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At least 325 records · Page 18Linked to original sources
PubMed1999

Bioactive antinutritional peptides derived from cereal prolamins: a review.

Alcohol-soluble endosperm proteins (prolamins) from some cereals (e.g. wheat, barley, and rye) give origin upon proteolytic digestion to biologically-active antinutritional peptides able to adversely affect in vivo the intestinal mucosa of coeliac patients, whereas prolamins from other cereals (e.g. maize and rice) do not. These antinutritional peptides are also able to: (a) prevent in vitro recovery of atrophic coeliac mucosa; (b) to inhibit differentiation of isolated rat fetal and chick fetal intestines; and (c) to interact with undifferentiated cells either agglutinating them or affecting their proliferation and metabolism. Studies performed with A-gliadin, a highly purified bread wheat prolamin fraction, and its fragments obtained either by chemical cleavage of A-gliadin or by synthesis from aminoacids, clearly pointed out to a few small sequences very rich in glutamine and proline residues as the biologically-active agents. Several protective substances, including mannan and N,N',N"-triacetylchitotriose, have been identified as being able to prevent the effects of these peptides in vitro, but the evidence of their in vivo activity is still missing. The present paper provides a synthetic overview of the available data concerning this highly complex matter and offers a critical appraisal of present hypotheses on the action mechanism of biologically-active peptides derived from cereal prolamins.

Amino Acid Sequence↗
PubMed2006

Design of a minimized cyclic tetrapeptide that neutralizes bacterial endotoxins.

Septic shock is a leading cause of mortality in intensive care patients, and no specific drugs are as yet available for its treatment. Therefore, new leads are required in order to increase the number of active molecules that may develop into efficacious and safe LPS-neutralizing molecules during pre-clinical stages. We used peptides, derived from the binding regions of known LPS-binding proteins, as scaffolds to introduce modifications at the amino acid level. Structure-activity relationship studies have shown that these modifications generate highly active peptides. Thus, from a bioactive peptide with an initial 16 amino acid residues, a tetrapeptide sequence was determined. After inserting this sequence in a Cys cyclic peptide, it showed the same biological activity as the parent peptide. This sequence could provide the basis for the design of small molecules with LPS-binding properties.

Amino Acid Sequence↗
PubMed2001

Bioactive dahlein peptides from the skin secretions of the Australian aquatic frog Litoria dahlii: sequence determination by electrospray mass spectrometry.

Eleven dahlein peptides are present in the skin secretion of the Australian aquatic frog Litoria dahlii. All peptides have been sequenced using a combination of electrospray mass spectrometry (ES-MS) and Lys-C digestion/MS, with each sequence confirmed by automated Edman sequencing. The 13-residue dahlein 1 peptides (e.g. dahlein 1.1 GLFDIIKNIVSTL-NH(2)) exhibit weak wide-spectrum antimicrobial activity but no significant activity in the anticancer testing program of the National Cancer Institute (Washington). There are no potent antimicrobial peptides present in the glandular secretion, but the dahleins 5 strongly inhibit the formation of NO by neuronal nitric oxide synthase (e.g. dahlein 5.1 GLLGSIGNAIGAFIANKLKP-OH).

Amino Acid Sequence↗
PubMed1995

Bioactive synthetic peptide of NDF/heregulin.

A folded synthetic peptide analog of NDF (NDF5), which has the 52 amino acid EGF-like domain of NDF alpha 2, has been characterized. The folded peptide stimulates tyrosine phosphorylation of Her2, Her3 and Her4 in breast cancer cells and competes with low affinity with full-length NDF alpha 2 for binding to the cells, while the linear one does not. NDF5 also induces morphologic changes in breast cancer cells. After several days treatment with NDF5 or NDF alpha 2, Her2-transfected MCF7 cells (Her2/MCF7) became similar morphologically to non-transfected MCF7. The biological activity of NDF5 is between 1/10 and 1/100 that of NDF alpha 2. This suggests that other motifs, such as the Ig and spacer domains may be important elements in conferring full activity.

Amino Acid Sequence↗
PubMed1984

The sequence of an atriopeptigen: a precursor of the bioactive atrial peptides.

The high molecular weight fraction ( atriopeptigen -APG) obtained by gel filtration chromatography of rat atrial extracts was fractionated by isoelectric focusing and reverse phase HPLC to obtain a pure APG. Purification of cyanogen bromide digests of the crude high molecular weight fraction resulted in the isolation of a single biologically active cyanogen bromide cleavage peptide. Sequence analyses of these peptides coupled with recent reports of sequence analyses of intermediate molecular weight atrial peptides ( Thibault , et al. (1984) FEBS Letters 167, 352-356, and Kangwa , et al., Biochem. Biophys. Res. Commun 119, 933-940) provide the complete primary structure of an 111 residue APG.

Amino Acid Sequence↗
PubMed2006

Affinity purification of angiotensin converting enzyme inhibitory peptides using immobilized ACE.

A lung extract rich in angiotensin converting enzyme (ACE) and pure ACE were immobilized by reaction with the activated support 4 BCL glyoxyl-agarose. These immobilized ACE derivatives were used for purification of ACE inhibitory peptides by affinity chromatography. The immobilized lung extract was used to purify inhibitory peptides from sunflower and rapeseed protein hydrolysates that had been obtained by treatment of protein isolates with alcalase. The ACE binding peptides that were retained by the derivatives were specifically released by treatment with the ACE inhibitor captopril and further purified by reverse-phase C18 HPLC chromatography. Inhibitory peptides with IC50 50 and 150 times lower than those of the original sunflower and rapeseed hydrolysates, respectively, were obtained. The derivative prepared using pure ACE was used for purification of ACE inhibitory peptides from the same type of sunflower protein hydrolysate. ACE binding peptides were released from the ACE-agarose derivatives by treatment with 1 M NaCl and had an IC50 a little higher than those obtained using immobilized extract and elution with captopril. Affinity chromatography facilitated the purification of ACE inhibitory peptides and potentially other bioactive peptides present in food proteins.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1994

A bioactive fullerene peptide.

The highly hydrophobic C60 (buckminsterfullerene) was water solubilized by covalently linking the synthon 1,2-dihydro-1,2-methanofullerene [60]-61-carboxylic acid to the alpha-amino group of the hydrophilic 4-8 sequence of peptide T, known to display potent human monocyte chemotaxis. The resulting compound, characterized by a variety of analytical techniques, including a UV spectrum in aqueous solution, exhibits remarkable chemotactic potency, comparable to that of the parent pentapeptide. Furthermore, this fullerene-peptide conjugate inhibits, albeit weakly, HIV-1 protease.

Amino Acid Sequence↗
PubMed1996

Keenamide A, a bioactive cyclic peptide from the marine mollusk Pleurobranchus forskalii.

Keenamide A (1), a new cytotoxic cyclic hexapeptide, was isolated from the notaspidean mollusk Pleurobranchus forskalii. Its structure was determined by NMR spectral data interpretation and chiral amino acid analysis. Keenamide A (1) exhibited significant activity against the P-388, A-549, MEL-20, and HT-29 tumor cell lines, but was inactive when evaluated against the D6 and W2 Plasmodium falciparum malarial clones.

Animals↗
PubMed2005

Bioactive cyclic peptides from the psychrotolerant fungus Penicillium algidum.

A new cyclic nitropeptide, psychrophilin D (1), together with two known cyclic peptides, cycloaspeptide A (2) and cycloaspeptide D (3), were isolated from the psychrotolerant fungus Penicillium algidum using C18 flash chromatography, LH-20 Sephadex and preparative HPLC. The structure of psychrophilin D (1) was derived from mass spectrometric information, 1D and 2D NMR spectra and Marfey's method. The compounds were tested in antimicrobial, antiviral, anticancer and antiplasmodial assays. Psychrophilin D (1) exhibited a moderate activity (ID50 10.1 microg/ml) in the P388 murine leukaemia cell assay. Cycloaspeptide A (2) and D (3) exhibited moderate activity (IC50 3.5 and 4.7 microg/ml, respectively) against Plasmodium falciparum.

Animals↗
PubMed1998

Bioactive angiotensin peptides.

Angiotensin II is recognised as the principle active peptide of the renin-angiotensin system, exerting effects on fluid and electrolyte homeostasis, and cardiovascular control including neural and long term trophic effects. However, recent studies indicate that other angiotensin peptides such as angiotensin III, angiotensin II (1-7) and angiotensin IV, may have specific actions. Interestingly, recent work involving angiotensin IV demonstrates that this peptide binds to specific receptors and may be involved in memory retention and neuronal development. Furthermore, our demonstration that a globin fragment, LVV-haemorphin-7, binds with high affinity to the angiotensin IV binding site and is abundant in the brain, indicates that this may represent a novel brain neuropeptide system. It now appears, that the renin-angiotensin system is more complex than previously thought and capable of generating multiple, active peptides which elicit numerous diverse actions.

Angiotensin II↗
PubMed1984

Proteolytic activation of a bioactive cardiac peptide by in vitro trypsin cleavage.

Mammalian cardiac atria possess several unidentified biologically active peptides. Fractionation of rat atrial extracts by gel filtration chromatography revealed two major fractions [apparent molecular weights of 20,000-30,000 (peak I) and less than 10,000 (peak II)], both of which were potent natriuretic agents (eliciting a 25-fold increase in sodium excretion) and smooth muscle relaxants. Vigorous treatment with trypsin (100 units/ml at 37 degrees C for 15 min) of both fractions abolished all biological activity. Further purification of the lower molecular weight fraction (peak II) by ion-exchange chromatography indicated two subfractions that possessed potent natriuretic activity and that preferentially relaxed either intestinal (designated peak IIA) or vascular (peak IIB) smooth muscle assay tissues. The similarity of the biological effect of the high (peak I) and low (peak II) molecular weight peptides led us to test the possibility of precursor-product relationship. Mild proteolytic treatment of the high molecular weight peptide with trypsin (1 unit/ml at room temperature) markedly enhanced the smooth muscle relaxant activity. Subsequent analysis of the trypsin (1 unit/ml)-treated high molecular weight peptide (peak I) by gel filtration and ion-exchange chromatography revealed that the peptide now resembled the low molecular weight peptides (peaks IIA and IIB) present in the original atrial extract. These data suggest that the cardiac atria contain a relatively inactive (smooth muscle relaxant) high molecular weight peptide and suggest that biologically active low molecular weight peptides can subsequently be generated by proteolytic cleavage.

Animals↗
PubMed1994

Interaction of bioactive hydrophobic peptides with the human multidrug transporter.

In this report we demonstrate that various biologically active hydrophobic peptide derivatives, e.g., proteinase inhibitors, chemoattractants, ionophores, enkephalins, and immunosuppressants, stimulate a membrane ATPase activity associated with the human multidrug transporter (MDR1). The stimulation of the MDR1-ATPase by these agents does not correlate with their known biochemical or pharmacological activities but rather with their hydrophobicity. The peptides that show high-affinity interaction with the MDR1-ATPase also interfere strongly with fluorescent dye extrusion catalyzed by the multidrug transporter in intact cells and some have been shown to reverse drug resistance in cultured cells. These data suggest that several hydrophobic peptides behave as substrates of the multidrug transporter and may be used to modulate the chemotherapy resistance of tumor cells.

3T3 Cells↗
PubMed1984

Purification and sequence analysis of bioactive atrial peptides (atriopeptins).

Mammalian cardiac atria have several biologically active peptides that exert profound effects on sodium excretion, urine volume, and smooth muscle tone. In the present study two such peptides of low molecular weight were purified and separated from each other on the basis of differences in charge, hydrophobicity, and biological profile. The first peptide, designated atriopeptin I, exhibits natriuretic and diuretic activity and selectivity relaxes intestinal smooth muscle but not vascular smooth muscle strips. The second peptide, atriopeptin II, is a potent natriuretic and diuretic that relaxes both intestinal and vascular strips. Sequence analysis of atriopeptin I indicates that it is composed of 21 amino acids, of which serine and glycine residues predominate. The amino terminal sequence of atriopeptin II up to residue 21 is the same as that of atriopeptin I, with the addition of the Phe-Arg extension at the carboxyl terminus. Both peptides appear to be derived from a common high molecular weight precursor (designated atriopeptigen); their biological selectivity and potency may be determined by the site of carboxyl terminal cleavage.

Amino Acid Sequence↗
PubMed2002

Increased expression of dipeptidyl peptidase IV in human mesothelial cells by malignant ascites from ovarian carcinoma patients.

Cell surface aminopeptidases play an important role in biological processes through degradation of small peptides. There are many bioactive peptides in ascites and these peptides are involved in carcinoma cell dissemination and infiltration. In human mesothelial cells dipeptidyl peptidase IV (DPPIV) shows the highest expression mostly in four cell surface aminopeptidases: aminopeptidase A, neutral endopeptidase 24-11, aminopeptidase N and DPPIV. Since mesothelial cells are always in contact with ascites, we examined the influence of malignant ascites on DPPIV. DPPIV enzyme activity in mesothelial cells was enhanced by the addition of ascites obtained from ovarian carcinoma patients in a time- and concentration-dependent manner, and flow cytometry and immunocytochemistry also revealed an increased expression of DPPIV on the cell surface of mesothelial cells. The <3-kD fraction of malignant ascites increased the DPPIV enzyme activity to the same level as the total ascites. Northern hybridization demonstrated that DPPIV mRNA was increased 3-fold by the addition of the <3-kD malignant ascites. In conclusion, DPPIV is highly expressed in human mesothelial cells and was regulated by ascites.

Aminopeptidases↗
PubMed2003

Biosynthesis of proopiomelanocortin-derived peptides in prohormone convertase 2 and 7B2 null mice.

Prohormone convertases (PCs) are thought to represent the major proteinases involved in the biosynthetic processing of peptide hormone precursors to bioactive peptide products. The maturation of PC2 requires the aid of a helper protein, 7B2, in order for the zymogen to become an active enzyme species. The 7B2 and PC2 nulls should thus be functionally equivalent with regard to deficits in precursor processing. In this article, we have examined this proposition through the study of proopiomelanocortin (POMC) biosynthesis and granule content in both null models. RIA data indicate that both PC2 and 7B2 nulls lack pituitary alpha-MSH; interestingly, 7B2 nulls are still able to generate beta-endorphin from beta-lipotropin, whereas PC2 nulls contain little if any beta-endorphin. Labeling experiments demonstrate a build-up of POMC, high molecular weight intermediates, and intact ACTH, as well as the disappearance of alpha-MSH, in both null models. Electron microscopy of neurointermediate lobe melanotrophs reveals the presence of a significantly greater number of secretory granules in both 7B2 and PC2 nulls compared with wild-type controls. However, PC2 null melanotrophs contain twice as many granules as 7B2 null melanotrophs. Another difference between the two null models is a relatively enhanced accumulation of precursors in the PC2 null compared with the 7B2 null; these include not only PC2 substrates, but also presumed PC1 substrates. These data indicate that the two nulls are not phenotypically equivalent.

Adrenocorticotropic Hormone↗
PubMed1992

Deficiency of acylpeptide hydrolase in small-cell lung carcinoma cell lines.

During protein biosynthesis, processing of the N terminus of many proteins may occur through acetylation and deacetylation. The enzyme acylpeptide hydrolase is likely involved in deacetylation of nascent peptide chains or of bioactive peptides. The related enzyme, acylase, hydrolyzes the acetyl amino acid product of the acylpeptide hydrolase reaction to acetate and a free amino acid. There is a reciprocal relationship between the substrates for these enzymes (i.e., substrates for one enzyme are competitive inhibitors for the other). In several cultured cell lines, including normal and malignant cells, the ratio of acylpeptide hydrolase to acylase enzyme activities appears to be coordinated and characteristic for a given cell type. Thus, in normal cultured lung cells, hamster ovary cells, hepatoma cells, and lymphocyte cells, nearly equal amounts of these enzymes are expressed, conducive to optimal processing of acetylated N-terminal residues. Four lines of erythroleukemic cell lines were found to express nearly twice as much acylase as acylpeptide hydrolase activity. In the Ehrlich ascites tumor cell line, where 80% of the proteins have been reported to remain acetylated at their N terminus, acylpeptide hydrolase is hardly expressed but acylase activity is not reduced. The 3p21 region of human chromosome 3, which contains the DNF15S2 locus that encodes acylpeptide hydrolase (Jones et al., Proc Natl Acad Sci USA 1991;88:2194), undergoes deletion in some carcinoma cells; the gene that encodes for the acylase is also present on region 3p of the same chromosome. We found that both acylpeptide hydrolase and acylase activities are practically absent in six small-cell lung carcinoma cell lines tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Amidohydrolases↗