Aspartate Research Articles

Insights into the role of cyclopropane fatty acid synthase (CfaS) from extreme acidophile in bacterial defense against environmental acid stress.

The cell membrane remodeling mediated by cyclopropane fatty acid synthase (CfaS) plays a crucial role in microbial physiological processes resisting various environmental stressors, including acid. Herein, we found a relatively high proportion (24.8%-28.3%) of cyclopropane fatty acid (CFA) Cy-19:0 in the cell membrane of a newly isolated extreme acidophile, Acidithiobacillus caldus CCTCC AB 2019256, under extreme acid stress. Overexpression of the CfaS encoding gene cfaS2 in Escherichia coli conferred enhanced acid resistance. GC-MS analysis revealed a 3.52-fold increase in the relative proportion of Cy-19:0 in the cell membrane of the overexpression strain compared to the control. Correspondingly, membrane fluidity, permeability and cell surface hydrophobicity were reduced to varying degrees. Additionally, HPLC analysis indicated that the overexpression strain had 1.54-, 1.42-, 1.85-, 1.20- and 1.05-fold higher levels of intracellular glutamic acid, arginine, aspartic acid, methionine and alanine, respectively, compared to the control. Overall, our findings shed light on the role of CfaS derived from extreme acidophile in bacterial defense against environmental acid stress, potentially facilitating its application in the design and development of industrial microbial chassis cells for organic acid production.

Asymmetric Pore Windows in Pillar-Layered Metal-Organic Framework Membranes for H2/CO2 Separation.

In this study, a novel ultramicroporous pillar-layered Ni-LAP-NH2 [Ni2(l-asp)2(Pz-NH2)] (l-asp = l-aspartic acid, Pz-NH2 = aminopyrazine) membranes on porous α-Al2O3 tubes with high performance and good thermal stability was first fabricated using isostructural Ni-LAP[Ni2(l-asp)2(Pz)] (Pz = pyrazine) crystals as seeds. Utilizing the principle of reticular chemistry, here, we introduced the active amino side group into the Ni-LAP frameworks by replacing the pillar-layered ligand Pz with Pz -NH2 while maintaining the original Ni-LAP small pore size, and the amino side group induced a "steric hindrance" effect and the physical adsorption affinity, which synergistically delayed CO2 penetration. It was found that the preferential (111) orientation Ni-LAP-NH2 membrane (Z10) exhibited a high H2/CO2 separation performance with a separation factor of 41.7 and H2 permeance of 9.08 × 10-8 mol·m-2·s-1·Pa-1 under optimal conditions. These MOF materials demonstrated potential for industrial H2 purification due to their tunable pore structure and remarkable stability. Moreover, this strategy offers an effective approach to tailoring pillar-layered MOF membranes with targeted molecular sieving ability.

Performance of Forensic Age Estimation by Aspartic Acid Racemization and DNA Methylation: A Systematic Review

Background Forensic age estimation is not difficult when the body is found in good condition, but in cases of severe decomposition or damage, such as burnt or separated body parts, then the analysis can only be done with bones and teeth. There has been abundant research and development in the field of related biochemistry over the years. Various molecular changes occur in hard tissues and long-lived proteins, such as those in bones and teeth during the physiological process of aging. Aspartic acid racemization and DNA methylation are still the most frequently used age estimation methods because of their advantages in accuracy. Method This study aimed to compare the accuracy of DNA methylation and aspartic acid racemization methods for age estimation. Journal articles were searched in the electronic databases PubMed, Scopus, and Semantic Scholar of 2017-2022 according to PRISMA guidelines. Result Twelve journal articles were eligible for review. The DNA methylation method is quite simple to use because of commercially available methylation kits. Furthermore, the results can be obtained relatively quickly without requiring many samples, and the method is less sensitive to thermal and other damage than the aspartic acid racemization method. Conclusion The aspartic acid racemization method for age estimation has high accuracy, especially in determining age at death. However, temperature and the condition of the teeth affect the racemization of aspartic acid. Given that DNA methylation is generally stable in a wide range of temperatures, it provides a better approach to determining the chronological age even from charred remains.

Enzymatization of Nila Fish (Oreochromis Niloticus) Protein Hydolysate by Combination of Bromelin and Pepsin Enzymes

Nile Tilapia (Oreochromis niloticus) is a freshwater fish with better nutritional content compared to other freshwater fish, making it suitable for use as a source for protein hydrolysate production. Protein hydrolysate is the result of the breakdown of protein into short-chain compounds through hydrolysis. This research aims to hydrolyze the minced Nile tilapia meat using a combination of bromelain and pepsin enzymes at a concentration of 5% and pH 7 conditions for 5-6 hours. The hydrolysis results using the combination of bromelain and pepsin enzymes (B100: P0) have a yield value of 12.68%, ash content of 2.94%, protein of 57.25%, water 2.65%, and fat 10.25% with a degree of hydrolysis of 61.46%. The hydrolysate has antibacterial properties against Staphylococcus aureus and Escherichia coli bacteria with inhibition zones of approximately 8.3 mm and 8.5 mm, respectively, at a concentration of 1 (mg/µL), contains 15 types of amino acids with the highest composition being lysine 5.12% and the highest non-essential amino acid being aspartic acid 5.75%.

The metabolic engineering of Escherichia coli for the high-yield production of hypoxanthine.

Hypoxanthine, prevalent in animals and plants, is used in the production of food additives, nucleoside antiviral drugs, and disease diagnosis. Current biological fermentation methods synthesize quantities insufficient to meet industrial demands. Therefore, this study aimed to develop a strain capable of industrial-scale production of hypoxanthine. De novo synthesis of hypoxanthine was achieved by blocking the hypoxanthine decomposition pathway, thus alleviating transcriptional repression and multiple feedback inhibition, and introducing a purine operon from Bacillus subtilis to construct a chassis strain. The effects of knocking out the IMP(Inosine 5'-monophosphate) branch on the growth status and titer of the strain were then investigated, and the effectiveness of adenosine deaminase and adenine deaminase was verified. Overexpressing these enzymes created a dual pathway for hypoxanthine synthesis, enhancing the metabolic flow of hypoxanthine synthesis and preventing auxotrophic strain formation. Introducing IMP-specific 5' -nucleotidase addressed the issue of adenylate accumulation. In addition, the metabolic flow of the guanine branch was dynamically regulated by the guaB gene. The supply of glutamine and aspartic acid precursors was enhanced by introducing an exogenous glnA mutant gene, overexpressing aspC, and replacing the weaker promoter to regulate the aspartic acid branching pathway. Ultimately, fermentation in a 5L bioreactor for 48h produced 30.6g/L hypoxanthine, with a maximum real-time productivity of 1.4g/L/h, the highest value of hypoxanthine production by microbial fermentation reported so far. The intracellular purine biosynthesis pathway is extensive and regulated at multiple levels in cells. The IMP branch in the hypoxanthine synthesis pathway has a higher metabolic flux. The current challenge lies in systematically allocating the metabolic flux within the branch pathway to achieve substantial product accumulation. In this study, E. coli was used as the chassis strain to construct a dual pathway for IMP and AMP(Adenosine 5'-monophosphate) synergistic hypoxanthine synthesis and dynamically regulate the guanine branch pathway. Overall, our experimental efforts culminated in a high-yield, plasmid- and defect-free engineered hypoxanthine strain.

Anchorage of bacterial effector at plasma membrane via selective phosphatidic acid binding to modulate host cell signaling.

Binding phospholipid is a simple, yet flexible, strategy for anchorage of bacterial effectors at cell membrane to manipulate host signaling responses. Phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-biphosphate are the only two phospholipid species known to direct bacterial effectors to establish inner leaflet localization at the plasma membrane. Here, selectivity of phosphatidic acid (PA) by bacterial effectors for the plasma membrane anchorage and its molecular entity was identified. C-terminal BID domain of Bartonella T4SS effectors (Beps) directed the plasma membrane localization of Beps in host cells through binding with PA. A hydrophobic segment of the 'HOOK' subdomain from BID is inserted into the bilayer to enhance the interaction of positively charged residues with the lipid headgroups. Mutations of a conserved arginine facilitating the electrostatic interaction, a conserved glycine maintaining the stability of the PA binding groove, and hydrophobic residues determining membrane insertion, prevented the anchorage of Beps at the plasma membrane. Disassociation from plasma membrane to cytosol attenuated the BepC capacity to induce stress fiber formation and cell fragmentation in host cells. The substitution of alanine with aspartic acid at the -1 position preceding the conserved arginine residue hindered BepD anchoring at the plasma membrane, a vital prerequisite for its ability to elicit IL-10 secretion in host macrophages. In conclusion, our findings reveal the PA-binding properties of bacterial effectors to establish plasma membrane localization and will shed light on the intricate mechanisms employed by bacterial effectors within host cells.

Effect of nanoemulsified and encapsulated Planiliza abu protein on fortified yogurt

AbstractFortified dairy products such as yogurt have attracted a lot of attention due to the increasing concern for public health. This study aimed to determine the effects of nanoemulsified and a microencapsulated protein hydrolysate obtained from Planiliza abu on some of the properties of yogurt. The physicochemical, rheological, microbiological, and sensory evaluation of the fortified yogurt samples stored at 4°C were assessed during 21 days. The fish protein hydrolysates (FPHs) < or >10 kDa protein were used. The amino acid profile of Planiliza abu was glutamic acid (78.99%), aspartic acid (59.53%), and lysine (53.54%). No significant change was observed in titratable acidity (TA) and pH of supplemented yogurts during refrigeration. The highest survival level of lactic acid bacteria (LAB), water‐holding capacity (WHC), and viscosity and the lowest syneresis were observed in fortified samples with FPH <10 kDa. The highest ferric reducing antioxidant power (FRAP) was achieved in yogurt fortified with nanoemulsion FPH < 10 kDa (NEh10a, 0.41 mg/g). The results showed that fortified yogurt with FPH, particularly less than 10 kDa, is among the desirable functional food with appropriate gel network and consistency as well as better taste and mouth feel, and higher overall acceptance.

Site‐Selective Construction of N‐Linked Glycopeptides through Photoredox Catalysis

AbstractThe glycosylation of peptides and proteins can significantly impact their intrinsic properties, such as conformation, stability, antigenicity, and immunogenicity. Current methods for preparing N‐linked glycopeptides typically rely on amide bond formation, which can be limited by the presence of reactive functional groups like acids and amines. Late‐stage functionalization of peptides offers a promising approach to obtaining N‐linked glycopeptides. In this study, we demonstrate the preparation of N‐linked glycopeptides through a photoredox‐catalyzed site‐selective Giese addition between N‐glycosyl oxamic acid and peptides containing dehydroalanine (Dha) under visible light conditions. Unlike traditional methods that rely on the coupling of aspartic acid and glycosylamine, this approach utilizes the conjugation of N‐glycosylated carbamoyl radicals with Dha, facilitating the straightforward modification of complex peptides.

Site-Selective Construction of N-Linked Glycopeptides through Photoredox Catalysis.

The glycosylation of peptides and proteins can significantly impact their intrinsic properties, such as conformation, stability, antigenicity, and immunogenicity. Current methods for preparing N-linked glycopeptides typically rely on amide bond formation, which can be limited by the presence of reactive functional groups like acids and amines. Late-stage functionalization of peptides offers a promising approach to obtaining N-linked glycopeptides. In this study, we demonstrate the preparation of N-linked glycopeptides through a photoredox-catalyzed site-selective Giese addition between N-glycosyl oxamic acid and peptides containing dehydroalanine (Dha) under visible light conditions. Unlike traditional methods that rely on the coupling of aspartic acid and glycosylamine, this approach utilizes the conjugation of N-glycosylated carbamoyl radicals with Dha, facilitating the straightforward modification of complex peptides.

Ameliorative Potential of Sudachitin Against Paraquat Induced Renal Toxicity in Rats Via Regulating Nrf2/Keap1 Pathway: An Inflammatory, Apoptotic and Histopathological Assessment

AbstractParaquat (PQ) is a noxious herbicide which is well known for its adverse effects on vital organs including kidneys. Sudachitin (SCN) is a plant derived flavone that is obtained from Citrus sudachi and demonstrates a range of pharmacological potentials. This investigation was executed to assess the protective effects of SCN to counteract PQ instigated renal damage in albino rats (Rattus norvegicus). Twenty‐four rats were apportioned in 4 different groups i. e., control group, PQ (5 mg/kg) intoxicated group, PQ (5 mg/kg)+SCN (20 mg/kg) cotreated group and SCN (20 mg/kg) only administrated group. Our findings revealed that exposure to PQ reduced the expressions of Nrf2 (nuclear factor erythroid 2–related factor 2) and its cytoprotective genes while escalating the expression of keap1. Furthermore, PQ intoxication reduced the activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GSR), heme‐oxygenase‐1 (HO‐1) and glutathione (GSH) contents while increasing the levels of malondialdehyde (MDA) and reactive oxygen species (ROS). Moreover, PQ exposure significantly increased the levels of neutrophil gelatinous‐associated lipocalin (NGAL), urea, kidney injury molecule‐1(KIM‐1) as well as creatine while reducing creatine clearance. Additionally, PQ upregulated the levels of inflammatory markers including interleukin‐6 (IL‐6), tumor necrosis‐ α (TNF‐ α), nuclear factor‐ κB (NF‐κB), interleukin 1beta (IL‐1β), and cyclo‐oxygenase‐2 (COX‐2). Moreover, PQ administration upregulated the expression of Bax (Bcl‐2–associated X protein) and (cysteine–aspartic acid protease) Caspase‐3 while downregulating the expressions of (B‐cell lymphoma 2 protein) Bcl‐2. Besides, PQ exposure prompted various histopathological damages in renal tissues. Nonetheless, SCN substantially restored aforementioned alterations in the renal tissues owing to its anti‐oxidative, anti‐inflammatory and anti‐apoptotic potential.

The chloroplast genome sequence and phylogenetic analysis of Rubia alata Wall and Rubia ovatifolia Z. Ying Zhang. (Rubiaceae).

Rubia alata Wall (R. alata) and Rubia ovatifolia Z. Ying Zhang (R. ovatifolia) are unique medicinal plants native to China. Sequencing their chloroplast genomes is important for understanding species differentiation and establishing phylogenetic relationships. The chloroplast genomes of R. alata and R. ovatifolia were sequenced using the Illumina HiSeq platform. The chloroplast genome of R. alata is 154,973 base pairs (bp) in length, containing a large single-copy region (LSC) of 84,801bp, a small single-copy region (SSC) of 17,138bp, and a pair of inverted repeats (IRs) of the same length. The length of the chloroplast genome, LSC, SSC, and IR regions of R. ovatifolia is 26,517bp, 84,716bp, 17,116bp and 26,517bp, respectively. Codon usag e analysis revealed that R. alata had the highest frequency of Aspartic acid (Asp) (1650 occurrences) in protein-coding sequences (CDS), while R. ovatifolia showed the highest frequency of Tyrosine (Try) (1479 occurrences). Comparative analysis of chloroplast genomes across seven species from the genus Rubia identified the most divergent coding regions, including rps16, psbI-trns-CGA, and petN, while plastid rRNAs were the most conserved. Phylogenetic analysis showed R. alata clustering with R. cordifolia (66.3% support), and R. ovatifolia clustering with Rubia podantha (100% support). These findings enhance our understanding of the chloroplast genome structure in Rubia species and provide molecular information for the future development and utilization of R. alata and R. ovatifolia resources.

A Novel P-III Metalloproteinase from Bothrops barnetti Venom Degrades Extracellular Matrix Proteins, Inhibits Platelet Aggregation, and Disrupts Endothelial Cell Adhesion via α5β1 Integrin Receptors to Arginine–Glycine–Aspartic Acid (RGD)-Containing Molecules

Viperid snake venoms are notably abundant in metalloproteinases (proteins) (SVMPs), which are primarily responsible for inducing hemorrhage and disrupting the hemostatic process and tissue integrity in envenomed victims. In this study, barnettlysin-III (Bar-III), a hemorrhagic P-III SVMP, was purified from the venom of the Peruvian snake Bothrops barnetti. Bar-III has a molecular mass of approximately 50 kDa and is a glycosylation-dependent functional metalloproteinase. Some biochemical properties of Bar-III, including the full amino acid sequence deduced from its cDNA, are reported. Its enzymatic activity is increased by Ca2+ ions and inhibited by an excess of Zn2+. Synthetic metalloproteinase inhibitors and EDTA also inhibit its proteolytic action. Bar-III degrades several plasma and ECM proteins, including fibrin(ogen), fibronectin, laminin, and nidogen. Platelets play a key role in hemostasis and thrombosis and in other biological process, such as inflammation and immunity, and platelet activation is driven by the platelet signaling receptors, glycoprotein (GP)Ib-IX-V, which binds vWF, and GPVI, which binds collagen. Moreover, Bar-III inhibits vWF- and convulxin-induced platelet aggregation in human washed platelets by cleaving the recombinant A1 domain of vWF and GPVI into a soluble ectodomain fraction of ~55 kDa (sGPVI). Bar-III does not reduce the viability of cultured endothelial cells; however, it interferes with the adhesion of these cells to fibronectin, vitronectin, and RGD peptides, as well as their migration profile. Bar-III binds specifically to the surface of these cells, and part of this interaction involves α5β1 integrin receptors. These results contribute to a better comprehension of the pathophysiology of snakebite accidents/incidents and could be used as a tool to explore novel and safer anti-venom therapeutics.

Determination of Plasma Metabolites and Basal Ileal Endogenous Amino Acid Losses in Growing Pigs Fed a Nitrogen-Free or Casein Diet.

The nitrogen-free diet (NFD) method for determining basal ileal endogenous losses (BEL) of amino acids (AA) has been associated with different metabolic abnormalities that can affect the accurate determination of BEL. Consequently, the use of highly digestible proteins has been suggested. This study aimed to determine the metabolic status and BEL of AA in pigs fed either an NFD or a casein (CAS) diet. Eight cannulated, castrated male pigs (39.8 kg) were randomly assigned to a 2 × 2 crossover design. An NFD diet based on corn starch, dextrose, cellulose, oil, vitamins and minerals was used. The CAS diet was equivalent, but 18% of the corn starch was replaced with casein. Pigs were fed one of the diets for a 7-day period, and blood samples were collected at the beginning and end of each period to determine plasma metabolites. Ileal digesta samples were collected on Days 6 and 7 to estimate the BEL of the AA. Results indicated that plasma albumin was significantly higher (p < 0.05) in pigs fed the CAS diet, whereas creatinine and LDL levels were higher (p < 0.03) in pigs fed the NFD. No significant differences were observed in the levels of other plasma metabolites. The BEL of protein did not differ between diets. However, in pigs fed the CAS diet, the BEL of glutamic acid, aspartic acid, serine, glycine, histidine, threonine, alanine, tyrosine and valine significantly increased (p < 0.05), while isoleucine showed a tendency to increase (p = 0.06). In conclusion, NFD did not significantly affect energy and lipid metabolism in pigs. However, the decrease in albumin synthesis and increase in plasma creatinine levels indicate that pigs fed NFD have a negative protein balance, affecting the estimation of the BEL of AA. Therefore, it is essential to consider the metabolic state of animals when estimating the BEL of AA.

Comparative Study on the Proximate Composition and Amino Acid Levels in Chanterelle (Cantharellus cibarius) and Wood Ear (Auricularia auricula) Mushroom Samples

Mushrooms have been consumed by mankind for millennia. They are macrofungi with a distinctive fruiting body which can be hypogeous or epigeous, large enough to be seen with unaided eyes. They are not widely consumed due to lack of information on its nutritive value. Therefore, this research was carried out to compare the proximate gross energy composition as well as amino acids levels in two selected edible mushrooms (Cantharellus cibarius and Auricularia auricula). Fully matured species of Chanterelle mushroom (Cantherellus cibarius) and Wood ear mushroom (Auricularia auricula) were collected from different parts of Southern and Northern Cross River; Ikom and Bekwara precisely. The collected samples were air dried for 5 days and then stored in transparent polythene bag for analysis. The dried and stored mushroom were pounded to powdered form and then subjected to amino acid analysis using isocratic HPLC and proximate analysis for proximate composition using the standard methods of Association of Official Analytical Chemist (AOAC). The results of this research showed that chanterelle mushroom has high concentration of amino acids compared to Wood ear mushroom. However, there was significant differences (p&lt;0.05) in the levels of isoleucine in both mushrooms. There were no significant differences in the proximate composition and gross energy levels of both mushroom species. Some of the amino acids detected in both mushrooms were: methionine, threonine, isoleucine, leucine, phenylalanine, valine, tryptophan, histidine, arginine, aspartic acid, glycine, alanine and glutamic acid. Based on the findings of this study, the two edible mushrooms were observed to have appreciable levels of gross energy and amino acids. However, Chanterelle mushroom had higher protein composition than wood ear. Hence, it can be concluded that Chanterelle mushroom has greater nutritive value and more suitable for consumption.

Construction of Chiral Covalent Organic Frameworks Through a Linker Decomposition Chiral Induction Strategy for Circularly Polarized Light Detection

AbstractExploring new strategies for construction of chiral covalent organic frameworks (COFs) is of paramount importance yet remains a challenge. Herein, we report the rational design and construction of chiral COFs through a linker decomposition chiral induction (LDCI) strategy. Three pairs of azine‐linked chiral COFs are successfully synthesized by the condensation reactions of C3‐symmetric 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzaldehyde (Tz) with flexible chiral dihydrazide linkers derived from malic acid, aspartic acid and tartaric acid, respectively. Remarkably, upon complete or partial decomposition from flexible chiral dihydrazides to hydrazine during COF synthesis, the homochirality of these COFs, originating from the single‐handedness conformation of propeller‐like Tz cores, is well preserved. Such a stereoselective chiral memory realized via the LDCI strategy is confirmed by time‐dependent powder X‐ray diffraction (PXRD), Fourier transform infrared (FT‐IR) and diffuse reflectance circular dichroism (DRCD). Moreover, the resultant azine‐linked chiral COFs are used as the active materials to fabricate photodetectors to directly distinguish circularly polarized light (CPL), showing impressive recognition performances on the identification of left‐handed circularly (LHC) and right‐handed circularly (RHC) polarized lights. Notably, the residual undecomposed flexible chiral linkers within the COFs are found to be conducive to improving the polarization discrimination ratio. This work highlights LDCI as a new and effective strategy for constructing homochiral COFs with promising future in chiral optical application.

Bone-Targeted Fluoropeptide Nanoparticle Inhibits NF-κB Signaling to Treat Osteosarcoma and Tumor-Induced Bone Destruction.

Osteosarcoma is a malignant bone cancer usually characterized by symptoms of bone loss due to pathologically enhanced osteoclast activity. Activated osteoclasts enhance bone resorption and promote osteosarcoma cell progression by secreting various cytokines. Intercepting the detrimental interplay between osteoclasts and osteosarcoma cells is considered as an option for osteosarcoma treatment. Here, a bone-targeted fluoropeptide nanoparticle that can inhibit the nuclear factor kappa B (NF-κB) signaling in both osteoclasts and osteosarcoma to address the above issue is developed. The NF-κB essential modulator binding domain (NBD) peptide is conjugated with a fluorous tag to improve its proteolytic stability and intracellular penetration. The NBD peptide is efficiently delivered into cells after fluorination to induce apoptosis of osteocarcoma cells, and inhibits osteoclasts differentiation. The fluorous-tagged NBD peptide is further co-assembled with an oligo (aspartic acid) terminated fluoropeptide to form bone-targeted peptide nanoparticles for osteosarcoma treatment. The targeted nanoparticles efficiently inhibited tumor progression and osteosarcoma-induced bone destruction in vivo. This co-assembled fluoropeptide nanoplatform proposed in this study offers a promising approach for targeted and intracellular delivery of peptide therapeutics in the treatment of various diseases.

Enhancement of colour density and anthocyanin stability in pomegranate juice against 5-hydroxymethylfurfural at different concentrations by amino acid copigmentation during storage

This study investigated the effect of amino acid [aspartic acid (Asp), phenylalanine (Phe) and valine (Val)] copigmentation on pomegranate juice (PJ) anthocyanins in the presence of 5-hydroxymethylfurfural (HMF) at different concentrations (2.3–15.2 mg/L) during storage at 20°C. A decrease in stabilities of anthocyanin and colour density (CD) was observed at 5.2–8.2 mg HMF/L. However, 15.2 mg HMF/L prevented the decrease in anthocyanin stability. In this sample, copigmentation occurred when ratios of "cyanidin-3,5-diglucoside to HMF" and "cyanidin-3-glucoside to HMF" were 1.82–2.67 and 1.91–2.85, respectively. The highest reduction in HMF content resulted from addition of Val. As number of –CH3 groups in an amino acid increased, HMF reducing effect of amino acid increased. In PJ containing 8.2 mg HMF/L, Val provided the highest stabilities for individual anthocyanins, CD and hyperchromic effect (HE). Asp increased the stability of CD and HE in PJ containing 5.2 mg HMF/L, while Phe increased the stability of CD at a concentration of 15.2 mg HMF/L. Depending on the amount of HMF, the effect of adding amino acids to PJ to improve colour stability and reduce HMF content varies. Therefore, after determining the initial HMF content of PJ, the amino acid to be added to PJ should be decided.

Construction of Chiral Covalent Organic Frameworks Through a Linker Decomposition Chiral Induction Strategy for Circularly Polarized Light Detection

AbstractExploring new strategies for construction of chiral covalent organic frameworks (COFs) is of paramount importance yet remains a challenge. Herein, we report the rational design and construction of chiral COFs through a linker decomposition chiral induction (LDCI) strategy. Three pairs of azine‐linked chiral COFs are successfully synthesized by the condensation reactions of C3‐symmetric 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzaldehyde (Tz) with flexible chiral dihydrazide linkers derived from malic acid, aspartic acid and tartaric acid, respectively. Remarkably, upon complete or partial decomposition from flexible chiral dihydrazides to hydrazine during COF synthesis, the homochirality of these COFs, originating from the single‐handedness conformation of propeller‐like Tz cores, is well preserved. Such a stereoselective chiral memory realized via the LDCI strategy is confirmed by time‐dependent powder X‐ray diffraction (PXRD), Fourier transform infrared (FT‐IR) and diffuse reflectance circular dichroism (DRCD). Moreover, the resultant azine‐linked chiral COFs are used as the active materials to fabricate photodetectors to directly distinguish circularly polarized light (CPL), showing impressive recognition performances on the identification of left‐handed circularly (LHC) and right‐handed circularly (RHC) polarized lights. Notably, the residual undecomposed flexible chiral linkers within the COFs are found to be conducive to improving the polarization discrimination ratio. This work highlights LDCI as a new and effective strategy for constructing homochiral COFs with promising future in chiral optical application.

Application of metabolomics approach to investigate the flavor substance differences between triploid and diploid oysters (Crassostrea angulata)

Oysters, particularly Portuguese oyster (Crassostrea angulata), are highly valued for their nutritional and flavor qualities, making them important in global aquaculture. Triploid oysters have gained attention for maintaining higher meat quality year-round compared to diploids, but there is limited research on how ploidy affects their biochemical and flavor profiles. This study uses a non-targeted metabolomics approach, including gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS), to investigate flavor substance differences between triploid and diploid C. angulata. A total of 13 volatile compounds were identified in diploid oysters, while 28 were found in triploids. Significant upregulation of inosine, guanosine, L-aspartic acid, and taurine in triploids contributes to their enhanced flavor profile. Additionally, triploids showed higher nicotinamide concentrations, while diploids had increased 25-hydroxycholesterol. These findings highlight the advantages of triploid oysters in aquaculture for improved flavor and nutrition, supporting their potential for year-round production.

Comparative Study of Amino Acids in the Life Stages of Silkworm (Bombyx mori L.)

The silkworm (Bombyx mori L.) undergoes distinct life stages, including egg, larva (caterpillar), pupa (chrysalis), and adult moth(imago), each with specific physiological requirements. Amino acids are essential for the growth and development of the silkworm. In this study, we work in paper chromatography to compare the amino acid profiles in different life stages of the silkworm. Samples were collected from eggs, larvae, pupae, and adult moths. Amino acids were extracted and separated on chromatographic paper using a suitable solvent system. The developed chromatograms were analyzed to determine the relative concentrations of specific amino acids. Our results revealed variations in the amino acid composition across the life stages. The amino acids such as glycine, methionine, leucine, and aspartic acid were common in all life stages of silkworms. These differences may be attributed to the physiological changes associated with metamorphosis and reproduction in adult silkworms. Overall, this study provides valuable insights into the dynamic changes in amino acid profiles during the life stages of silkworms, highlighting the importance of amino acids in their growth, development, and silk production. And, this study demonstrates the utility of paper chromatography as a cost-effective and reliable method for analyzing amino acid composition in complex biological samples, providing valuable insights into the nutritional dynamics of the silkworm lifecycle.