kDa Peptide Research Articles

Expression of HSP70 family mRNAs in albino northern snakehead, Channa argus: Response to extreme temperature stress and bacterial infection

The wild albino northern snakehead, Channa argus, has only been found in Jialing Rivers System of China so far. It is easy to be affected by the environmental factors such as temperature changes and bacterial infection, thus causing a huge economic loss. Therefore, this study cloned a 2,213 bp cDNA that encodes a protein of heat shock protein 70 (CaHSP70), which has an open reading frame (ORF) that encodes 639 amino acids and the corresponding polypeptides of 70.50 kDa. And the oretical isoelectric point (pI) of CaHSP70 is 5.79. Additionally, we also cloned a cDNA for heat shock cognate protein 70 (CaHSC70) with a total length of 2,300 bp. And the ORF of CaHSC70 encodes 648 amino acids and 71.18 kDa peptides. The pI of CaHSC70 is 5.22. Moreover, the cDNA length of stress-70 protein mitochondrial (CaHSPA9) is 2,944 bp with an ORF that encodes 679 amino acids, polypeptides of 73.74 kDa, and a pI of 6.68. The quantitative real-time PCR (qRT-PCR) analysis showed that the mRNA expression levels of CaHSP70, CaHSC70, and CaHSPA9 genes were tissue-specific in the control groups. After the heat shock at 37 °C, the mRNA expression levels of CaHSP70 were extremely significantly upregulated in the kidney, liver, spleen, and brain tissues, while fewer mRNA expression levels of CaHSC70 and CaHSPA9 showed a relatively induction in these tissues. In contrast, after the cold shock at 8.5 °C, fewer mRNA expression levels of CaHSP70, CaHSC70, and CaHSPA9 showed the changes of expression in all the tissues, compared to heat shock. In addition, CaHSP70, CaHSC70, and CaHSPA9 mRNA expression levels showed an overall trend of first upregulating and then falling after Edwardsiella tarda (strain No. DL1,476) challenge. In conclusion, this study demonstrated that temperature had a great effect on the mRNA expression levels of CaHSP70, CaHSC70, and CaHSPA9, and the mRNA expression levels of these three genes were also sensitive to pathogen infection, especially CaHSP70 in the albino C. argus.

The immune-enhancing potential of peptide fractions from fermented Spirulina platensis by mixed probiotics.

Mixed fermentation with different microorganisms can facilitate fermentation metabolism and increase the low molecular metabolites accumulation, thereby enhancing the bioactive activity. In this study, we evaluated the immune-stimulating activities of Spirulina platensis and different extracts from fermented S. platensis (FS) by mixed probiotics in vitro, by measuring the proliferation and Th1/Th2 immunomodulatory potential on murine primary splenic lymphocytes. The results showed that mixed fermentation enhanced the immunomodulatory activity of S. platensis with higher lymphocyte proliferation compared with non-fermented S. platensis (NFS). Notably, the low molecular weight (<3kDa) peptide fraction from fermented S. platensis (L-PFS), especially at 40μg/ml, presented the strongest activity in promoting lymphocytes proliferation and modulating cytokines (IL-2 and IL-10) secretion. Meanwhile, L-PFS enhanced the relative mRNA expression of Th1 cytokine (IFN-γ) and Th2 cytokine (IL-4), along with inhibiting the relative mRNA expression of Th1 cytokines (IL-2 and TNF-α) and Th2 cytokine (IL-10) compared with Concanavalin A-treated lymphocytes. PRACTICAL APPLICATIONS: Fermentation with mixed probiotics could effectively improve the bioactive activity of S. platensis. In particular, L-PFS screened from the FS could significantly contribute to the immune-enhancing activity of lymphocytes, promote the Th1/Th2 balance, and provide insights for the investigation of FS as the potential immunomodulatory food products.

Effects of single-dose protons or oxygen ions on function and structure of the cardiovascular system in male Long Evans rats

PurposeStudies are required to determine whether exposures to radiation encountered during manned missions in deep space may have adverse effects on the cardiovascular system. Most of the prior studies on effects of simulated space radiation on the heart and vasculature have been performed in mouse models. To provide data from a second animal species, two studies were performed to assess effects of high-energy charged particle radiation on the heart and abdominal aorta in a rat model. Materials and methodsIn study A, male Long Evans rats were exposed to whole-body protons (250 MeV, 0.5 Gy) or oxygen ions (16O, 600 MeV/n, 0.5 Gy), and ultrasonography was used to measure in vivo cardiac function and blood flow parameters at 3, 5, 9 and 12 months after radiation, followed by tissue collection at 12 months. In study B, male Long Evans rats were exposed to 16O (1 GeV/n, 0.01-0.25 Gy), and hearts collected at 6 to 7 and 12 months for histology and western-blots. ResultsBoth protons (250 MeV) and 16O (600 MeV/n) caused a decrease in left ventricular posterior wall thickness at 3-5 months, but did not change echocardiographic measures of cardiac function. In Pulsed-wave Doppler assessment of the abdominal aorta, an increase was seen in mean velocity, peak velocity, and velocity time integral at 12 months after 16O (600 MeV/n), suggesting a change in vascular function. There were no significant changes in histopathology or histological quantification of total collagens in heart or aorta. On the other hand, an increase was seen in a 75 kDa peptide of collagen type III in the left ventricle of rats exposed to protons (250 MeV) and 16O (600 MeV/n and 1 GeV/n), suggesting that radiation caused remodeling of existing collagens in the heart. 16O (600 MeV/n and 1 GeV/n) caused increases in left ventricular protein levels of immune cell markers CD2, CD4, CD8, and CD68. ConclusionA single low dose of whole body protons or 16O in male Long Evans rats did not change cardiac function or induce gross pathological changes in the heart or aorta, but induced mild changes in vascular function and remodeling of existing collagens in the heart. Altogether, studies in prior mouse models and the current work in rats indicate minor changes in cardiac function and structure after a low dose of single-ion radiation.

Exogenous 10 kDa-Heat Shock Protein Preserves Mitochondrial Function After Hypoxia/Reoxygenation.

Humoral factors released during ischemic preconditioning (IPC) protect the myocardium against ischemia/reperfusion (I/R) injury. We have recently identified 10 kDa-heat shock protein (HSP10) and a fraction of small 5–10 kDa peptides (5–10-sP) in the coronary effluent of IPC-treated hearts and demonstrated their cardioprotective potential. We here used our isolated mitochondria model to characterize the impact of exogenous HSP10 and 5–10-sP on mitochondria function from myocardium subjected to I/R injury. Isolated perfused rat hearts were submitted to 30-min global ischemia and 10-min reperfusion. Before ischemia, isolated hearts were infused with saline or 5–10-sP, with or without a mitochondrial ATP-sensitive-K+-channel blocker (5HD 10 μmol·L−1) or PKC inhibitor (chelerythrine 10 μmol·L−1), before I/R. HSP10 (1 µmol·L−1) was infused into isolated hearts before I/R without blockers. At 10-min reperfusion, the mitochondria were isolated and mitochondrial function was assessed. In a subset of experiments, freshly isolated mitochondria were directly incubated with HSP10 or 5–10-sP with or without 5HD or chelerythrine before in vitro hypoxia/reoxygenation. Infusion of 5–10-sP (n = 5) and HSP10 (n = 5) into isolated hearts before I/R improved mitochondrial ADP-stimulated respiration, ATP production and prevented mitochondrial ROS formation compared to the I/R group (n = 5); this effect was abrogated by 5HD and chelerythrine. In freshly isolated mitochondria with in vitro hypoxia/reoxygenation, HSP10 (n = 16) and 5–10-sP (n = 16) incubation prevented reductions of mitochondrial ADP-stimulated respiration (91.5 ± 5.1 nmol O2/min/mg PTN), ATP production (250.1 ± 9.3 μmol ATP/200μg PTN), and prevented mitochondrial ROS production (219.7 ± 9.0 nmol H2O2/200μg PTN) induced by hypoxia/reoxygenation (n = 12, 51.5 ± 5.0 nmol O2/min/mg PTN; 187 ± 21.7 μmol ATP/200 μg PTN; 339.0 ± 14.3 nmol H2O2/200 μg PTN, p < 0.001, respectively). 5HD reduced the ADP-stimulated respiration in the HSP10 group (65.84 ± 3.3 nmol O2/min/mg PTN), ATP production (193.7 ± 12.1 μmol ATP/200μg PTN) and increased ROS in the 5–10-sP group (274.4 ± 21.7 nmol H2O2/200 μg PTN). Mitochondria are a target of the cardioprotection induced by 5–10-sP and HSP10. This protection is dependent of PKC and mKATP activation. HSP10 can act directly on mitochondria and protects against hypoxia/reoxygenation injury by mKATP activation.

Anti-stress phytohormones impact on proteome profile of green gram (Vigna radiata) under salt toxicity

Anti-stress phytohormones impact on proteome profile of green gram (Vigna radiata) under salt toxicity

Enzymatically derived sunflower protein hydrolysate and peptides inhibit NFκB and promote monocyte differentiation to a dendritic cell phenotype

Enzymatic hydrolysis of proteins produces bioactive peptides that have the potential to provide health benefits. This study examined the inflammatory- and immune-modulating properties of a flavourzyme-derived sunflower protein hydrolysate (SPH) and peptides. The SPH was fractionated into <1, 1–3, 3–5, and >5 kDa peptides by membrane ultrafiltration. The SPH blunted IL-1β stimulated NFκB activation and boosted IL-4/GM-CSF induced expression of surface markers CD14 and CD86, indicating maturation into a dendritic cell (DC) phenotype. Testing of SPH membrane ultrafiltration and HPLC fractions indicated that smaller and non-polar peptides were the most potent, respectively. Four novel peptides (YFVP, SGRDP, MVWGP and TGSYTEGWS) were identified and all of them blunted IL-1β stimulated NFκB activation. The peptides also boosted IL-4/GM-CSF induction of CD14, while only MVWGP and TGSYTEGWS boosted the expression of CD86. MVWGP was the most potent immune-modulatory peptide across all cellular assays, which was attributed to the presence of a methionine residue.

Structural and Gene Characterization of a New Antifungal Peptide Obtained from Penicillium crustosum FP11 Strain

A novel antifungal peptide, PcAFP (6.48 kDa, pI 8.83), was obtained from the culture supernatant of the fungus Penicillium crustosum. The gene encoding the PcAFP peptide was isolated based on its homologue in Penicillium chrysogenum, PgAFP. PcAFP is a small, cystine-rich peptide, and the mature peptide consists of 58 amino acid residues. The immature P. crustosum antifungal protein (AFP) showed 95.65% identity to the antifungal protein of P. chrysogenum, while the mature peptide showed 98.28% identity with PgAFP. Molecular modeling of the tertiary structure of the mature peptide revealed details of the conserved structure of the AFPs, such as the β-barrel motif stabilized by three disulfide bonds and the l-core motif. Analysis of the extract by 16% tricine SDS-PAGE showed a 6.9 kDa peptide, which was close to the predicted molecular mass of the mature peptide of 6.48 kDa. Assays of antimicrobial activity, performed by broth microdilution using the crude extract obtained from the culture medium, showed activity against Candida albicans. These results demonstrate the conservation of the PcAPF gene and the high level of identity with the PgAFP antifungal protein of P. chrysogenum. Given these structural and biochemical characteristics, PcAFP could be a potential candidate for future investigations that may aid in the development of new antifungal compounds.

Enhancing Activities of Salt-Tolerant Proteases Secreted by Aspergillus oryzae Using Atmospheric and Room-Temperature Plasma Mutagenesis.

Aspergillus oryzae 3.042 was mutagenized using atmospheric and room-temperature plasma (ARTP) technology to enhance its salt-tolerant proteases activity. Compared to the starting strain, mutant H8 subjected to 180 s of ARTP treatment exhibited excellent genetic stability (15 generations), growth rate, and significantly increased activities of neutral proteases, alkaline proteases, and aspartyl aminopeptidase during fermentation. Mutant H8 significantly enhanced the contents of 1-5 kDa peptides, aspartic acid, serine, threonine, and cysteine in soy sauce by 16.61, 7.69, 17.30, 8.61, and 45.00%, respectively, but it had no effects on the contents of the other 14 free amino acids (FAAs) due to its slightly enhanced acidic proteases activity. Analyses of transcriptional expressions of salt-tolerant alkaline protease gene (AP, gi: 217809) and aspartyl aminopeptidase gene (AAP, gi: 6165646) indicated that their expression levels were increased by approximately 30 and 27%, respectively. But no mutation was found in the sequences of AP and AAP expression cassettes, suggesting that the increased activities of proteases in mutant H8 should be partially attributed to the increased expression of proteases. ARTP technology showed great potential in enhancing the activities of salt-tolerant proteases from A. oryzae.

NC1-peptide regulates spermatogenesis through changes in cytoskeletal organization mediated by EB1.

During the epithelial cycle of spermatogenesis, different sets of cellular events take place across the seminiferous epithelium in the testis. For instance, remodeling of the blood-testis barrier (BTB) that facilitates the transport of preleptotene spermatocytes across the immunological barrier and the release of sperms at spermiation take place at the opposite ends of the epithelium simultaneously at stage VIII of the epithelial cycle. These cellular events are tightly coordinated via locally produced regulatory biomolecules. Studies have shown that collagen α3 (IV) chains, a major constituent component of the basement membrane, release the non-collagenous (NC) 1 domain, a 28-kDa peptide, designated NC1-peptide, from the C-terminal region, via the action of MMP-9 (matrix metalloproteinase 9). NC1-peptide was found to be capable of inducing BTB remodeling and spermatid release across the epithelium. As such, the NC1-peptide is an endogenously produced biologically active peptide which coordinates these cellular events across the epithelium in stage VIII tubules. Herein, we used an animal model, wherein NC1-peptide cloned into the pCI-neo mammalian expression vector was overexpressed in the testis, to better understanding the molecular mechanism by which NC1-peptide regulated spermatogenic function. It was shown that NC1-peptide induced considerable downregulation on a number of cell polarity and planar cell polarity (PCP) proteins, and studies have shown these polarity and PCP proteins modulate spermatid polarity and adhesion via their effects on microtubule (MT) and F-actin cytoskeletal organization across the epithelium. More important, NC1-peptide exerted its effects by downregulating the expression of microtubule (MT) plus-end tracking protein (+TIP) called EB1 (end-binding protein 1). We cloned the full-length EB1 cDNA for its overexpression in the testis, which was found to block the NC1-peptide-mediated disruptive effects on cytoskeletal organization in Sertoli cell epithelium and pertinent Sertoli cell functions. These findings thus illustrate that NC1-peptide is working in concert with EB1 to support spermatogenesis.

Matrix Metalloproteases and Cathepsin D in Human Serum do not Cleave Prolactin to Generate Vasoinhibin.

Vasoinhibin is generated in the pituitary gland and in multiple target tissues by proteolytic cleavage of prolactin by matrix metalloproteinases and cathepsin D. A dysregulation of vasoinhibin generation appears to contribute to diabetic retinopathy and diabetic macular edema, retinopathy of prematurity, peripartum cardiomyopathy, and preeclampsia. Here, we investigate whether vasoinhibin is generated by matrix metalloproteinases and cathepsin D in human serum. The abundance of matrix metalloproteinases 1, 2, 3, 8, 9, 10, 13, tissue inhibitors of metalloproteinases 1, 2, 4, and the activity of cathepsin D in serum samples were determined. Samples from healthy male (n = 3) and female (n = 2) subjects, pregnant subjects (n = 2), and patients with type 2 diabetes mellitus (n = 2) were investigated. The samples were incubated with recombinant prolactin at 37°C, under different pH, time, and buffer conditions. Prolactin and cleaved prolactin products were investigated by SDS-PAGE and western blotting. Matrix metalloproteases-1, -2, -3, -8, -9, -10, -13, TIMP-1, -2, and -4, and the activity of cathepsin D were detected in all sera. Full-length prolactin incubated with human sera, containing endogenous matrix metalloproteinases and cathepsin D, remained intact at neutral pH during a time frame from 1 to 24 hours. Partial enzymatic cleavage of prolactin resulting in the generation of a vasoinhibin-like 17 kDa peptide was observed in samples incubated at pH 3.4. Heat inactivation of the serum and the addition of an MMP inhibitor suppressed the generation of the 17 kDa peptide, indicating that its generation was MMP-mediated. Vasoinhibin generation by enzymatic cleavage of prolactin by matrix metalloproteases or cathepsin D does not occur in human serum at physiological pH. A limited proteolysis of prolactin, resulting in the generation of a vasoinhibin-like peptide with an apparent molecular weight of 17 kDa occurs in serum at acidic pH. The generation of vasoinhibin may require the cellular and tissue microenvironments.

Human Enteric Defensin 5 Promotes Shigella Infection of Macrophages.

Human α-defensins are 3- to 5-kDa disulfide-bridged peptides with a multitude of antimicrobial activities and immunomodulatory functions. Recent studies show that human enteric α-defensin 5 (HD5), a host defense peptide important for intestinal homeostasis and innate immunity, aids the highly infectious enteropathogen Shigella in breaching the intestinal epithelium in vitro and in vivo Whether and how HD5 influences Shigella infection of resident macrophages following its invasion of the intestinal epithelium remain poorly understood. Here, we report that HD5 greatly promoted phagocytosis of Shigella by macrophages by targeting the bacteria to enhance bacterium-to-cell contacts in a structure- and sequence-dependent fashion. Subsequent intracellular multiplication of phagocytosed Shigella led to massive necrotic cell death and release of the bacteria. HD5-promoted phagocytosis of Shigella was independent of the status of the type 3 secretion system. Furthermore, HD5 neither inhibited nor enhanced phagosomal escape of Shigella Collectively, these findings confirm a potential pathogenic role of HD5 in Shigella infection of not only epithelial cells but also macrophages, illuminating how an enteropathogen exploits a host protective factor for virulence and infection.

Evaluation of biochemical and antioxidant dynamics during the co-fermentation of dehusked barley with Rhizopus oryzae and Lactobacillus plantarum.

Barley is an ancient and important functional crop. In this study, the biochemical and antioxidant dynamics of dehusked barley during co-fermentation with Lactobacillus plantarum and Rhizopus oryzae were investigated. Results showed that amino acid nitrogen, soluble protein, <10kDa peptide, and free phenolic contents increased with fermentation time; whereas the lacticacid bacteria count, reducing sugar, and free flavonoid contents showed a tendency to increase first and then decrease. SDS-PAGE analysis indicated that bands at>25 and<18.4kDa were shown with improved intensity with time, whereas bands at 18.4-25kDa were disappeared. Additionally, fermentation time led to an increase in DPPH, hydroxyl, ABTS+ radical scavenging activity, and ferric reducing antioxidant power. Thus, this study demonstrated that co-fermentation with L. plantarum and R. oryzae could improve nutrition and potential bioactivity of barley, and use barley as a good solid-state food carrier for probiotics. PRACTICAL APPLICATIONS: Barley is rich in nutrition and has a huge production. However, due to its high-fiber and special protein composition, there is a certain palatability problem whether it is used to produce flour or other products. Therefore, most of the barley is destined to animal feed and malt, and only a small part is used directly for human consumption. Aiming at this problem, on the basis of the optimization of the fermentation process at early stage, our results further demonstrated co-fermentation with L. plantarum and R. oryzae could enhance the nutritional value and potential bioactivity of barley, thus providing a novel approach to develop functional barley food and improve the direct utilization rate of barley in food processing.

Production and characterisation of antioxidant peptides from sweet potato protein by enzymatic hydrolysis with radio frequency pretreatment

SummaryEffect of radio frequency (RF at 70, 80 and 90 °C) pretreatment on production and characterisation of sweet potato protein hydrolysates (SPPH) prepared using Alcalase (ALC), Protease (PRO) and the combination of ALC + PRO was investigated. RF highly improved degree of hydrolysis (DH) and enhanced antioxidant activity of all SPPH produced by ALC, PRO and the combination as compared to traditional water bath (WB) heating pretreatment (P &lt; 0.05). RF significantly increased molecular weight (MW) &lt;3 kDa peptide fraction from SPPH produced by ALC, and MW &lt;3 kDa peptide fraction from RF80‐ and RF90‐pretreated samples has higher antioxidant activity. Diverse peptides in MW &lt;3 kDa fractions with RF80 and RF90 pretreatments were identified using LC–QTOF–MS/MS, which matched the sequences of sporamins and contained antioxidant amino acids Trp, Tyr, Met, Phe and/or His. There is a great potential application of using SPPH in functional foods as a novel ingredient.

A Curcumin Analog Reduces Levels of the Alzheimer's Disease-Associated Amyloid-β Protein by Modulating AβPP Processing and Autophagy.

Alzheimer's disease (AD) is a devastating neurodegenerative disease with no cure currently available. A pathological hallmark of AD is accumulation and deposition of amyloid-β protein (Aβ), a ∼4 kDa peptide generated through serial cleavage of the amyloid-β protein precursor (AβPP) by β- and γ-secretases. Curcumin is a natural compound primarily found in the widely used culinary spice, turmeric, which displays therapeutic potential for AD. Recently, we reported the development of curcumin analogs and identified a lead compound, curcumin-like compound-R17 (CLC-R17), that significantly attenuates Aβ deposition in an AD transgenic mouse model. Here, we elucidated the mechanisms of this analog on Aβ levels and AβPP processing using cell models of AD. Using biochemical methods and our recently developed nanoplasmonic fiber tip probe technology, we showed that the lead compound potently lowers Aβ levels in conditioned media and reduces oligomeric amyloid levels in the cells. Furthermore, like curcumin, the lead compound attenuates the maturation of AβPP in the secretory pathway. Interestingly, it upregulated α-secretase processing of AβPP and inhibited β-secretase processing of AβPP by decreasing BACE1 protein levels. Collectively, our data reveal mechanisms of a promising curcumin analog in reducing Aβ levels, which strongly support its development as a potential therapeutic for AD.

Antihypertensive and antioxidant activities of enzymatic wheat bran protein hydrolysates.

Bioactive peptides from plant protein sources have been continuously identified as nutrient supplements for low toxicity but multiple physiological activities such as antihypertensive, antioxidant, and anti-inflammatory. In this study, wheat bran protein isolate was digested with alcalase to produce wheat bran protein hydrolysate (WPH) that was then separated into different peptide fractions (<1, 1-3, 3-5, and 5-10kDa) by membrane ultrafiltration. WPH and the peptide fractions were evaluated for in vitro activities such as antioxidant, renin inhibition, and angiotensin-converting enzyme (ACE) inhibition. In addition, the blood pressure-lowering effects of WPH and the<1kDa peptides were determined by oral administration to spontaneously hypertensive rats (SHRs). Results showed that the ACE and renin inhibitions were significantly (p<.05) higher for the<1kDa fraction (84.25%±2.45%, 75.19%±1.75%, respectively) when compared to the WPH and>1kDa fractions. The<1kDa fraction also showed significantly (p<.05) higher oxygen radical antioxidant activity with 2044.73±37.45 (μM TE/g protein) when compared to lower values obtained for the>1kDa membrane fractions and WPH. Oral administration (100mg/kg body weight) of the<1kDa membrane fraction to SHRs resulted in a better decrease (-35mmHg) in the systolic blood pressure when compared to the WPH (-20mmHg) after 6hr. And seven peptides (NL, QL, FL, HAL, AAVL, AKTVF, and TPLTR) were identified and amino acid sequence was determined by tandem mass spectrometry. We conclude that the WPH could be considered as a suitable natural antihypertensive and antioxidant resource. PRACTICAL APPLICATIONS: The results of the present study indicate that WPH and its ultrafiltration fractions possess potential as a source of antihypertensive and strong antioxidant peptides. It has been proved that wheat bran has a good blood pressure lowering and antioxidation and other biological activities, and the<1kDa fraction showing high oxygen radical absorbance capacity level also has better in vitro ACE inhibition and renin-inhibitory activity. The higher antihypertensive efficiency of the<1kDa fraction may be because the peptides can be better absorbed from the gastrointestinal tract or an increased ability to interact with the enzyme (ACE or renin) protein structure to change the active conformation and lead to decreased catalysis. The results of this study indicate that WPH, especially<1kDa peptide, can be used as a component in formulating antihypertensive functional foods and nutraceuticals, thus improving the industrial production efficiency and bioavailability of wheat bran.

Urinary Amino-Terminal Pro–C-Type Natriuretic Peptide: A Novel Marker of Chronic Kidney Disease in Diabetes

Chronic renal inflammation and fibrosis are common sequelae in diabetes mellitus (DM) and are major causes of premature mortality. Although upregulation of NPPC expression occurs in response to renal inflammation in experimental animals, nothing is known of the molecular forms of C-type natriuretic peptide (CNP) products in urine of people with DM or links with renal function. ProCNP products in urine were characterized with HPLC and a range of antisera directed to specific epitopes of amino-terminal proCNP (NTproCNP). The 5-kDa intact peptide was quantified in spot urine samples from healthy adults and 202 participants with DM selected to provide a broad range of renal function. The predominant products of proCNP in urine were consistent with the 2-kDa fragment (proCNP 3-20) and a smaller peak of intact (5-kDa) fragment (proCNP 1-50, NTproCNP). No peaks consistent with bioactive forms (proCNP 82-103, 50-103) were identified. The urine NTproCNP to creatinine ratio (NCR) was more reproducible than the albumin to creatinine ratio (ACR) and strongly associated with the presence of chronic kidney disease. In models predicting independence, among 10 variables associated with renal function in DM, including plasma NTproCNP, only 3 (sex, ACR, and plasma creatinine) contributed to NCR. Characterization of the products of proCNP in urine confirmed the presence of NTproCNP. In spot random urine from study participants with DM, NCR is inversely associated with estimated glomerular filtration rate. In contrast to ACR, NCR reflects nonvascular factors that likely include renal inflammation and fibrosis.

The composition and health benefits of mackerel concentrate

The objective of this study was to study the protein profile and amino acid composition of the mackerel concentrates from fish meat protein processed by enzymatic hydrolysis and then treated by high pressure-low temperature concentration. Mackerel peptide was prepared and health benefits were analyzed by human subject research. The results showed that the mackerel concentrates had significantly higher MW&lt;10kDa peptide than the cooking juice remained. The concentrate contained abundant branched chain amino acids and taurine that related to anti-fatigue activity. Quality-of-Life (QOL) improvement and antihypertensive effect of mackerel concentrate were also proven. This study suggested that mackerel hydrolyzate may potentially serve as a good source of healthy oligopeptide and could be transformed into novel value-added functional food supplement.

Isolation and Characterization of Angiotensin Converting Enzyme Inhibitory Peptides from Peach Seed Hydrolysates: In Vivo Assessment of Antihypertensive Activity.

A peptide fraction with molecular masses below 3 kDa (PSH-3 kDa) from a peach seed hydrolysate demonstrated high angiotensin converting enzyme (ACE) inhibitory activity (concentration to inhibit 50% ACE (IC50) = 16.4 μg/mL) in our previous work. This work proposes a further study of this highly active fraction. RP-HPLC enabled two fractions (F3 and F4) with high inhibitory activity (IC50 = 2.0 ± 0.5 and 1.2 ± 0.2 μg/mL, respectively) to be isolated. Peptide analysis by LC-Q-TOF-MS/MS using reverse-phase and hydrophilic interaction chromatography enabled 33 peptides within both fractions to be identified. Among them, peptide isoleucine-tyrosine-serine-proline-histidine (IYSPH) showed the highest capacity. The lack of cytotoxicity of peptides was demonstrated in three different cell lines (HeLa, HT-29, and HK-2). Oral administration of PSH-3 kDa fraction or peptide IYSPH caused a significant systolic blood pressure reduction (-30 mmHg) on spontaneously hypertensive rats after 3-6 h treatment.

Effects of sonication during moromi fermentation on antioxidant activities of compounds in raw soy sauce

To elucidate the effects of sonication on the antioxidant activities of compounds in soy sauce, sonication at 68 kHz (60 W/L/10 min/8 circles) was employed during moromi fermentation. Sonication enhanced four antioxidant indices of soy sauce from 5.29% to 24.29%, which were attributed to the significantly higher levels of free amino acids (FAAs, 12.45%), total phenolics (26.71%) and 1–3 kDa peptides (12.28%) in sonicated moromi. Amongst them, FAAs contributed 65.88% and 53.45% to the enhanced metal ion chelating activity and DPPH radical scavenging activity (p < 0.05), respectively. However, Maillard reaction products and isoflavones contributed little to the enhanced antioxidant activities, because sonication slightly affected Maillard reaction products, isoflavones and β-glucosidase activities during moromi fermentation. It was concluded that cell wall of soybean was destroyed by sonication, facilitating the release of antioxidant compounds, which significantly enhanced the antioxidant activities in raw soy sauce.

Preparation and identification of angiotensin I‐converting enzyme inhibitory peptides from sweet potato protein by enzymatic hydrolysis under high hydrostatic pressure

SummarySweet potato protein hydrolysates (SPPH) with angiotensin I‐converting enzyme (ACE) inhibitory activity were prepared by papain, pepsin and alcalase under high hydrostatic pressure (HHP, 100–300 MPa). HHP significantly increased degree of hydrolysis (DH), nitrogen recovery (NR) and molecular weight (MW) &lt;3 kDa fractions contents of SPPH by all three enzymes (P &lt; 0.05). MW &lt; 3 kDa peptide fractions from SPPH by alcalase under 100 MPa showed the highest ACE inhibitory activity (IC50 value 32.24 µg mL−1), and was subjected to purification and identification by semi‐preparative RP‐HPLC and LC‐MS/MS. Fifty‐four peptides ranged from 501.28 to 1958.88 Da with 5–18 amino acids were identified and matched sporamin A and B sequences. Five identified peptides with sequences of VSAIW, AIWGA, FVIKP, VVMPSTF and FHDPMLR displayed good ACE inhibitory activity with the contribution of Val, Trp, Phe and Arg. Thus, SPPH by enzymatic hydrolysis under HHP can be potentially used in functional food.