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PubMed2006

Development of affinity chromatography using a bioactive peptide as a ligand.

By repeatedly introducing hydrophilic polyethylene glycol (PEG) spacer (2) onto affinity resin bearing a bioactive peptide (1/2 secretory leukocyte protease inhibitor, 1/2SLPI) as a ligand, the adsorption of nonspecific binding proteins was effectively reduced and the purification efficacy of elastase, which is one of the target molecules for 1/2SLPI, from a protein mixture was improved. Moreover, using this resin, we also successfully detected L-plastin, as an endogenous target molecule for SLPI, from HL-60 cell lysate.

Adsorption↗

PubMed1995

Sensitivity and selectivity of the electrochemical detection of the copper(II) complexes of bioactive peptides, and comparison to model studies by rotating ring-disc electrode.

Post-column reaction of peptides with Cu(II) can be used for the electrochemical detection of peptides as their biuret complexes. Understanding of the behavior (sensitivity at the anode and cathode in the dual-series electrochemical detector) of the system is facilitated through the observation of the rotating ring disc voltammetry of some model compounds. In operation, the anodic signal from the oxidation of the Cu(II)-peptide to the Cu(III) form can be used to detect peptides, or the downstream cathode can be used to detect the Cu(III) form. The signals appear at about 0.4 V (anode) for tetra- and longer peptides, 0.65 V for tripeptides. The anode signal is augmented by tyrosine (oxidation at 0.4-0.5 V) and tryptophan (0.5-0.6 V). If the cathode is used as the detector in a two working electrode cell, the sensitivity depends on the stability of the Cu(III) product. This is peptide dependent, but the signal is significant and useful analytically. Twenty-three bioactive peptides in two groups, naturally electrochemically active and naturally electrochemically silent, and several model compounds have been studied. Both naturally electrochemically active peptides (contain tyrosine and/or tryptophan) and naturally electrochemically silent peptides have been studied. Chromatography with an acetonitrile gradient has been used to separate the peptides in each group. Detection limits are for non-electroactive peptides in the range of 16-100 fmol (10- microliters injection 1.6-10 nM, 100 microliters injection 0.16-1.0 nM), and for electroactive peptides in the range of 6-40 fmol (0.6-4.0 nM for a 10- microliters injection and 60-400 pM for a 100- microliters injection). A tryptic digest of bovine cytochrome c is easily seen at 100 nM.

Amino Acid Sequence↗

PubMed1989

Chemical characterization of bioactive peptides from in vivo digests of casein.

The in vivo formation of biologically active caseinopeptides was studied. It was proved that bioactive peptides were released in the small intestine of minipigs in the course of luminal digestion of diets containing bovine casein. An opioid peptide and a phosphopeptide were isolated from jejunal chyme and were chemically characterized. The opioid peptide has been identified as a fragment of beta-casein (60-70). This peptide, named beta-casomorphin-11, displayed substantial opioid activity in an opiate receptor-binding assay. The caseinophosphopeptide has been shown to be a fragment of alpha s1-casein (66-74). Casein-derived phosphopeptides exhibit a potent ability to form soluble complexes with Ca and trace elements. Evidence exists that casomorphins and caseinophosphopeptides participate in the regulation of nutrient entry.

Animals↗

PubMed2006

[Effects of anti-cancer bioactive peptide on cell cycle in human nasopharyngeal carcinoma strain CNE].

OBJECTIVE: To investigate effects of two kinds of anti-cancer bioactive peptide (ACBP) on proliferation and cell cycle in human nasopharyngeal carcinoma strain CNE. METHODS: Cell culture was used in vitro, CNE cells were exposed to different concentration ACBP, in all groups, contrast groups were set up. And 24, 48, 72 hours later, growth characteristics of CNE cells were studied by morphological observation and MTT assay . Cell cycle and apoptosis were analyzed by flow cytometry (FCM). RESULTS: In normal contrast group, CNE cells grew intensively and contacted with each other. However, cells which were treated with ACBP were inhibitory greatly in higher dose ACBP group, necrosis could be found. MTT assay showed that ACBP inhibited growth of CNE cell. FCM showed that ACBP (20.0 microg/ml) could raise cell ratio of S phase and induce apoptosis of CNE cells. CNE cells were treated by two kind of ACBP (5.0 microg/ml) for 24 h, FCM showed that early apoptosis rate were (11.8 +/- 0.3)% and (8.1 +/- 0.2)% respectively, which showed statistical significance in comparison with control group (t = 42.535, 47.300 respectively, P = 0.000). Under light microscope, some sings of cell apoptosis including coagulation of chromatin, fragmentation of nuclei and apoptotic body could be found. CONCLUSIONS: Two kinds of ACBP inhibited human nasopharyngeal carcinoma strain CNE proliferation and arrested the cells to S phase, also induced the cells to apoptosis. Nasopharyngeal neoplasms;

Apoptosis↗

PubMed2004

Synthesis and structural characterization of bioactive peptide conjugates using thioether linkage approaches.

Applications of cysteine-insertion and thioether linkage approaches to the preparation of a number of bioactive peptide conjugates are reported. Peptides containing epitopes from (i) herpes simplex virus type 1 glycoprotein D, (ii) a specific N-terminal beta-amyloid epitope recognized by therapeutically active antibodies, and (iii) a GnRH-III peptide from sea lamprey with antitumour activity, were elongated with Cys residues and attached to a chloroacetylated tetratuftsin derivative carrier via a thioether linkage either directly, or by insertion of a spacer. The structures and molecular homogeneity of all the peptide conjugates were ascertained by HPLC, MALDI and electrospray mass spectrometry. The use of a spacer such as an oligoglycine or GFLG-tetrapeptide gave an increased yield in the conjugation reaction and enhanced reaction rates. In the formation of cysteinyl-thioether linkages, it was found that the position of flanking Cys residues markedly influenced the conjugation reaction and the formation of intermolecular epitope disulfide-dimers. C-terminal Cys residues gave thioether conjugates with significantly diminished epitope-dimerization, while Cys at the N-terminal caused rapid disulfide-dimerization, thereby preventing efficient conjugation.

Acetates↗

PubMed1998

Solution structure and internal motion of a bioactive peptide derived from nerve growth factor.

The conformation and internal dynamics of a bioactive cyclic peptide, N-acetyl-YCTDEKQCY, derived from the C-D loop of beta-nerve growth factor (beta-NGF) were analyzed by solution NMR spectroscopy. NMR experimental data were used to calculate an ensemble of peptide structures. All of the structures had a beta-turn at residues Asp4-Gln7 but could be divided into two families according the presence or absence of a hydrogen bond at Gln7. Comparison of the calculated structures with the corresponding C-D loops from the x-ray structures of the NGF revealed striking similarity. The orientation of Glu5, Lys6, and Gln7 side chains in the NGF mimetic was very similar to the C-D loop of NGF. These residues are known to participate in interactions with the TrkA receptor. Relaxation measurements of the peptidomimetic alpha-carbons at 13C natural abundance and calculated dynamic parameters suggest that the loop region of peptide is well structured but that residues Thr3, Asp4, Glu5, and Lys6 undergo slow conformational exchange. These results suggest that conformational similarity and possibly peptide dynamics are responsible for the bioactivity of the peptide.

Amino Acid Sequence↗

PubMed2004

Casein proteolysis in human milk: tracing the pattern of casein breakdown and the formation of potential bioactive peptides.

The protein and peptide fraction of human milk samples collected from mothers of pre- and full-term infants in the first week after parturition was analysed by use of liquid chromatography-mass spectrometry and tandem mass spectrometry. By characterising the peptide sequence, we defined the pathway of casein hydrolysis which leads to the formation of small peptides through intermediate oligopeptides. It was found that the action of a plasmin-like enzyme acting on specific lysine residues is the primary step in casein degradation. This is followed by endopeptidases and/or exopeptidases mediated cleavage of the oligopeptides which, in turn, produces a multiplicity of short peptides differing by one or more amino acid residues. In this process, a series of potentially bioactive peptides (opioid, phosphopeptides) and their precursors are produced.

Amino Acid Sequence↗

PubMed1992

The presence of immunoreactive vertebrate bioactive peptide substances in hemocytes of the freshwater snail Viviparus ater (Gastropoda, Prosobranchia).

1. Using an immunocytochemical procedure a wide range of immunoreactive vertebrate bioactive peptides (BAPs) has been found in hemocytes of Viviparus ater: bombesin, calcitonin, CCK-8, CCK-39, GH, glucagon, insulin, oxytocin, neurotensin, secretin, serotonin, somatostatin, substance P, vasopressin, and VIP. 2. No immunostaining was observed for antigastrin and antithyroglobulin antibodies. 3. The presence of BAP-like molecules in hemocytes suggests a correlation between hemocyte and APUD cells and is evidence of a relationship between the neuroendocrine and the immune systems.

APUD Cells↗

PubMed1997

Analysis of bioactive peptides by liquid chromatography-high-resolution electrospray mass spectrometry.

LC-high-resolution electrospray ionization (ESI)-MS data for a number of bioactive peptides, including substance P and bradykinins were acquired over a wide mass range by scanning the magnetic sector and calibrating externally with polyethylene glycol standards. Multiply charged ions were observed and errors between observed and theoretical monoisotopic molecular masses were typically in the 5 to 30 ppm range for the peptides during LC-ESI-MS and ESI-MS operation with magnetic sector resolutions between 2500 and 6000 (10% valley definition). Under collisionally activated dissociation conditions bn- and yn-series sequence ions were generally observed, enabling amino acid sequencing and the differentiation of lysine from glutamine, two amino acids differing in residue mass by only 0.0364 u. Mass accuracy was evaluated during an international round robin analytical exercise where the molecular masses of five unknown peptides were to be accurately determined. Isotopic clusters for charge states of up to +6 were fully resolved, facilitating the rapid and unambiguous assignment of charge states and calculation of monoisotopic molecular masses. Errors between theoretical and observed monoisotopic molecular masses were in the 2 to 18 ppm range for the five unknown peptides.

Bradykinin↗

PubMed2002

Mimicry of bioactive peptides via non-natural, sequence-specific peptidomimetic oligomers.

Non-natural, sequence-specific peptidomimetic oligomers are being designed to mimic bioactive peptides, with potential therapeutic application. Cationic, facially amphipathic helical beta-peptide oligomers have been developed as magainin mimetics. Non-natural mimics of HIV-Tat protein, lung surfactant proteins, collagen, and somatostatin are also being developed. Pseudo-tertiary structure in beta-peptides and peptoids may herald the creation of entirely artificial proteins.

Amino Acid Sequence↗

PubMed2004

A kinetic study of bovine haemoglobin hydrolysis by pepsin immobilized on a functionalized alumina to prepare hydrolysates containing bioactive peptides.

The hydrolysis kinetics of native and denatured haemoglobin, using pepsin immobilized on aluminium oxide, was studied in order to produce hydrolysates containing bioactive peptides. Pepsin was immobilized on acidic alumina and on 2-ethanolamine- O -phosphate (2-EAOP)-modified acidic alumina. Surface charge of the two supports was determined as a function of pH. Kinetic studies were performed at 23 degrees C in 0.1 M acetate buffer, pH 4.5. At this pH, the surface charge of the two supports was almost the same. The coating of alumina by 2-EAOP only introduced a two carbon spacer between alumina surface and the reaction medium. Adsorption on the two supports of haemoglobin, haem and peptides produced in the course of hydrolyses were compared. Fixation of 2-EAOP on a pepsin-alumina complex gave hydrolysis kinetics of urea-denatured haemoglobin close to that obtained with the same amount of pepsin in solution, but with comparatively less adsorption of peptides and complete adsorption of haem. Heterogeneous hydrolyses of haemoglobin with pepsin, immobilized on functionalized alumina, resulted in the presence of VV-haemorphin-4, VV-haemorphin-7 and neokyotorphin in the supernatants without haem, the presence of which makes further purification difficult.

Aluminum Oxide↗

PubMed2002

Possible role of bioactive peptides in the regulation of human detrusor smooth muscle - functional effects in vitro and immunohistochemical presence.

Results from basic research implicate a role for bioactive peptides in controlling the mammalian lower urinary tract. Although various peptides are assumed to be involved in the potentiaton or inhibition of cholinergic or purinergic activity in the urinary bladder, there is still much controversy regarding the mode of action and functional significance of such peptides in detrusor smooth muscle. Thus, we evaluated the functional effects of atrial natriuretic peptide (ANP), calcitonin gene related peptide (CGRP), endothelin 1 (ET-1), substance P (SP) and vasoactive intestinal polypeptide (VIP) on isolated strip preparations of human detrusor smooth muscle and determined the presence of those peptides in the human detrusor by means of immunohistochemistry. The effects of peptides on isometric tension of isolated detrusor strip preparations and on tissue levels of cyclic nucleotides cAMP and cGMP were compared to those of adenylyl cyclase activator forskolin (F), nitric oxide donor Na(+)-nitroprusside (SNP) and non-specific phosphodiesterase (PDE) inhibitor papaverine (P). The effects of the compounds on isometric tension of isolated human detrusor smooth muscle were examined using the organ bath technique. To determine time- and dose-dependent effects on cyclic nucleotide levels, bladder strips were exposed to increasing doses of F, SNP, P, ANP, CGRP and VIP, then rapidly frozen in liquid nitrogen and homogenised in the frozen state. cAMP and cGMP were extracted and assayed using specific radioimmunoassays. The presence of peptides was investigated by light microscopy using the Avidin-Biotin-Complex (ABC) method. F, P and VIP most effectively reversed the carbachol-induced tension of isolated human detrusor strips. Relaxing effects of ANP, CGRP and SNP were negligible. In contrast, ET-1 and SP elicited dose-dependent contractions of the tissue. The relaxing effects of F, P and VIP were accompanied by an increase in cAMP and cGMP levels, respectively. Light microscopy revealed positive immunostaining for CGRP, ET 1, VIP and SP in sections of the detrusor muscle coat. Our results suggest a possible importance of ET 1, SP and VIP in regulating detrusor smooth muscle contraction and relaxation. Even if a peptide is not synthesised, stored or released in a smooth muscle tissue and is, therefore, unable to reach its target cells under physiologic conditions, a functional effect on the tissue might be mediated by peptide-binding to specific cell surface receptors.

Atrial Natriuretic Factor↗

PubMed2006

Simultaneous separation of acid and basic bioactive peptides by electrodialysis with ultrafiltration membrane.

beta-Lactoglobulin (beta-lg), one of the major whey components, can release by enzymatic hydrolysis different bioactive peptidic sequences according to the enzyme used. However, these protein hydrolysates have to be fractionated to obtain peptides in a more purified form. The aim of the present work was to evaluate the feasibility of separating peptides from a beta-lg hydrolysate using an ultrafiltration (UF) membrane stacked in an electrodialysis (ED) cell and to study the effect of pH on the migration of basic/cationic and acid/anionic peptides in the ED configuration. Electrodialysis with ultrafiltration membrane (EDUF) appeared to be a selective method of separation since amongst a total of 40 peptides in the raw hydrolysate, only 13 were recovered in the separated adjacent solutions (KCl 1 and KCl 2). Amongst these 13 migrating peptides, 3 acid/anionic peptides migrated only in one compartment (KCl 1), while 3 basic/cationic peptides migrated only in the second compartment (KCl 2) and that whatever the pH conditions of the hydrolysate solution. Furthermore, the highest migration was obtained for the ACE-inhibitory peptide beta-lg 142-148, with a value of 10.75%. The integrity of the UF membrane was kept and EDUF would minimize the fouling of UF membrane.

Animals↗

PubMed1999

On the structural stability of a small bioactive peptide of potential use in biotechnology.

A tridecapeptide with the sequence CCEICCNPACFGC has been synthesized to reproduce the active moiety of a heat stable enterotoxin from Vibrio cholerae. The proton NMR analysis indicates, for the active synthetic fragment, a rigid secondary structure stabilised by three disulfide bridges. Such a rigid peptide, suitably detoxified and activated, could be a good candidate to be used as a carrier for linear bioactive peptides or other functional groups.

Biotechnology↗

PubMed2002

Stability of protein-bound conformations of bioactive peptides: the folded conformation of an epidermal growth factor-like thrombomodulin fragment is similar to that recognized by thrombin.

The relationship between the free and bound conformations of bioactive peptides is explored using the epidermal growth factor (EGF)-like thrombomodulin fragment hTM409-426 as a model system. The hTM409-426 peptide has a sequence of C(409)PEGYILDDGFIC(421)TDIDE (with a disulfide bond between Cys409 and Cys421) and is a selective inhibitor of thrombin. Upon binding to thrombin, hTM409-426 adopts a well-defined conformation-namely, a beta-turn followed by an antiparallel beta-sheet, similar to those found in all other EGF-like protein repeats (Hrabal et al., Protein Science, 1996, Vol. 5, 195-203). Here we demonstrate that, at pH 6.8 and at 25 degrees C, the hTM409-426 peptide in the free state is very flexible, but still populates a type II beta-turn over residues Pro410-Glu411-Gly412-Tyr413 and the clustering of some hydrophobic side chains, both of which are present in the thrombin-bound conformation. At a lower temperature of 5 degrees C, significant conformational shifts of the C alpha H proton resonances and extensive medium- and long-range NOEs are observed, indicating the presence of folded conformations with unique backbone-backbone and side-chain interactions. A comparison of the NOE patterns in the free state with transferred NOEs shows that the free-state folded and the thrombin-bound conformations of the hTM409-426 peptide are very similar, particularly over residues Pro410-Ile424. The folded conformation of hTM409-426 appears to be stabilized by two hydrophobic clusters, one formed by the side chains of residues Pro410, Tyr413, Leu415, and Phe419 and the Cys409-Cys421 disulfide bond, the second involving residues Ile414 and Ile424. These results indicate that the overall topology of the thrombin-bound conformation of the hTM409-426 peptide is prefolded in the free state and the primary sequence (including the disulfide bond) may be selective for an ensemble of conformations similar to that recognized by thrombin.

Magnetic Resonance Spectroscopy↗

PubMedDate not supplied

Mass spectrometry for the quantification of bioactive peptides in biological fluids.

The study of pharmacologically active peptides is central to the understanding of disease and development of novel therapies. It would be advantageous to monitor the fate of bioactive peptides in biological fluids and tissues following their in vivo administration (exogenous administration) or the modulation of endogenous factors (e.g., peptide hormones) affected by the administration of a pharmacological agent. Measurement of administered compounds (small molecules) in plasma is a mature field. However, measurement of pharmacologically active peptides presents particular problems for quantitative mass spectrometry, including challenges from selectivity and sensitivity perspectives. Current approaches towards peptide quantification in biological fluids include immunoassays and mass spectrometric techniques. Immunoassays, although sensitive, lack the necessary selectivity for distinction between peptide and metabolites. Modified molecules induced by metabolic transformations (e.g., N- or C-terminal truncation of the peptide) might not be differentiated by the antibody used in the assay, leading to cross-reactivity. However, although it is generally accepted that mass spectrometry is an ideal technique for the quantification of trace levels of analytes in biological fluids, immunological techniques are still characterized by better limits of peptide detection. In this review article, novel mass spectrometric approaches and strategies on peptide quantification will be described. The current capabilities and prospects for advances in this critical area of research will be examined.

Body Fluids↗

PubMed1999

The quest for novel bioactive peptides utilizing orphan seven-transmembrane-domain receptors.

Various sorts of bioactive molecules including hormones, neurotransmitters, and chemokines transmit signals into cells by binding to so-called seven-transmembrane-domain receptors (7TMRs). The recent progress in cDNA and genome DNA analyses has brought the discovery of numerous genes encoding ligand-unknown "orphan" 7TMRs. We have developed a strategy to identify the ligands of orphan 7TMRs by monitoring specific signal transductions induced in cells expressing orphan 7TMRs. Employing this method, we succeeded in identifying the natural ligands of the orphan 7TMRs, hGR3, and APJ. The ligand peptide identified for hGR3 was found to show a specific prolactin release promoting activity in rat anterior pituitary cells in in vitro culture and was therefore named "prolactin-releasing peptide." We named another novel bioactive peptide "apelin," for "APJ endogenous ligand." Although the biological functions of apelin are still under investigation, APJ reportedly acts as a coreceptor in the process of human immunodeficiency virus infection. We believe that the identification of orphan 7TMR ligands will provide clues to reveal the unknown regulatory mechanisms of various physiological phenomena and opportunities for novel drug discovery in the future.

Animals↗

PubMed2001

Evidence of secondary structure by high-resolution magic angle spinning NMR spectroscopy of a bioactive peptide bound to different solid supports.

The structure of the 19-amino acid peptide epitope, corresponding to the 141-159 sequence of capsid viral protein VP1 of foot-and-mouth disease virus (FMDV), bound to three different resins, namely, polystyrene-MBHA, PEGA, and POEPOP, has been determined by high-resolution magic angle spinning (HRMAS) NMR spectroscopy. A combination of homonuclear and heteronuclear bidimensional experiments was used for the complete peptide resonance assignment and the qualitative characterization of the peptide folding. The influence of the chemicophysical nature of the different polymers on the secondary structure of the covalently attached FMDV peptide was studied in detail. In the case of polystyrene-MBHA and polyacrylamide-PEGA resins, the analysis of the 2D spectra was hampered by missing signals and extensive overlaps, and only a propensity toward a peptide secondary structure could be derived from the assigned NOE correlations. When the FMDV peptide was linked to the polyoxyethylene-based POEPOP resin, it was found to adopt in dimethylformamide a helical conformation encompassing the C-terminal domain from residues 152 to 159. This conformation is very close to that of the free peptide previously analyzed in 2,2,2-trifluoroethanol. Our study clearly demonstrates that a regular helical structure can be adopted by a resin-bound bioactive peptide. Moreover, a change in the folding was observed when the same peptide-POEPOP conjugate was swollen in aqueous solution, displaying the same conformational features as the free peptide in water. The possibility of studying solid-supported ordered secondary structures by the HRMAS NMR technique in a wide range of solvents can be extended either to other biologically relevant peptides and proteins or to new synthetic oligomers.

Amino Acid Sequence↗