Distribution Of Amino Acids Research Articles

Aqueous breakdown of aspartate and glutamate to n-ω-amino acids on the parent bodies of carbonaceous chondrites and asteroid Ryugu

Amino acids in carbonaceous chondrites may have seeded the origin of life on Earth and possibly elsewhere. Recently, the return samples from a C-type asteroid Ryugu were found to contain amino acids with a similar distribution to Ivuna-type CI chondrites, suggesting the potential of amino acid abundances as molecular descriptors of parent body geochemistry. However, the chemical mechanisms responsible for the amino acid distributions remain to be elucidated particularly at low temperatures (<50°C). Here, we report that two representative proteinogenic amino acids, aspartic acid and glutamic acid, decompose to β-alanine and γ-aminobutyric acid, respectively, under simulated geoelectrochemical conditions at 25°C. This low-temperature conversion provides a plausible explanation for the enrichment of these two n-ω-amino acids compared to their precursors in heavily aqueously altered CI chondrites and Ryugu’s return samples. The results suggest that these heavily aqueously altered samples originated from the water-rich mantle of their water/rock differentiated parent planetesimals where protein α-amino acids were decomposed.

Molecular insights into substrate promiscuity of CotA laccase catalyzing lignin-phenol derivatives

CotA laccases are multicopper oxidases known for promiscuously oxidizing a broad range of substrates. However, studying substrate promiscuity is limited by the complexity of electron transfer (ET) between substrates and laccases. Here, a systematic analysis of factors affecting ET including electron donor acceptor coupling (ΗDA), driving force (ΔG) and reorganization energy (λ) was done. Catalysis rates of syringic acid (SA), syringaldehyde (SAD) and acetosyringone (AS) (kcat(SAD) > kcat(SA) > kcat(AS)) are not entirely dependent on the ability to form phenol radicals indicated by ΔG and λ calculated by Density Functional Theory (SA < SAD ≈ AS). In determined CotA/SA and CotA/SAD structures, SA and SAD bound at 3.9 and 3.7 Å away from T1 Cu coordinating His419 ensuring a similar ΗDA. Abilities of substrate to form phenol radicals could mainly account for difference between kcat(SAD) and kcat(SA). Furthermore, substrate pocket is solvent exposed at the para site of substrate's phenol hydroxyl, which would destabilize binding of AS in the same orientation and position resulting in low kcat. Our results indicated shallow partially covered binding site with propensity of amino acids distribution might help CotA discriminate lignin-phenol derivatives. These findings give new insights for developing specific catalysts for industrial application.

Feature selection for effective prediction of SARS-COV-2 using machine learning.

With rise in variants of SARS-CoV-2, it is necessary to classify the emerging SARS-CoV-2 for early detection and thereby reduce human transmission. Genomic and proteomic information have less frequently been used for classifying in a machine learning (ML) approach for detection of SARS-CoV-2. With this aim we used nucleoprotein and viral proteomic evolutionary information of SARS-CoV-2 along with the charge and basicity distribution of amino acids from various strains of SARS-CoV-2 to generate a disease severity model based on ML. All sequence and clinical data were obtained from GISAID. Proteomic level calculations were added to comprise the dataset. The training set was used for feature selection. Select K- Best feature selection method was employed which was cross validated with testing set and performance evaluated. Delong's test was also done. We also employed BIRCH clustering on SARS-CoV-2 for clustering the strains. Out of six ML models four were successful in training and testing. Extra Trees algorithm generated a micro-averaged F1-score of 74.2% and a weighted averaged area under the receiver operating characteristic curve (AUC-ROC) score of 73.7% with multi-class option. The feature selection set to 5, enhanced the ROC AUC from 73.7 to 76.4%. Accuracy of the selected model of 86.9% was achieved. The unique features identified in the ML approach was able to classify disease severity into classes and had potential for predicting risk in newer variants.

Proteomes reveal metabolic capabilities of Yarrowia lipolytica for biological upcycling of polyethylene into high-value chemicals.

Sustainable processes for biological upcycling of plastic wastes in a circular bioeconomy are needed to promote decarbonization and reduce environmental pollution due to increased plastic consumption, incineration, and landfill storage. Strain characterization and proteomic analysis revealed the robust metabolic capabilities of Yarrowia lipolytica to upcycle polyethylene into high-value chemicals. Significant proteome reallocation toward energy and lipid metabolisms was required for robust growth on hydrocarbons with n-hexadecane as the preferential substrate. However, an apparent over-investment in these same categories to utilize complex depolymerized plastic (DP) oil came at the expense of protein biosynthesis, limiting cell growth. Taken together, this study elucidates how Y. lipolytica activates its metabolism to utilize DP oil and establishes Y. lipolytica as a promising host for the upcycling of plastic wastes.

Solid-State Single-Molecule Sensing with the Electronic Life-Detection Instrument for Enceladus/Europa (ELIE).

Growing evidence of the potential habitability of Ocean Worlds across our solar system is motivating the advancement of technologies capable of detecting life as we know it-sharing a common ancestry or physicochemical origin with life on Earth-or don't know it, representing a distinct emergence of life different than our one known example. Here, we propose the Electronic Life-detection Instrument for Enceladus/Europa (ELIE), a solid-state single-molecule instrument payload that aims to search for life based on the detection of amino acids and informational polymers (IPs) at the parts per billion to trillion level. As a first proof-of-principle in a laboratory environment, we demonstrate the single-molecule detection of the amino acid L-proline at a 10 μM concentration in a compact system. Based on ELIE's solid-state quantum electronic tunneling sensing mechanism, we further propose the quantum property of the HOMO-LUMO gap (energy difference between a molecule's highest energy-occupied molecular orbital and lowest energy-unoccupied molecular orbital) as a novel metric to assess amino acid complexity. Finally, we assess the potential of ELIE to discriminate between abiotically and biotically derived α-amino acid abundance distributions to reduce the false positive risk for life detection. Nanogap technology can also be applied to the detection of nucleobases and short sequences of IPs such as, but not limited to, RNA and DNA. Future missions may utilize ELIE to target preserved biosignatures on the surface of Mars, extant life in its deep subsurface, or life or its biosignatures in a plume, surface, or subsurface of ice moons such as Enceladus or Europa. One-Sentence Summary: A solid-state nanogap can determine the abundance distribution of amino acids, detect nucleic acids, and shows potential for detecting life as we know it and life as we don't know it.

Proteomics and NGS Analysis of Induced Myeloid Leukemia Cells

Abstract: Induced myeloid leukemia cells have emerged as critical models for unraveling intricate molecular mechanisms of leukemogenesis. Integration of proteomics and Next-Generation Sequencing (NGS) analyses has yielded profound insights. Mcl1's significance in tumorigenesis and therapeutic resistance highlights Mcl-1 inhibitors' promise as anticancer agents. A selectively designed macrocyclic compound for Mcl-1 with high affinity, currently in clinical development, signifies a milestone in precision therapy. Activation of the Bak-dependent mitochondrial apoptotic pathway in acute myeloid leukemia offers novel insights into apoptotic regulation and potential interventions. Strikingly, complete tumor regression was achieved in diverse myeloma and acute myeloid leukemia models with a single tolerated dose of the compound, as monotherapy or combined with bortezomib or venetoclax, showcasing its therapeutic potential. Structural analyses through PyMOL and RasMol reveal intricate protein architecture, informing amino acid distributions, topology, and electrostatic profiles. These insights underpin understanding of protein functionality and intermolecular interactions. Simultaneously, multi-omics strategies, spanning genomics, epigenomics, transcriptomics, and proteomics, illuminate induced myeloid leukemia cells. These approaches uncover recurrent mutations, copy number variations, and fusion genes driving leukemogenesis. Epigenetic modifications, notably DNA methylation and chromatin remodeling, modulate gene expression in leukemic contexts.Together, these efforts underscore the significance of integrating diverse omics layers to decode leukemic transformation intricacies. The findings offer therapeutic prospects and insights into disease progression, fostering nuanced treatments across oncogenic landscapes beyond myeloid leukemia.

Methane hydrate formation in clay mineral suspensions containing glycine: Experimental study and molecular dynamics simulation

Understanding the effects of clay minerals and amino acids on methane hydrate (MH) formation is essential for elucidating the occurrence of MH in marine sediments. In this study, kinetic experiments and molecular dynamics simulations of MH formation in montmorillonite and kaolinite systems with the presence of glycine were investigated. The experimental results showed that the addition of 5 wt% montmorillonite and 5 wt% kaolinite inhibited and promoted MH formation, respectively. Adding 1.5 wt% glycine to the montmorillonite suspension shortened the nucleation time and reduced the amount of MH; it also weakened the facilitating effect of the kaolinite suspension. The simulation results showed MH nucleation in the bulk solution due to the hydration properties of Ca2+ on the external surface of montmorillonite. However, the addition of glycine reduced the inhibitory effect of Ca2+ on MH formation due to the electrostatic interaction between the Ca2+ and COO– groups. Adsorbed methane molecules on the kaolinite siloxane surface formed clathrate-like structures. In addition, glycine also abnormally incorporated into the MH structure to inhibit MH nucleation. These findings imply that the clay mineral had a significant effect on the distribution of amino acids, causing the formation of MH in clay mineral suspension to be different from pure water. Therefore, these interactions should be fully considered when studying the occurrence mechanism of natural gas hydrate when clay minerals and amino acids coexist in marine sediments.

Compounds composition of pollen tubes of Scots pine (Pinus sylvestris L.).

The aim of this research was to study the composition of pollen tubes of Scots pine (Pinus sylvestris L.). Pollen cultivation on deionized distilled water excluded the potential influence of the cultivation medium on the pollen tube growth and development. The fluorescent study indicated a gradual distribution of chemical compounds along the length of the tube. It was shown that the protoplast apical zone and the parietal layer near the tube's tip are most likely actively involved in the ion transport regulation in the growing pollen tube. The callose synthesis in the tip of matured pine tube completed the first stage of its active growth. Significant differences and pH gradients at the nucleus region and the parietal layer of the tube wall indicate that H+ gradient is the direct driving force of vesicle transport and can regulate the growth of pollen tubes. The distribution of amino acids, RNA, proteins and lipids was uniform throughout the length of the pine pollen tube. The content of amino acids, RNA, DNA and proteins slightly increased near the cell nucleus and drastically increased in the apical zone. At the very tip of the tube, a slight increase in the concentration of polysaccharides and a significant decrease in the content of amino acids, RNA, DNA, proteins and lipids were detected.

Genetic architecture of tuber-bound free amino acids in potato and effect of growing environment on the amino acid content

Free amino acids in potato tubers contribute to their nutritional value and processing quality. Exploring the natural variation in their accumulation in tubers across diverse genetic backgrounds is critical to potato breeding programs aiming to enhance or partition their distribution effectively. This study assessed variation in the tuber-bound free amino acids in a diversity panel of tetraploid potato clones developed and maintained by the Texas A&M Potato Breeding Program to explore their genetic basis and to obtain genomic-estimated breeding values for applied breeding purposes. Free amino acids content was evaluated in tubers of 217 tetraploid potato clones collected from Dalhart, Texas in 2019 and 2020, and Springlake, Texas in 2020. Most tuber amino acids were not affected by growing location, except histidine and proline, which were significantly lower (− 59.0%) and higher (+ 129.0%), respectively, at Springlake, Texas (a location that regularly suffers from abiotic stresses, mainly high-temperature stress). Single nucleotide polymorphism markers were used for genome-wide association studies and genomic selection of clones based on amino acid content. Most amino acids showed significant variations among potato clones and moderate to high heritabilities. Principal component analysis separated fresh from processing potato market classes based on amino acids distribution patterns. Genome-wide association studies discovered 33 QTL associated with 13 free amino acids. Genomic-estimated breeding values were calculated and are recommended for practical potato breeding applications to select parents and advance clones with the desired free amino acid content.

Comprehensive landscape of the T and B-cell repertoires of newly diagnosed gestational diabetes mellitus

This study conducted a high-throughput sequencing analysis of the T- and B- repertoires in the newly diagnosed GDM patients and evaluated the association between abnormal adaptive immunity and GDM. The unique TCR CDR3 clonotypes were mildly decreased in GDM patients, and the similarity of TCR V-J distributions was higher in the GDM group. Moreover, the usages of the V gene and V-J pair and the frequency distributions of some CDR3 amino acids (AAs) both in BCR and TCR were significantly different between groups. Moreover, the cytokines including IL-4, IL-6, IFN-γ and IL-17A were synchronously elevated in the GDM cases. Our findings provide a comprehensive view of BCR and TCR repertoires at newly diagnosed GDM patients, revealing the mild reduction in unique TCRB CDR3 sequences and slight alteration of the V gene, V-J combination and CDR3 (AA) usages of BCR and TCR. This work provides deep insight into the mechanism of maternal adaptive immunity in GDM and provides novel diagnostic biomarkers and potential immunotherapy targets for GDM.

MutBLESS: A tool to identify disease-prone sites in cancer using deep learning

Understanding the molecular basis and impact of mutations at different stages of cancer are long-standing challenges in cancer biology. Identification of driver mutations from experiments is expensive and time intensive. In the present study, we collected the data for experimentally known driver mutations in 22 different cancer types and classified them into six categories: breast cancer (BRCA), acute myeloid leukaemia (LAML), endometrial carcinoma (EC), stomach cancer (STAD), skin cancer (SKCM), and other cancer types which contains 5747 disease prone and 5514 neutral sites in 516 proteins. The analysis of amino acid distribution along mutant sites revealed that the motifs AAA and LR are preferred in disease-prone sites whereas QPP and QF are dominant in neutral sites. Further, we developed a method using deep neural networks to predict disease-prone sites with amino acid sequence-based features such as physicochemical properties, secondary structure, tri-peptide motifs and conservation scores. We obtained an average AUC of 0.97 in five cancer types BRCA, LAML, EC, STAD and SKCM in a test dataset and 0.72 in all other cancer types together. Our method showed excellent performance for identifying cancer-specific mutations with an average sensitivity, specificity, and accuracy of 96.56 %, 97.39 %, and 97.64 %, respectively. We developed a web server for identifying cancer-prone sites, and it is available at https://web.iitm.ac.in/bioinfo2/MutBLESS/index.html. We suggest that our method can serve as an effective method to identify disease-prone sites and assist to develop therapeutic strategies.

Depth of Sequencing Plays a Determining Role in the Characterization of Phage Display Peptide Libraries by NGS

Next-generation sequencing (NGS) has raised a growing interest in phage display research. Sequencing depth is a pivotal parameter for using NGS. In the current study, we made a side-by-side comparison of two NGS platforms with different sequencing depths, denoted as lower-throughput (LTP) and higher-throughput (HTP). The capacity of these platforms for characterization of the composition, quality, and diversity of the unselected Ph.D.TM-12 Phage Display Peptide Library was investigated. Our results indicated that HTP sequencing detects a considerably higher number of unique sequences compared to the LTP platform, thus covering a broader diversity of the library. We found a larger percentage of singletons, a smaller percentage of repeated sequences, and a greater percentage of distinct sequences in the LTP datasets. These parameters suggest a higher library quality, resulting in potentially misleading information when using LTP sequencing for such assessment. Our observations showed that HTP reveals a broader distribution of peptide frequencies, thus revealing increased heterogeneity of the library by the HTP approach and offering a comparatively higher capacity for distinguishing peptides from each other. Our analyses suggested that LTP and HTP datasets show discrepancies in their peptide composition and position-specific distribution of amino acids within the library. Taken together, these findings lead us to the conclusion that a higher sequencing depth can yield more in-depth insights into the composition of the library and provide a more complete picture of the quality and diversity of phage display peptide libraries.

Establishment of Age Specific Reference Interval for Aminoacids and Acylcarnitine in Dried Blood Spot by Tandem Mass Spectrometry.

The Extended Screening for Inborn Errors of Metabolism is done for aminoacidopathies, fatty acid oxidation disorders and organic acid disorders. In a single dried blood spot, the tandem mass spectrometry is capable of measuring multiple analytes like amino acids, acylcarnitines, nucleosides, succinylacetone and lysophosphatidylcholines. This study was proposed to establish age specific reference internal for aminoacids and acylcartinitine in dried blood spot by tandem mass spectrometry. A total of 480 apparently healthy children were enrolled for the study and sub classified into four groups as follows: Group A: 0-1month, Group B: 1month-1year, Group C: 1-5year and Group D: 5-12years each having 120 participants. Sample size were calculated as per CLSI approved guidelines. Tables 1 and 2 presents the age-specific percentile distribution of aminoacids and acylcarnitines established from healthy subjects as per rank-based method recommended by the IFCC and CLSI. Tables 3, 4 and 5 presents the cut-off values of primary and secondary marker/ratios for screening of aminoacidopathies, fatty acid oxidation disorders and organic acid disorders respectively. As a general principle, the interpretation of extended newborn screening results should be based on age specific cut-off established by the laboratory for primary analyte concentration and secondary analyte concentration/ ratios. This study was useful in establishing age specific cut-off values for various amino acids and acylcarnitines in South Indian population. [Table: see text] [Table: see text] [Table: see text] [Table: see text] [Table: see text].

Tissue Distribution and Excretion of Alpha-aminoisobutyric Acid in the Rat: I. Effect of Dietary Protein Level and Composition

The nature of the diet fed to rats greatly influenced the distribution ratio of injected 1-C14-α-aminoisobutyric acid (AIB) between tissues and serum, as well as its pattern of urinary excretion. An increased concentration of AIB was observed in the liver of animals maintained with deficient diets while at the same time the non-hepatic tissues showed a decreased concentrative capacity. The levels of dietary protein ranging from a protein-free diet to as high as 54% casein, affected very significantly the pattern of urinary excretion and the net AIB retention, but did not affect to any great extent, the relative tissue distribution. At high protein levels the urinary loss of AIB was greatly enhanced. The large amount of stored AIB in the tissues of rats fed low protein diets over an extended period was immediately mobilized and excreted when the protein content of the diet was suddenly increased. The importance of taking into account the nature, as well as the amount, of the diet consumed during studies on amino acid distribution is stressed.

Extraterrestrial amino acids and amines identified in asteroid Ryugu samples returned by the Hayabusa2 mission

The hot water and acid extracts of two different Ryugu samples collected by the Hayabusa2 mission were analyzed for the presence of aliphatic amines and amino acids. The abundances and relative distributions of both classes of molecules were determined, as well as the enantiomeric compositions of the chiral amino acids. The Ryugu samples studied here were recovered from sample chambers A and C, which were composed of surface material, and a combination of surface and possible subsurface material, respectively. A total of thirteen amino acids were detected and quantitated in these samples, with an additional five amino acids that were tentatively identified but not quantitated. The abundances of four aliphatic amines identified in the Ryugu samples were also determined in the current work. Amino acids were observed in the acid hydrolyzed and unhydrolyzed hot water extracts of asteroid Ryugu regolith using liquid chromatography with UV fluorescence detection and high-resolution mass spectrometry. Conversely, aliphatic amines were only analyzed in the unhydrolyzed hot water Ryugu extracts. Two- to six-carbon (C2-C6) amino acids with individual abundances ranging from 0.02 to 15.8 nmol g−1, and one- to three-carbon (C1-C3) aliphatic amines with individual abundances from 0.05 to 34.14 nmol g−1, were found in the hot water extracts. Several non-protein amino acids that are rare in biology, including β-amino-n-butyric acid (β-ABA) and β-aminoisobuytric acid (β-AIB), were racemic or very nearly racemic, thus indicating their likely abiotic origins. Trace amounts of select protein amino acids that were enriched in the l-enantiomer may indicate low levels of terrestrial amino acid contamination in the samples. However, the presence of elevated abundances of free and racemic alanine, a common protein amino acid in terrestrial biology, and elevated abundances of the predominately free and racemic non-protein amino acids, β-ABA and β-AIB, indicate that many of the amino acids detected in the Ryugu water extracts were indigenous to the samples. Although the Ryugu samples have been found to be chemically similar to CI type carbonaceous chondrites, the measured concentrations and relative distributions of amino acids and aliphatic amines in Ryugu samples were notably different from those previously observed for the CI1.1 carbonaceous chondrite, Orgueil. This discrepancy could be the result of differences in the original chemical compositions of the parent bodies and/or alteration conditions, such as space weathering. In addition to α-amino acids that could have been formed by Strecker cyanohydrin synthesis during a low temperature aqueous alteration phase, β-, γ-, and δ-amino acids, including C3 – C5 straight-chain n-ω-amino acids that are not formed by Strecker synthesis, were also observed in the Ryugu extracts. The suite of amino acids measured in the Ryugu samples indicates that multiple amino acid formation mechanisms were active on the Ryugu parent body. The analytical techniques used here are well-suited to search for similar analytes in asteroid Bennu material collected by the NASA OSIRIS-REx mission scheduled for Earth return in September 2023.

The Fishy Off-Odor Removal and Umami Enhancing Effect of Enzymatic Hydrolysis of Fish By-Products by Proteases

ABSTRACT The aim was to study the changes in flavor compounds hydrolyzed by different proteases in fish soup boiled with fish scraps The odor compounds were extracted by solid-phase microextraction (SPME) and analyzed by two-dimensional comprehensive gas chromatography-olfactometry-mass spectrometry (GC×GC-O-MS). The state of the distribution of free amino acids, 5’-nucleotides, peptides and equivalent umami concentration (EUC) were investigated. It was found that enzymatic hydrolysis significantly reduced off-flavor compounds, and the umami taste increased significantly. The synergistic effect between FlavourzymeTM and ProtamexTM (F-P) made the flavor of enzymatic hydrolysis better than that of other enzymes.

Quantitative study of the dynamics and energetics of peptide-lipid membrane interaction using coarse-grained molecular dynamics simulations.

Peptide-lipid membrane interactions are fundamental in molecular biology. A quantitative description, at single amino acid level, of the interaction of peptides with lipid membranes is essential in understanding the subtle microscopic mechanisms of membrane protein partitioning and folding. Here we demonstrate that long time-scale coarse-grained molecular dynamics (CG-MD) simulations can be used effectively to study both the conformational dynamics and the energetics of peptides and peripheral membrane proteins interacting with lipid bilayers. First, the penetration depth distribution of individual amino acids, obtained from tens of µs long CG-MD trajectories, provide a detailed description of the binding of the peptide to the lipid membrane. Second, the free energy profile (potential of mean force or PMF), as a function of the peptide-lipid membrane separation, can be calculated using the CG umbrella sampling method. The features of the PMF appear to be consistent with existing experimental results. Furthermore, we find that repeated CG-MD simulations that take into account the microscopic inhomogeneities of the system lead to a stochastic ensemble of PMFs that can be used to identify the dominant dissociation pathways of the peptide from the lipid bilayer. Third, the reconstructed PMF can be used to (i) interpret the peptide-lipid membrane dissociation force distribution measured in AFM force spectroscopy experiments, and (ii) infer the corresponding dissociation rate. We apply the above approach to investigate two exemplary systems, namely: (1) three Wimley-White pentapeptides (Ac-WLXLL, with guest residues X = R,I and L) interacting with POPC and POPG lipid bilayers, and (2) the extreme N-terminus (SecA2-11) of the SecA peripheral membrane protein from E. coli, interacting with a POPC bilayer.

Determinants of associations between codon and amino acid usage patterns of microbial communities and the environment inferred based on a cross-biome metagenomic analysis

Codon and amino acid usage were associated with almost every aspect of microbial life. However, how the environment may impact the codon and amino acid choice of microbial communities at the habitat level is not clearly understood. Therefore, in this study, we analyzed codon and amino acid usage patterns of a large number of environmental samples collected from diverse ecological niches. Our results suggested that samples derived from similar environmental niches, in general, show overall similar codon and amino acid distribution as compared to samples from other habitats. To substantiate the relative impact of the environment, we considered several factors, such as their similarity in GC content, or in functional or taxonomic abundance. Our analysis demonstrated that none of these factors can fully explain the trends that we observed at the codon or amino acid level implying a direct environmental influence on them. Further, our analysis demonstrated different levels of selection on codon bias in different microbial communities with the highest bias in host-associated environments such as the digestive system or oral samples and the lowest level of selection in soil and water samples. Considering a large number of metagenomic samples here we showed that microorganisms collected from similar environmental backgrounds exhibit similar patterns of codon and amino acid usage irrespective of the location or time from where the samples were collected. Thus our study suggested a direct impact of the environment on codon and amino usage of microorganisms that cannot be explained considering the influence of other factors.

Study on the preparation process of quinoa anti-hypertensive peptide and its stability.

Quinoa seeds are a food resource rich in protein, vitamins, minerals, and other functional components such as polyphenols, polysaccharides, and saponins. The seeds have become favored by modern consumers due to being gluten-free and featuring a high protein content. This study focused on the preparation of quinoa peptides by short-time enzymatic-assisted fermentation. Quinoa flour (QF) was mixed with water in a certain ratio before being enzymatically digested with 0.5% amylase and 0.1% lipase for 6 h. Then, 16 bacterial taxa were used for fermentation, respectively. The peptide content in the resulting fermentation broths were determined by the biuret method. The dominant taxon was then identified and the peptide content, amino acid distribution, and molecular weight distribution of the prepared quinoa peptides were analyzed. Further, the temperature, pH, metal ions, organic solvents, ion concentration, and anti-enzyme stability of the quinoa anti-hypertensive peptides of different molecular weights after fermentation with the dominant taxon were investigated. Finally, the inhibitory activity of fermented quinoa peptides on bacteria was studied. The results show that the peptide content of the fermentation broth reached 58.72 ± 1.3% at 40 h of fermentation with Lactobacillus paracasei and the molecular weights of the hydrolyzed quinoa peptides were mainly distributed below 2 kDa by polyacrylamide gel. The Angiotensin Converting Enzyme (ACE) inhibition and peptide retention of the 0-3 kDa quinoa peptides were screened to be high and stable. At the same time, the inhibitory activity of quinoa peptide after fermentation on E. coli was obvious. This study provides a theoretical basis for further research on quinoa peptide and its application in industrial production, and also lays a foundation for the later application of polypeptides in new food and chemical products.

Visualized analysis of amino acids and organic acids in wheat caryopsis in response to multigenerational effects of elevated atmospheric CO2 concentration

The response of wheat to elevated atmospheric CO2 concentration (e[CO2]) within a single generation is being cumulatively studied, but multigenerational effects of e[CO2] on wheat is largely unknown. In this study, the emerging spatially resolved metabolomics was used to visualize the spatial distributions of amino acids and organic acids in wheat caryopsis exposed to multigenerational e[CO2]. These results showed that nine kinds of amino acids and three kinds of organic acids exhibited embryo-distribution pattern in wheat caryopsis under sequential atmospheric CO2 concentration (a[CO2]). Additionally, e[CO2] can induce nonuniformly spatial distribution of amino acids and organic acids. Further inspection of the differential accumulation of amino acids in embryo/endosperm under multigenerational e[CO2] exposure indicated that the abundance of valine, glutamine, glutamic acid and histidine in embryo was decreased by multigenerational e[CO2] exposure, whereas abundance of lysine, aspartic acid and glutamic acid in endosperm showed different trends. Multigenerational e[CO2] exposure decreased the abundance of ascorbic acid and cis-aconitic acid, regardless of regions, while increased the abundance of malic acid in endosperm. It was suggested that the long-term e[CO2] cause inconsistent changes in embryo and endosperm, which may lead to potential impacts on human dietary health and crop offspring vigor.