SEARCH · PubMed Health

Results for “Bioactive peptide”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources

PubMed1991

Purification and characterization of leucine-specific aminopeptidase from the soluble fraction of human placenta.

A soluble aminopeptidase distinct from two enzymes described previously was isolated from human placenta and some of its properties were investigated. The three aminopeptidases were separated by DEAE-cellulose chromatography. The newly found aminopeptidase exhibits specific hydrolysis of leucine derivatives among various synthetic substrates. However, a broad substrate specificity was observed toward some natural bioactive peptides.

Amino Acid Sequence↗

PubMed1991

Cell-surface enzymes and lymphocyte functions.

Recent studies have provided insights into the enzymatic functions of many surface molecules expressed by monocytes and lymphocytes. These ectoenzymes act as cell-differentiation markers of lymphomonocytic lineages; some of them are also involved in activation, signal-transduction and cell-matrix adhesion processes, as well as in the regulation of biological responses of bioactive peptides.

Animals↗

PubMed1996

Hepatocyte growth factor and its actions in growth plate chondrocytes.

Hepatocyte growth factor (HGF) has been implicated as a paracrine regulator of organogenesis and repair in many tissues. Here we have studied the expression and actions of HGF in intact rachitic rat growth plate and derived cultures of proliferative zone chondrocytes. In vivo and in vitro chondrocytes express HGF mRNA; 1,25(OH)2 has a three-fold maximal stimulatory effect, which can be blocked by H-7, an inhibitor of protein kinase C. Although HGF elaboration and action generally follow a paracrine model, chondrocytes appear capable of both expressing and responding to HGF. mRNA encoding the HGF receptor (c-met) was detected in both growth cartilage and derived chondrocyte cultures. HGF addition to chondrocyte cultures increased collagen II mRNA and alkaline phosphatase enzymatic activity to degrees comparable to that observed for active vitamin D metabolites. Combining HGF and 1,25-D evoked a synergistic response (ninefold) of alkaline phosphatase activity. To assess whether a similar stimulatory effect might be seen with bioactive peptides and HGF, we investigated the effect of HGF pretreatment on acute responses of chondrocytes to synthetic human calcitonin, an anabolic chondrocyte regulator whose skeletal action are mediated principally by cAMP elevation and subsequent protein kinase A activation. CT's maximal activation of protein kinase A was increased by prior HGF treatment from 56% to 78%. In concert, our findings indicate that in addition to HGF's classical paracrine role during skeletal growth, this growth factor may modulate hormonal sensitivity of the chondrocyte during proliferation, differentiation, and/or apoptosis.

Alkaline Phosphatase↗

PubMed2005

Lactobacillus helveticus fermented milk lowers blood pressure in hypertensive subjects in 24-h ambulatory blood pressure measurement.

BACKGROUND: The present study was carried out to evaluate the blood pressure (BP)-lowering effect and the safety aspects of Lactobacillus helveticus LBK-16H fermented milk with high tripeptide doses on hypertensive subjects using 24-h ambulatory measurements (ABPM). METHODS: In a randomized, double blinded placebo-controlled parallel group study, 94 hypertensive patients not receiving any drug treatment were given 150 mL twice daily of either L. helveticus LBK-16H fermented milk with a high concentration of tripeptides (Ile-Pro-Pro 7.5 mg/100 g and Val-Pro-Pro 10 mg/100 g) or a control product, for 10 weeks after a 4-week run-in period. Twenty-four-hour ABPM were taken at the beginning and at the end of the intervention period. The average baseline systolic and diastolic BP values were 132.6 +/- 9.9/83.0 +/- 8.0 mm Hg in the L. helveticus group and 130.3 +/- 9.6 /80.2 +/- 7.0 mm Hg in the control group. RESULTS: There was a mean difference of -4.1 +/- 0.9 mm Hg in systolic (P = .001) and a -1.8 +/- 0.7 mm Hg in diastolic BP (P = .048) between the L. helveticus group and the control group. There was no difference in the sum of the adverse events (P = .820). CONCLUSIONS: Lactobacillus helveticus LBK-16H fermented milk containing bioactive peptides, in daily use, does have a BP-lowering effect in hypertensive subjects and is thus a potential for the dietary treatment of hypertension.

Analysis of Variance↗

PubMed2005

Prosthetic radioiodination of interleukin-8 ([(123/131)I]-IL-8): biological behavior in a mouse infection model.

Numerous molecular entities with diverse structures have been radiolabeled and investigated as potential infection and inflammation detection agents. However, none of these molecules have gained the acceptance of gallium citrate or radiolabeled autologous white blood cells. We have radioiodinated interleukin-8 using two different methods and tested the biological behavior of the products in mice. As expected, the direct radioiodinated material displayed extensive in vivo deiodination. The use of pyridine-based prosthetic label yielded a product with better kinetics than the direct radioiodination method and showed a better target to non-target ratio. Nonetheless, this method is not suited for labeling of bioactive peptides such as the title peptide because of the very high specific activity required to prevent cytotoxic effects in a human application.

Animals↗

PubMed2005

Cloning and characterization of the human and rabbit NUDEL-oligopeptidase promoters and their negative regulation.

NUDEL-oligopeptidase is a cytosolic cysteine peptidase, active towards oligopeptides and involved in the conversion and inactivation of a number of bioactive peptides. This protein interacts with neuronal proteins and is essential for brain development and cortical organization during embryogenesis. In this study, 5'-flanking sequences of the human and rabbit NUDEL-oligopeptidase gene were cloned into the pGL3 reporter gene vector and the promoter activity of the full-length fragment and deletions series was measured in transient transfection assays using two different cell lines, namely, C6 rat glioma and NH15 human neuroblastoma. Overall, a very similar pattern of promoter activity was obtained for both rabbit and human NUDEL-oligopeptidase promoter sequences, and their respective serial deletion constructs upon transient transfection into these cell lines. The only exception was for the longest rabbit upstream sequence that displayed about 1.8-fold higher luciferase expression upon transfection into NH15 neuronal cells than that observed upon transfection into C6 glioma cells. On the other hand, no significant difference was observed for the human longest sequence. These results are in good agreement with the expression pattern of NUDEL-oligopeptidase in human and rabbit tissues.

Animals↗

PubMed2004

Adrenomedullin induces matrix metalloproteinase-2 activity in rat aortic adventitial fibroblasts.

BACKGROUND: The delicate balance of the extracellular matrix (ECM) determines the stiffness of the vascular wall, and adventitial fibroblasts are involved in ECM formation by synthesizing and degrading matrix proteins. In the present study, we examined the effect of the bioactive peptide adrenomedullin (AM) on activity and expression of matrix metalloproteinases (MMPs) in cultured aortic adventitial fibroblasts. METHODS AND RESULTS: In cultured adventitial fibroblasts isolated from aorta of adult Wistar rats, 10(-6)mol/L angiotensin II (Ang II) significantly (p<0.05) down-regulated MMP-2 activity as determined by in vitro gelatin zymography. In contrast, 10(-7)mol/L synthetic rat AM significantly (p<0.05) stimulated zymographic MMP-2 activity by 23%, increasing intracellular cAMP, and AM abolished the action of Ang II, augmenting the MMP-2 activity. Similarly, Ang II down-regulated MMP-2 protein expression assessed by Western blotting, whereas AM increased it. Furthermore, 8-bromo-cAMP, an analogue of cAMP, mimicked the effect of AM, and H-89, an inhibitor for protein kinase A (PKA), significantly decreased the basal and AM-induced MMP-2 activity. CONCLUSION: This study provides a new insight into the biological action of AM and its intracellular signaling system of cAMP/PKA stimulating the matrix degrading enzyme MMP-2, suggesting an important role for this molecule in modulating ECM deposition in the adventitial layer.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed2006

Isolation and identification of proangiotensin-12, a possible component of the renin-angiotensin system.

The renin-angiotensin (RA) system plays an important role in regulating blood pressure and fluid balance. In the search for bioactive peptides with an antibody binding to the N-terminal portion of angiotensin II (Ang II), we isolated a new angiotensinogen-derived peptide from the rat small intestine. Consisting of 12 amino acids, this peptide was termed proangiotensin-12 based on its possible role of an Ang II precursor. Proangiotensin-12 constricted aortic strips and, when infused intravenously, raised blood pressure in rats, while both the vasoconstrictor and pressor response to proangiotensin-12 were abolished by captopril and by CV-11974, an Ang II type I receptor blocker. Proangiotensin-12 is abundant in a wide range of organs and tissues including the small intestine, spleen, kidneys, and liver of rats. The identification of proangiotensin-12 suggests a processing cascade of the RA system, different from the cleavage of angiotensinogen to Ang I by renin.

Amino Acid Sequence↗

PubMed2006

Toxin insights into nicotinic acetylcholine receptors.

Venomous species have evolved cocktails of bioactive peptides to facilitate prey capture. Given their often exquisite potency and target selectivity, venom peptides provide unique biochemical tools for probing the function of membrane proteins at the molecular level. In the field of the nicotinic acetylcholine receptors (nAChRs), the subtype specific snake alpha-neurotoxins and cone snail alpha-conotoxins have been widely used to probe receptor structure and function in native tissues and recombinant systems. However, only recently has it been possible to generate an accurate molecular view of these nAChR-toxin interactions. Crystal structures of AChBP, a homologue of the nAChR ligand binding domain, have now been solved in complex with alpha-cobratoxin, alpha-conotoxin PnIA and alpha-conotoxin ImI. The orientation of all three toxins in the ACh binding site confirms many of the predictions obtained from mutagenesis and docking simulations on homology models of mammalian nAChR. The precise understanding of the molecular determinants of these complexes is expected to contribute to the development of more selective nAChR modulators. In this commentary, we review the structural data on nAChR-toxin interactions and discuss their implications for the design of novel ligands acting at the nAChR.

Animals↗

PubMed2003

Application of a novel design paradigm to generate general nonpeptide combinatorial scaffolds mimicking beta turns: synthesis of ligands for somatostatin receptors.

Nonpeptide compounds that mimic bioactive peptides are desirable for a number of clinical indications. We report a new practical method for the design of scaffolds exhibiting drug-like properties that are suitable for the display of peptide pharmacophores. The synthesis of various synthons of 7'-hydroxy-2',3'-dihydro-1'H,2H,5H-spiro[imidazolidine-4,4'-quinoline]-2,5-dione (1) and methods for the introduction of several mimics of amino acid side-chains are described. This method is exemplified by derivatives that show agonist activity for the somatostatin type 2 receptor.

Combinatorial Chemistry Techniques↗

PubMed2005

A new strategy for glycoprotein synthesis: ligation of synthetic glycopeptides with truncated proteins expressed in E. coli as TEV protease cleavable fusion protein.

We report here the use of TEV protease cleavable fusion proteins to produce glycosylated bioactive peptides and proteins. Bacterial expression was utilized to produce two fusion proteins, GPRT-C37-H6 and His-tagged interleukin-2 (amino acids 6-133), which when cleaved by the tobacco etch virus NIa protease (TEV protease) to generate HIV entry inhibitor peptide C37-H6 and a truncated version of the cytokine interleukin-2, both containing N-terminal cysteines. The N-terminal cysteine containing C37-H6 and truncated interleukin-2 were then joined to a synthetic glycopeptide thioester utilizing native chemical ligation under nondenaturing and denaturing conditions, respectively. The ligations of the glycopeptide to the C37-H6 peptide and the truncated interleukin-2 protein both proceeded in high yield, though the size, and physical properties of the two polypeptides differ greatly.

Base Sequence↗

PubMed2006

Expression of prokineticin receptors in mouse cultured astrocytes and involvement in cell proliferation.

Effects of prokineticins (PKs), a novel family of bioactive peptides with a mitogenic action to endothelial cells of the endocrine gland and testis, on astrocytic functions were examined. Mouse cultured astrocytes expressed PK-R1 type PK receptors, while there was little expression of the PK-R2 type. PKs caused increases in astrocytic cytosolic Ca2+ levels and BrdU incorporation. Increases in Ca2+ levels by PK-2 were diminished by U73122 (a phospholipase C inhibitor). PK-induced BrdU incorporation was inhibited by U73122, GF109203 (a protein kinase C inhibitor) and PD98059 (a MEK/ERK inhibitor). These results indicate that PK receptors are expressed in astrocytes and regulate astrocytic proliferation.

Animals↗

PubMed2006

Pathways of matrix metalloproteinase induction in heart failure: bioactive molecules and transcriptional regulation.

The structural basis for the development of congestive heart failure (CHF) is a maladaptive myocardial remodeling process which occurs secondarily to post-myocardial infarction (MI), hypertensive hypertrophy, or cardiomyopathy. Both cellular and extracellular factors are involved in the remodeling process and it is the combined action of these factors giving rise to changes in myocardial structure which eventually affects function. One component in this remodeling process is a family of extracellular matrix degrading enzymes, the matrix metalloproteinases or MMPs. Many bioactive molecules such as cytokines/chemokines, bioactive peptides, and neurohormones which are operative in CHF likely contribute to the induction of MMPs. For example, a specific cassette of transcription factors is likely induced with extracellular stimuli in the context of CHF which in turn induces MMPs and contributes to the maladaptive remodeling process. This review will briefly discuss the biology of the MMP family, but will more importantly identify how biological factors active in CHF result in the modulation of the MMP family. Understanding how upstream molecules are involved in MMP regulation/dysregulation may provide an avenue to develop important therapeutic interventions.

Animals↗

PubMed2006

ACE2 of the heart: From angiotensin I to angiotensin (1-7).

Angiotensin II (Ang II), a bioactive peptide of the renin-angiotensin system (RAAS), plays an important role in the development of cardiovascular diseases (CVD). Pharmacological inhibition of angiotensin-converting enzyme (ACE), the Ang II forming enzyme, or specific blockade of Ang II binding to angiotensin type 1 receptor (AT1R) through which it exerts its deleterious effects, were shown to provide some protection against progression of CVD. The ACE-Ang II-AT1R axis has been challenged over the last few years with RAAS components able to counterbalance the effects of the main axis. The ACE homologue ACE2 efficiently hydrolyses Ang II to form Ang (1-7), a peptide that exerts actions opposite to those of Ang II. In contrast to the Ang II axis, the role of the ACE2-Ang (1-7) axis in cardiac function is largely obscure. Ang (1-7) is present in the viable myocardium, and its formation depends on Ang II as a substrate. The expression of this peptide is associated with cardiac remodeling: it is lost in the infarcted area and significantly increased in the border area. Low doses of Ang (1-7) improve cardiac output and antagonize Ang II-induced vasoconstriction. The type of Ang (1-7) biological activity is tissue specific and dose dependent. These findings point to a possible protective role for Ang (1-7) in abating the Ang II-induced actions. The elevated expression of Ang (1-7) in failing heart tissue paralleled the expression of its forming enzyme, ACE2. Several observations and experimental evidence suggest a beneficial role for ACE2 in cardiovascular function. Elevated ACE2 expression at the initial stage of several pathologies which decline with progression of disease might indicate a protective role for ACE2. Genetic manipulation of ACE2 expression, either targeted disruption or overexpression, point to the possible significance of this enzyme in cardiac function. Based on the above, a therapeutic approach that will amplify the ACE2-Ang (1-7) axis could provide further protection against the development of CVD. It turns out that the merits of currently used drugs--ACE inhibitors, AT1R blockers and mineralocorticoid receptor blockers (MRB) - lay beyond their direct effects on suppression of the ACE-Ang II-AT1R axis as they also increase cardiac ACE2 and Ang (1-7) significantly.

Angiotensin I↗

PubMed2005

Applications of carbon nanotubes in drug delivery.

The development of new and efficient drug delivery systems is of fundamental importance to improve the pharmacological profiles of many classes of therapeutic molecules. Many different types of drug delivery systems are currently available. Within the family of nanomaterials, carbon nanotubes (CNT) have emerged as a new alternative and efficient tool for transporting and translocating therapeutic molecules. CNT can be functionalised with bioactive peptides, proteins, nucleic acids and drugs, and used to deliver their cargos to cells and organs. Because functionalised CNT display low toxicity and are not immunogenic, such systems hold great potential in the field of nanobiotechnology and nanomedicine.

Drug Delivery Systems↗

PubMed2005

Hen egg white fractionation by ion-exchange chromatography.

Major hen egg white proteins have been widely studied for their functional properties but these studies still are unable to explain, alone, all of the biological properties of hen egg white. Hence, it is still interesting to produce pure and non-altered proteins to improve our knowledge on the biological properties of hen egg white. Presently, identification and characterization of both bioactive peptides and minor proteins from hen egg white is essential work for progressing in the understanding of hen egg white biological properties. With this objective in mind, a new process for a complete "mucin free" hen egg white fractionation based on ion exchange chromatography is proposed. "Mucin free" egg white is fractionated into six different fractions. Four of them are high-recovery yield purified fractions of lysozyme, ovotransferrin, ovalbumin and flavoprotein. The two other fractions are enriched in recently detected minor proteins in hen egg white.

Animals↗

PubMed2006

Dose-related actions of GnRH II analog in the cycling rhesus monkey.

INTRODUCTION: Gonadotropin-releasing hormone (GnRH) II expression, specific high-affinity receptors for GnRH II and its potent bioactivity in human and baboon tissues led us to hypothesize that GnRH II is a bioactive peptide in primates. We recently demonstrated the contraceptive activity of GnRH II analog in rhesus monkeys. In the present experiment, we extended those studies to the dose-related action of this analog on parameters of luteal function and conception. METHODS: GnRH II analog (0-32 microg/day) or saline was administered via osmotic minipumps for 6 days (Days 1-6 postovulation) to regularly cycling rhesus monkeys mated with fertile males around the time of ovulation. Cycle dynamics was monitored through circulating luteinizing hormone, progesterone and estradiol. Pregnancy was determined by circulating chorionic gonadotropin concentrations. RESULTS: Progesterone production (Days 3-11) was significantly less (p<.05) for animals treated with 2, 4 or 8 microg/mL GnRH II analog than for controls, yet with higher doses of GnRH II analog (i.e., 16 or 32 microg/day), luteal progesterone was not different from that of saline-treated controls. The length of the luteal phase in all treated groups was similar to that of controls. In 18 animals mated at the time of ovulation and then treated with GnRH II analog (2-32 microg/day), no pregnancies resulted. In saline-treated controls, five of eight animals (62.5%) became pregnant. Thus, the contraceptive activity of this GnRH II analog did not correlate with luteal progesterone inhibition. CONCLUSIONS: These data demonstrate a dose-related action of GnRH II analog on luteal progesterone and establish the contraceptive activity of 2-32 microg/day GnRH II analog administered postovulation.

Animals↗

PubMed2005

Fermented functional foods based on probiotics and their biogenic metabolites.

The claimed health benefits of fermented functional foods are expressed either directly through the interaction of ingested live microorganisms, bacteria or yeast with the host (probiotic effect) or indirectly as a result of ingestion of microbial metabolites produced during the fermentation process (biogenic effect). Although still far from fully understood, several probiotic mechanisms of action have been proposed, including competitive exclusion, competition for nutrients and/or stimulation of an immune response. The biogenic properties of fermented functional foods result from the microbial production of bioactive metabolites such as certain vitamins, bioactive peptides, organic acids or fatty acids during fermentation.

Animals↗