Hydrolysable Amino Acids Research Articles

Binding of Th, Pa, Pb, Po and Be radionuclides to marine colloidal macromolecular organic matter

To study the binding mechanisms of radionuclides to organic moieties in colloidal organic matter (COM), marine colloids (1kDa–0.2μm) were isolated by cross-flow ultrafiltration from seawater of the west Pacific Ocean and the northern Gulf of Mexico. For the same purpose, exopolymeric substances (EPS) produced by laboratory-cultured diatoms were collected as well. In our study areas, colloidal organic carbon (COC) concentrations ranged from 6.5 to 202μg-C/L in the Pacific Ocean, and were 808μg-C/L in the Gulf of Mexico. The COM compositions (organic carbon, organic nitrogen, proteins, total hydrolysable amino acids, total polysaccharides, uronic acids, hydroxamate siderophores, hydroquinone) were quantified to examine the relationships between partition coefficients (Kc) of five different radionuclides, 234Th, 233Pa, 210Pb, 210Po and 7Be, and concentration ratios to COC of individual chelating biomolecules that could potentially act as a chelating moiety. The range of partition coefficients (Kc, reported as logKc) of radionuclides between water and the different colloidal materials was 5.12 to 5.85 for 234Th, 5.19 to 6.01 for 233Pa, 4.21 to 4.85 for 210Pb, 4.87 to 5.68 for 210Po, and 4.49 to 4.92 for 7Be, similar to values previously reported for lab and field determinations under different particle concentrations. While any relationship obtained between Kc and abundance of specific moieties could not be taken as proving the existence of colloidal organic binding ligands for the different radionuclides, it could suggest possible organic moieties involved in the scavenging of these natural radionuclides. Together with results from isoelectric focusing of radiolabeled COM, we conclude that binding to different biomolecules is nuclide-specific, with colloidal hydroxamate siderophoric moieties being important for the binding of Th and Pa radionuclides. Hydroquinones/quinone (HQ/Q) facilitated redox and chelation reactions seem to be involved in the binding of Pa and Be. However, the actual mechanisms are not clear. Individual amino acids, proteins, total polysaccharides and uronic acids did not yield significant relationships with logKc values of the different radionuclides. Nonetheless, our results provide new insights into the relative importance of different potential ligand moieties in COM in the binding and possible scavenging of specific radionuclides in the ocean.

The genome of the myxosporean Thelohanellus kitauei shows adaptations to nutrient acquisition within its fish host.

Members of Myxozoa, a parasitic metazoan taxon, have considerable detrimental effects on fish hosts and also have been associated with human food-borne illness. Little is known about their biology and metabolism. Analysis of the genome of Thelohanellus kitauei and comparative analysis with genomes of its two free-living cnidarian relatives revealed that T. kitauei has adapted to parasitism, as indicated by the streamlined metabolic repertoire and the tendency toward anabolism rather than catabolism. Thelohanellus kitauei mainly secretes proteases and protease inhibitors for nutrient digestion (parasite invasion), and depends on endocytosis (mainly low-density lipoprotein receptors-mediated type) and secondary carriers for nutrient absorption. Absence of both classic and complementary anaerobic pathways and gluconeogenesis, the lack of de novo synthesis and reduced activity in hydrolysis of fatty acids, amino acids, and nucleotides indicated that T. kitauei in this vertebrate host–parasite system has adapted to inhabit a physiological environment extremely rich in both oxygen and nutrients (especially glucose), which is consistent with its preferred parasitic site, that is, the host gut submucosa. Taking advantage of the genomic and transcriptomic information, 23 potential nutrition-related T. kitauei-specific chemotherapeutic targets were identified. This first genome sequence of a myxozoan will facilitate development of potential therapeutics for efficient control of myxozoan parasites and ultimately prevent myxozoan-induced fish-borne illnesses in humans.

Electrophoretic Extraction and Proteomic Characterization of Proteins Buried in Marine Sediments

Proteins are the largest defined molecular component of marine organic nitrogen, and hydrolysable amino acids, the building blocks of proteins, are important components of particulate nitrogen in marine sediments. In oceanic systems, the largest contributors are phytoplankton proteins, which have been tracked from newly produced bloom material through the water column to surface sediments in the Bering Sea, but it is not known if proteins buried deeper in sediment systems can be identified with confidence. Electrophoretic gel protein extraction methods followed by proteomic mass spectrometry and database searching were used as the methodology to identify buried phytoplankton proteins in sediments from the 8–10 cm section of a Bering Sea sediment core. More peptides and proteins were identified using an SDS-PAGE tube gel than a standard 1D flat gel or digesting the sediment directly with trypsin. The majority of proteins identified correlated to the marine diatom, Thalassiosira pseudonana, rather than bacterial protein sequences, indicating an algal source not only dominates the input, but also the preserved protein fraction. Abundant RuBisCO and fucoxanthin chlorophyll a/c binding proteins were identified, supporting algal sources of these proteins and reinforcing the proposed mechanisms that might protect proteins for long time periods. Some preserved peptides were identified in unexpected gel molecular weight ranges, indicating that some structural changes or charge alteration influenced the mobility of these products during electrophoresis isolation. Identifying buried photosystem proteins suggests that algal particulate matter is a significant fraction of the preserved organic carbon and nitrogen pools in marine sediments.

Production of chitin and bioactive materials from Black tiger shrimp (Penaeus monodon) shell waste by the treatment of bacterial protease cocktail.

The main objective of this study was to obtain chitin in pure form from a new crustacean waste material for industrial applications. Black tiger shrimp shell wastes are a rich source of protein and valuable bioactive carbohydrate polymers such as chitin. After removal of carotenoid, Black tiger shrimp shell wastes (BTSHWs) were treated with chemicals and protease enzyme to extract chitin. Box–Behnken response surface methodology was applied to optimize the deproteinization process to obtain chitin. At optimal pH (8.82), temperature (50.05 °C), agitation speed (100.98 rpm), enzyme substrate ratio of 1:8 (wv−1) and 72 h of incubation with Paenibacillus woosongensis TKB2 crude protease cocktail, 80 % deproteinization was found along with 77.28 % recovery of chitin. The valuable oligopeptides were determined by MALDI-TOF analysis and analysis of adequate amount of free amino acids in protein hydrolysate from BTSHW, indicating a high nutritional value used for food, feed or as a nitrogen source in growth medium for microorganisms. The chitin obtained was compared with the commercial chitin using scanning electron microscopy, Fourier transform infrared spectrometer, X-ray diffraction and 13C CP/MAS-NMR. Chitin obtained from crude protease treatment showed comparable physicochemical and structural properties to those of the commercial chitin. The carotenoid obtained after treatment can be used for medicinal purpose.Electronic supplementary materialThe online version of this article (doi:10.1007/s13205-014-0245-6) contains supplementary material, which is available to authorized users.

Supplementation with Silk Amino Acids improves physiological parameters defining stamina in elite fin-swimmers.

BackgroundPrevious animal study has shown that supplementation with silk amino acid hydrolysate (SAA) increases stamina in mice. The presented study was the first formal evaluation of the influence of SAA supplementation on parameters defining physiological fitness level in humans.MethodsIt was a randomized controlled trial with a parallel-group design on elite male fin-swimmers. The experimental group was supplemented with 500 mg of SAA per kg of body mass, dissolved in 250 ml of a Carborade Drink®; the control group with Carborade Drink® alone; 3 times a day, 30 minutes prior to the training session.ResultsChanges discerned in the experimental group were more pronounced than those observed in the control group. For example, the change in the serum lactic acid concentration observed in the experimental group was sevenfold less than in the control group [21.8 vs. -3.7 L% for the control and experimental groups, respectively]. An analysis of a lactate profile as a function of a maximal swimming velocity exposed a statistically significant positive shift in the swimming velocity of 0.05 m/s, at the lactate concentration of 4 mmol/L in the experimental group. There was also a positive, although statistically insignificant, increase of 2.6 L% in serum testosterone levels in the experimental group.ConclusionsThis study showed that a 12-day SAA supplementation combined with an extensive and rigorous training schedule was sufficient to increase an aerobic stamina. However, this phenomenon was associated with an augmented level of muscular damage (an increased level of creatine phosphokinase in the experimental group).

Rapid determination of oligopeptides and amino acids in soybean protein hydrolysates using high-resolution mass spectrometry.

Soybean protein hydrolysates (SPHs), especially oligopeptides, have shown a variety of functional properties, including immunomodulatory and anti-oxidant effects. Soybean protein hydrolysate products have been used as functional ingredients in food, sports nutrition or clinical nutrition. However, the mixture is mostly undefined due to its complex nature, containing peptides and minor amino acids as well as small proteins. To develop a specific and efficient method for the identification and structural characterisation of oligopeptides in SPHs, and to determine free amino acids in SPHs in the same analytical run, for evaluation of the chemical profile of SPH products. Accurate mass spectrometry (MS) datasets of SPH samples were recorded on a high-performance liquid chromatography (HPLC) tandem high-resolution (HR) MS system. Potential oligopeptides were tentatively characterised based on their elemental compositions and ring double bond equivalent (RDBE) values, as well as HRMS/MS data. The analytical method to determine amino acids was evaluated in terms of linearity, precision, apparent recovery and limits of detection and quantitation. In total, 186 oligopeptides spanning the mass range of m/z 200-1500 and three major free amino acids could be determined in SPH samples in a single sample injection. Ninety-nine oligopeptides were tentatively characterised. The sensitive and specific instrumental performances also permitted the determination of 19 amino acids with a limit of quantitation of ≤ 0.1 μg/mL. The HPLC-HRMS technique has proven to be an advantageous tool for the rapid characterisation of oligopeptides and determination of amino acids in soybean protein hydrolysates.

LIVING (STAINED) DEEP-SEA FORAMINIFERA OFF HACHINOHE (NE JAPAN, WESTERN PACIFIC): ENVIRONMENTAL INTERPLAY IN OXYGEN-DEPLETED ECOSYSTEMS

Live (Rose-Bengal stained) deep-sea foraminiferal faunas have been studied at five stations between 500–2000-m depth along the NE Japanese margin (western Pacific) to understand how complex environmental conditions (e.g., oxygen depletion, organic matter) control their structure (i.e., diversity, standing stocks, and microhabitats). All stations are characterized by silty sediments with no evidence of recent physical disturbances. The three stations located between 760–1250 m are bathed by dysoxic bottom waters ( 2.2% DW), only the oxygen-depleted sites are characterized by higher concentrations of sugars, lipids, and enzymatically hydrolysable amino acids (EHAA). Sedimentary contents in chlorophyllic pigments decrease with water depth without any major change in their freshness (i.e., [Chl a/(Chl a + Pheo a)] ratios). Both Uvigerina akitaensis and Bolivina spissa are restricted to the stations bathed by dysoxic waters, proving their oxygen-depletion tolerance. In such conditions, both phytophagous taxa are obviously able to take advantage of labile organic compounds (e.g., lipids and EHAA) contained in phytodetritus. Nonionella stella and Rutherfordoides cornuta survive in oxygen-depleted environments probably via alternative metabolic pathways (e.g., denitrification ability) and a large flexibility in trophic requirements. At stations where oxygen availability is higher (i.e., >70 μmol/L in bottom water) and where bioavailable organic compounds are slightly less abundant, diversity indices remain low, and more competitive species (e.g., Uvigerina curticosta, U. cf. U. graciliformis, Nonionella globosa, Nonionellina labradorica, and Elphidium batialis) are dominant.

Stable isotope-labeled collagen: a novel and versatile tool for quantitative collagen analyses using mass spectrometry.

Collagens are the most abundant proteins in animals and are involved in many physiological/pathological events. Although various methods have been used to quantify collagen and its post-translational modifications (PTMs) over the years, it is still difficult to accurately quantify type-specific collagen and minor collagen PTMs. We report a novel quantitative method targeting collagen using stable isotope-labeled collagen named "SI-collagen", which was labeled with isotopically heavy lysine, arginine, and proline in fibroblasts culture. We prepared highly labeled and purified SI-collagen for use as an internal standard in mass spectrometric analysis, particularly for a new approach using amino acid hydrolysis. Our method enabled accurate collagen analyses, including quantification of (1) type-specific collagen (types I and III in this paper), (2) total collagen, and (3) collagen PTMs by LC-MS with high sensitivity. SI-collagen is also applicable to other diverse analyses of collagen and can be a powerful tool for various studies, such as detailed investigation of collagen-related disorders.

Composition of dissolved organic nitrogen in rivers associated with wetlands

As basic information for assessing reactivity and functionality of wetland-associated dissolved organic matter (DOM) based on their composition and structural properties, chemical characteristics of N in ultrafiltered DOM (UDON; >1kD) isolated from wetland-associated rivers in three climates (cool-temperate, Hokkaido, Japan; sub-tropical, Florida, USA; tropical, Sarawak, Malaysia) were investigated. The UDON was isolated during dry and wet seasons, or during spring, summer, and autumn. The proportion of UDON present as humic substances, which was estimated as the DAX-8 adsorbed fraction, ranged from 47 to 91%, with larger values in the Sarawak than at the other sites. The yield of hydrolyzable amino acid N ranged 1.24 to 7.01mgg−1, which correlated positively to the total N content of UDOM and tended to be larger in the order of Florida>Hokkaido>Sarawak samples. X-ray photoelectron N1s spectra of UDON showed a strong negative correlation between the relative abundances of amide/peptide N and primary amine N. The relative abundances of amide/peptide N and primary amine N in the Sarawak samples were smaller (70–76%) and larger (20–23%) respectively compared to those (80–88% and 4–9%) in the Florida and Hokkaido samples. Assuming terminal amino groups and amide N of peptides as major constituents of primary amine N and amide/peptide N, respectively, the average molecular weight of peptides was smaller in the Sarawak samples than that in the Florida and Hokkaido samples. Seasonal variations in UDON composition were scarce in the Sarawak and Florida samples, whereas the distribution of humic substance-N and nonhumic substance-N and compositions of amino acids and N functional groups showed a clear seasonality in the Hokkaido samples. While aromatic N increased from spring to autumn, contributions from fresh proteinaceous materials were also enhanced during autumn, resulting in the highest N content of UDOM for this season.

Influence of nitrogen substrates and substrate C:N ratios on the nitrogen isotopic composition of amino acids from the marine bacterium Vibrio harveyi

Nitrogen (N) isotopic compositions of individual hydrolysable amino acids (δ15NAAs) in N pools have been increasingly used for trophic position assessment and evaluation of sources and transformation processes of organic matter in marine environments. However, there are limited data about variability in δ15NAAs patterns and how this variability influences marine bacteria, an important mediator of trophic transfer and organic matter transformation. We explored whether marine bacterial δ15NAAs profiles change depending on the type and C:N ratio of the substrate. The δ15NAAs profile of a marine bacterium, Vibrio harveyi, was examined using medium containing either glutamate, alanine or ammonium as the N source [substrate C:N ratios (range, 3 to 20) were adjusted with glucose]. The data were interpreted as a reflection of isotope fractionations associated with de novo synthesis of amino acids by bacteria. Principal component analysis (PCA) using the δ15N offset values normalized to glutamate+glutamine δ15N revealed that δ15NAAs profiles differed depending on the N source and C:N ratio of the substrate. High variability in the δ15N offset of alanine and valine largely explained this bacterial δ15NAAs profile variability. PCA was also conducted using bacterial and phytoplankton (cyanobacteria and eukaryotic algae) δ15NAAs profile data reported previously. The results revealed that bacterial δ15NAAs patterns were distinct from those of phytoplankton. Therefore, the δ15NAAs profile is a useful indicator of biochemical responses of bacteria to changes in substrate conditions, serving as a potentially useful method for identifying organic matter sources in marine environments.

Comparative Analysis of Amino Acid Composition in Antarctic Krill and White Shrimp

The purpose of this experiment is to evaluate the nutritional value of amino acids and its commercial value in the fish processing sector in Antarctic krill with cross-referenced in the white shrimp. For determination of the composition of 17 amino acids in the two shrimp muscle, free amino acids were measured using sulfosalicylic acid method, hydrolysed amino acid using hydrochloric acid hydrolysis.17 kinds of hydrolysed amino acids are measured in the muscle of Antarctic krill and White shrimp, which total content is 513.59±18.56mg/g and 537.61±16.8mg/g respectively.16 kinds of free amino acids are measured, which total content is 616.88±44.61mg/100g and 1276±75.67mg/100g respectively, while cysteine is not found. According to amino acid score (AAS), chemical score (CS), the limiting amino acid of Antarctic krill and White shrimp is valine and methionine + cysteine. The umani amino acids accounted for 27.76% of free amino acids and 35.69% of hydrolysed amino acids in Antarctic krill, while White shrimp is 41.08% and 31.52% respectively. The amino acids in Antarctic krill, TAV of which is greater than 1, include glutamic acid, alanine, lysine and arginine.

Dissolved inorganic and organic nitrogen uptake in the coastal North Sea: A seasonal study

Nitrogen incorporation into total particulate suspended matter, hydrolysable amino acids and bacterial biomarker d-Alanine was assessed seasonally in the coastal North Sea using 15N-labeled ammonium, nitrate, nitrite and 15N- and 13C-labeled urea, glycine, leucine, phenylalanine, and two complex pools of dissolved organic matter (DOM) derived from algal and bacterial cultures (A-DOM, B-DOM). We investigated: 1) uptake rates for the various substrates and their contribution to total N uptake; 2) microbial preferences for the different N sources; 3) the coupling of C and N uptake from organic substrates; 4) the contribution of bacteria to the total microbial uptake of these substrates, and 5) the role of a complex pool of organic matter for plankton nutrition. Seasonality in the preferences for N substrates was observed, with A-DOM and B-DOM being preferred in autumn and winter whereas NH4+ was preferentially taken up in spring and summer. C and N uptake was coupled for all the organic substrates, except urea that was mainly used as a nitrogen source in summer and spring. Bacterial contribution to the uptake of A-DOM and B-DOM was, on an annual average, the lowest among the N-substrates. This suggests an important role for phytoplankton in the incorporation of complex organic matter and the importance of DOM for phytoplankton nutrition.

Over-expression of a proline specific aminopeptidase from Aspergillus oryzae JN-412 and its application in collagen degradation.

A strain that exhibited intracellular proline-specific aminopeptidase (PAP) activity was isolated from soy sauce koji and identified as Aspergillus oryzae JN-412. The gene coding PAP was cloned and efficiently expressed in Escherichia coli BL21 in a biologically active form. The highest specific activity reached 52.28 U mg(-1) at optimum cultivation conditions. The recombinant enzyme was purified 3.3-fold to homogeneity with a recovery of 36.7% from cell-free extract using Ni-affinity column chromatography. It appeared as a single protein band on SDS-PAGE with molecular mass of approximately 50 kDa. The purified enzyme exhibited the highest activity at 60 °C and pH 7.5. The enzyme activity was inhibited by PMSF and ions like Zn2+ and Cu2+. DTT, β-mercaptoethanol, EDTA, and ions like Co2+, Mg2+, Mn2+, and Ca2+ had no influence on enzyme activity, whereas Ni2+ enhanced the enzyme activity. By using collagen as a substrate, the purified recombinant prolyl aminopeptidase contributed to the hydrolysis of collagen when used in combination with neutral protease, and free amino acids in collagen hydrolysates was significantly increased.

A novel automethylation reaction in the Aspergillus nidulans LaeA protein generates S‐methylmethionine (555.2)

The filamentous fungi in the genus Aspergillus are opportunistic plant and animal pathogens that produce secondary metabolites including lovastatin, penicillin, and aflatoxin. The synthesis of these small molecules is dependent on gene clusters that are globally regulated by the LaeA protein. Null mutants of LaeA show decreased virulence coupled with reduced secondary metabolism. Although LaeA contains the motifs characteristic of seven‐beta‐strand methyltransferases, a methyl‐accepting substrate of LaeA has not been identified. In this work, we did not find a methyl‐accepting substrate in A. nidulans with various assays including in vivo S‐adenosyl‐[methyl‐3H]methionine labeling, targeted in vitro methylation experiments using putative protein substrates, or in vitro methylation assays using whole cell extracts grown under different conditions. However, in each experiment LaeA was shown to self‐methylate. Amino acid hydrolysis of radioactively‐labeled LaeA followed by cation exchange and reverse phase chromatography identified methionine as the modified residue. Point mutations show that the major site of modification of LaeA is on methionine‐207. LaeA is the first protein to exhibit automethylation at a methionine residue. These findings not only indicate LaeA may perform novel chemistry with S‐adenosylmethionine, but also provide insights into the physiological function of LaeA.Grant Funding Source: Supported by Ruth L. Kirschstein National Research Service Award GM007185

Effects of elevated CO2 on the extractable amino acids of leaf litter and fine roots

Elevated atmospheric CO2 concentrations can change chemistry and input rate of plant tissue to soil, potentially influencing above- and below-ground biogeochemical cycles. Given the important role played by leaf and root litter chemistry in controlling ecosystem function and vulnerability to environmental stresses, we investigated the hydrolyzable amino acid distribution and concentration in leaf and fine root litter among control and elevated CO2 treatments at the Rhinelander free air CO2 enrichment (FACE) experiment (WI, USA). We extracted hydrolyzable amino acids from leaf litter and fine (< 2 mm) roots at three depths for both control and elevated CO2 plots. We found that elevated CO2 decreased the proportion of total leaf amino acid carbon (C), but had no effect on total leaf amino acid nitrogen (N). There was no treatment effect for total root amino acid N or amino acid C for any depth. The decrease in leaf amino acids is probably a result of the shift of protein compounds to more structural compounds. Despite the decrease in leaf amino acid C concentrations, the overall increase in annual plant production under elevated CO2 would result in an increase in plant amino acids to the soil.

A Remodeled Protein Arginine Methyltransferase 1 (PRMT1) Generates Symmetric Dimethylarginine

Protein arginine methylation is emerging as a significant post-translational modification involved in various cell processes and human diseases. As the major arginine methylation enzyme, protein arginine methyltransferase 1 (PRMT1) strictly generates monomethylarginine and asymmetric dimethylarginine (ADMA), but not symmetric dimethylarginine (SDMA). The two types of dimethylarginines can lead to distinct biological outputs, as highlighted in the PRMT-dependent epigenetic control of transcription. However, it remains unclear how PRMT1 product specificity is regulated. We discovered that a single amino acid mutation (Met-48 to Phe) in the PRMT1 active site enables PRMT1 to generate both ADMA and SDMA. Due to the limited amount of SDMA formed, we carried out quantum mechanical calculations to determine the free energies of activation of ADMA and SDMA synthesis. Our results indicate that the higher energy barrier of SDMA formation (ΔΔG(‡) = 3.2 kcal/mol as compared with ADMA) may explain the small amount of SDMA generated by M48F-PRMT1. Our study reveals unique energetic challenges for SDMA-forming methyltransferases and highlights the exquisite control of product formation by active site residues in the PRMTs.

Opportunistic feeding on various organic food sources by the cold-water coral &amp;lt;i&amp;gt;Lophelia pertusa&amp;lt;/i&amp;gt;

Abstract. The ability of the cold-water coral Lophelia pertusa to exploit different food sources was investigated under standardized conditions in a flume. The tested food sources, dissolved organic matter (DOM, added as dissolved free amino acids), bacteria, algae, and zooplankton (Artemia) were deliberately enriched in 13C and 15N. The incorporation of 13C and 15N was traced into bulk tissue, fatty acids, hydrolysable amino acids, and the skeleton (13C only) of L. pertusa. Incorporation rates of carbon (ranging from 0.8–2.4 μg C g−1 DW d–1) and nitrogen (0.2–0.8 μg N g−1 DW d–1) into coral tissue did not differ significantly among food sources indicating an opportunistic feeding strategy. Although total food assimilation was comparable among sources, subsequent food processing was dependent on the type of food source ingested and recovery of assimilated C in tissue compounds ranged from 17% (algae) to 35% (Artemia). De novo synthesis of individual fatty acids by L. pertusa occurred in all treatments as indicated by the 13C enrichment of individual phospholipid-derived fatty acids (PLFAs) in the coral that were absent in the added food sources. This indicates that the coral might be less dependent on its diet as a source of specific fatty acids than expected, with direct consequences for the interpretation of in situ observations on coral nutrition based on lipid profiles.

Antioxidant activity and anti-exercise-fatigue effect of highly denatured soybean meal hydrolysate prepared using neutrase.

Highly denatured soybean meal is a by-product of soybean oil extraction obtained through high-temperature desolventization. High-temperature treatment can result in soybean protein denaturation. Compare with ordinary soybean meal, the protein structure of highly denatured soybean meal has changed. Highly denatured soybean meal was pretreated with thermal treatment or ultrasonication, and then hydrolyzed with neutrase. The ultrasonicated hydrolysate exhibited better antioxidant activity than the thermally treated hydrolysate. The ultrasonication increased 1,1-diphenyl-2-pycryl hydrazyl (DPPH) radical scavenging activity by 8.31% and reduction capacity by 10.19%. The highly denatured soybean meal hydrolysate ultrasonicated at 400W exhibited the highest antioxidant activity. The DPPH radical scavenging activity was 56.22% and reduction capacity was 0.717. The ultrasonicated hydrolysate at 400W was fractionated using ultrafiltration into three fractions: I (>10kDa), II (5kDa to 10kDa), and III (<5kDa). The in vitro antioxidant activity and others in vivo anti-exercise-fatigue effect of the three fractions (I, II, and III) were determined. Fraction III exhibited the highest DPPH radical scavenging activity and reduction capacity, improved the hemoglobin and hepatic glycogen content and reduced blood urea nitrogen and blood lactic acid. Fraction III improved the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) and reduced the malonaldehyde (MDA) content in mouse livers. Therefore, the highly denatured soybean meal hydrolysate has an anti-oxidative effect and it significantly alleviates exercise-fatigue in mice. Amino acids of hydrolysate were determined. Results showed that the antioxidant activity and anti-exercise-fatigue effect were related to the amino acid compositions.

Sources, distributions, and early diagenesis of sedimentary organic matter in the Pearl River region of the South China Sea

Suspended particles from the Pearl River, and surface sediments from the northern South China Sea (NSCS) were analyzed for elemental composition (C, N), stable carbon isotopic composition (δ13C), lignin phenols, and total hydrolyzable amino acids (THAA). Organic matter (OM) in riverine particles was depleted in 13C (avg. −28.3‰) and was derived primarily from plankton and soils, with minor contributions from C3 plant material. The δ13C of sedimentary OM became increasingly enriched in 13C (avg. −21.3‰) from the inner shelf to the slope of the NSCS, and C/N ratios decreased from the inner shelf to the slope, indicating increasing contributions of marine organic carbon (OC). Lignin phenol yields in sedimentary OM decreased from the inner shelf to the slope, indicating declining contributions of terrestrial OC. Lignin phenol compositions in riverine particles and marine sediments reflected a predominately angiosperm source. Degradation indices (DI) of sedimentary amino acids indicated increasing diagenetic alteration of marine OM with water depth and distance offshore. Increasing acid:aldehyde ratios (Ad/Al) in lignin phenols and 3,5-dihydroxybenzoic acid:vanillyl phenols (3,5-BD/V) ratios also indicated a seaward increase in the diagenetic state of terrestrial OM, presumably due to hydrodynamic sorting and biogeochemical processing. A three end-member mixing model based on lignin phenol yields and stable C isotopic compositions was used to distinguish sources of OM. Marine OM accounted for an increasing fraction (62–82%) of sedimentary OC from the inner shelf to the slope, whereas soil-derived OM accounted for a decreasing fraction (39–18%) of sedimentary OC from inner shelf to the slope. The contribution of C3 plant OM was negligible. The significant contributions of terrestrial OM in NSCS sediments are ascribed to the relatively refractory nature of soil OM and the bioavailable nature of marine OM.

Concentrations and distributions of amino acids in black and white smoker fluids at temperatures over 200 °C

The distribution of amino acids in seafloor hydrothermal systems was investigated through the determination of the concentrations of total hydrolysable amino acids (THAAs), dissolved free amino acids (DFAAs) and cell density in>200°C black and white smoker fluids sampled from the Mariana Trough. THAA concentrations of>10μM were detected in the black and white smoker fluids, which are higher than those of low temperature (< 53°C) fluids and ambient seawater (< 1μM). 1.4×104–8.6×105cell/ml of microbe was detected from low temperature hydrothermal fluids (< 100°C) and ambient seawater. The concentration of THAAs increased with increasing temperature, although the cell density decreased in high temperature fluid (> 150°C). The bioactivity would be restricted under the high temperature condition.Levels of DFAAs (< 0.7μM) were very low, suggesting that the amino acids existed mainly as polymers in these hydrothermal fluids. The amino acid polymers plausibly derive from biological protein and dissolve during the reaction of hydrothermal fluids along flow paths around the hydrothermal vents.Amino acids are considered to be unstable under hydrothermal condition (> 200°C). However, labile amino acids (e.g., Asp and Ser) were abundant in high temperature fluids. These amino acids would be protected by reaction with inorganic compounds. The behavior of the amino acids derived from organisms around hydrothermal vents would be constrained more by abiotic physico-chemical reactions than biological activities in hydrothermal systems.