^-1, respectively. LC-MS analysis confirmed the conversion of GL to sulforaphane by heterologously expressed MoMYR1. This study identifies MoMYR1 as a key enzyme gene in ITCs biosynthesis in Moringa oleifera, providing a theoretical foundation and critical target for elucidating regulatory mechanisms and developing green production strategies.

Three Polygonatum species, namely Polygonatum sibiricum Red., Polygonatum kingianum Coll. et Hemsl., and Polygonatum cyrtonema Hua, are officially designated as Huangjing (Polygonati Rhizoma) in the Pharmacopoeia of the People's Republic of China (PPRC). This study aimed to compare the effects of different ultrasound-assisted enzymatic hydrolysis durations and these three species on the bioactivity of functional polysaccharides extracted therefrom. To achieve this goal, six homogeneous polysaccharides-PSP50N, PSP95N, PKP50N, PKP95N, PCP50N, and PCP95N-were successfully purified from the above-mentioned three Polygonatum species. Among these polysaccharides, those polysaccharides obtained via 50 min of ultrasound-assisted enzymatic hydrolysis exhibited significantly superior bioactivity compared with those obtained through 95 min of the same treatment. The primary structures of the six polysaccharides, including molecular weight, fructose content, and chain conformation, were characterized, and obvious differences were observed among them. Although all three Polygonatum species showed similar efficacy profiles in terms of antioxidant, glucose-lowering, antitumor, and immunomodulatory activities, their potencies differed significantly. Specifically, PSP95N exerted potent antitumor activity by inducing mitochondrial dysfunction, cell cycle arrest, and apoptosis, while PSP50N exerted stronger immunomodulatory effects by activating the TLR4/NF-κB pathway. Partial Least Squares (PLS) analysis identified molecular weight and fructose content (VIP > 1.2) as the key structural factors responsible for grouping the polysaccharides by ultrasound-assisted enzymatic hydrolysis duration. Entropy-weighted TOPSIS evaluation ranked their comprehensive bioactivity as follows: PSP50N > PCP50N > PKP50N > PCP95N > PSP95N > PKP95N, thus confirming 50 min as the optimal hydrolysis duration for extracting polysaccharides with high bioactivity. This study enhances the understanding of the structure-activity relationship of polysaccharides and provides a theoretical basis for the clinical Polygonatum species selection.

LuxR/HapR homologues play important roles in the regulation of virulence and protease genes in pathogenic Vibrio species like V. cholerae, V. vulnificus, V. parahaemolyticus, etc. as well as providing physiological advantages such as resistance to protozoan grazing, motility and chitin-induced competence in the aqueous environments. They are commonly termed as the high cell density master regulators. They are highly conserved in sequence and structure among the Vibrios and can recognize and bind to common DNA promoters, like activation of protease production in V. cholerae by SmcR of V. vulnificus. Despite this conservation, critical differences occur due to amino acid divergence in their sequences. In the present study, we compare the degree of functional conservation among HapR/LuxR homologues selected from various clades of the Vibrionaceae family, using a hapR mutant V. cholerae strain as a model organism. We also delve into the structural intricacies of distant HapR/LuxR homologues, such as LuxR proteins of Photobacterium spp. and HapR of Vibrio mimicus, a close homologue of V. cholerae. Evolutionary implications arising from sequence divergence are also recorded in the structural changes through the crystal structure analysis. The study compared several structural constraints responsible for the variation in functions related to transcriptional regulation.

Internal ribosome entry sites (IRESs) in circular RNAs (circRNAs) are key elements that drive cap-independent translation, and their accurate identification is crucial for understanding circRNA function. Currently, most IRES prediction models are designed for linear RNA sequences, and models specifically for circRNAs still show suboptimal performance. To address this, we proposed a dual-attenuation fusion framework, circIRES-DAF, specifically designed for predicting IRES in circRNAs. The model captures sequence features and local contextual information through a dual-channel sequence feature extraction module; meanwhile, it integrates a graph neural network to model RNA secondary structure. Furthermore, the model introduces a dual-attenuation fusion strategy based on local feature quality evaluation and global modality importance weighting. This strategy effectively suppresses noise and enhances discriminative capability. Ablation experiments demonstrate that sequence and structural features provide complementary information, and the dual-attenuation fusion mechanism significantly improves model performance. On independent test sets, circIRES-DAF outperforms existing mainstream methods. Furthermore, interpretability analysis reveals several potential consensus motifs associated with IRES elements, providing a powerful computational tool and biological insights for circRNA research.

Mangiferin, a natural bioactive compound with multiple physiological functions, faces limitations in its oral bioavailability due to poor stability and solubility in the gastrointestinal environment. Liposome-based delivery systems have shown promise in enhancing the bioavailability of such compounds, but their stability under physiological conditions remains a challenge. In this study, mangiferin-loaded liposomes were prepared via the ethanol injection method. Using entrapment efficiency as the evaluation index, the optimal preparation conditions were determined through a combination of single-factor and orthogonal experiments. The mangiferin liposomes were further subjected to layer-by-layer coating using whey protein and κ-carrageenan. Three types of liposomes-mangiferin liposomes (ML), whey protein-coated mangiferin liposomes (W-ML), and whey protein-κ-carrageenan modified mangiferin liposomes (W/C-ML) were compared in terms of encapsulation efficiency, structural characteristics, and stability. The results demonstrated that the double-layer modified liposomes (W/C-ML) achieved a significantly higher entrapment efficiency of 70.63% ± 0.86% and exhibited superior physical stability. In vitro digestion studies revealed that the W/C-ML group had the highest release rate and cumulative release rate in simulated intestinal fluid. The findings offer valuable insights into the design of oral delivery systems for poorly soluble bioactive compounds, with potential applications in functional foods and nutraceuticals.

Enhancing the stability of acid proteases is crucial for their long-term storage and diverse industrial applications, particularly in high-temperature or long-duration processes, such as wet blue bating in leather manufacturing. On the basis of classical tanning theory, this study investigated the stabilization effects of tanning metal ions, Cr³⁺, Al³⁺, and Zr⁴⁺, on pepsin, a model acid protease for wet blue bating. Fluorescence spectroscopy and molecular docking results indicated that Cr³⁺, Al³⁺, and Zr⁴⁺ interacted with pepsin through static quenching, primarily dominated by hydrogen bonds and van der Waals forces in addition to coordination. Cr³⁺, Al³⁺, and Zr⁴⁺ did not bind to the active site of pepsin, thereby preserving its catalytic function. Pepsin exhibited enhanced storage stability, heat resistance, and application stability in the presence of these polyvalent metal ions. At molar ratios of pepsin to Cr³⁺, Al³⁺, and Zr⁴⁺ of 1:28, 1:24, and 1:20, respectively, the residual activities of pepsin were 88-96% after 48 h of incubation at 37 °C, above 92% after 12 h of incubation at 55 °C, and 36-38% after 8 h of reaction at 37 °C, all much higher than those of untreated pepsin. These enhanced stabilities are likely attributable to the formation of stable ground-state complexes between pepsin and metal ions, which reinforce the structural integrity of pepsin. This study not only presents a novel strategy for achieving efficient and stable acid proteases for leather bating but also offers a theoretical foundation for understanding how metal ions stabilize enzymes.