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At least 703 records · Page 39Linked to original sources

PubMed2005

[Expression and effect of hCGRP recombinant adeno-associated virus in primary cultured corporal cavernosum smooth muscle cells of the rat in vitro].

OBJECTIVE: To observe the expression and effect of human calcitonin gene-related peptide (hCGRP) gene mediated by recombinant adeno-associated virus (rAAV) in primary cultured corporal cavernosum smooth muscle cells of the rat and explore the possibility of using CGRP gene for gene therapy in erectile dysfunction. METHODS: The primary cultured corporal cavernosum smooth muscle cells of the rat were randomly divided into 4 groups and infected with recombinant virus VssHGCMV-hCGRP, VssHGCMV, VssC-MV-GFP and the untreated, respectively. CGRP-like immunoreactivity was measured by protein dot blot assay in the 24 h-culture medium, and intracellular cAMP and cGMP levels in the cultured cells were also determined using radioimmunoassay to ascertain bioactivity of transduced CGRP. RESULTS: The exogenous gene was transferred into primary corporal cavernosum smooth muscle cells by VssHGCMV-hCGRP infection and efficiently expressed. Compared with the control group, intracellular cAMP level in the cell infected by VssHGCMV-hCGRP was significantly increased (48.7 +/- 1.1 nmol/L vs 7.8 +/- 1.4 nmol/L, P < 0.01), whereas cGMP level remained unchanged in two groups, and CGRP-like immunoreactivity was also detected in the culture medium infected by VssHGCMV- hCGRP. CONCLUSION: The system of secretory expressing bioactive peptide rAAV mediated gene transfer may be used to express efficiently exogenous gene in corporal cavernosum smooth muscle cells and affect cAMP level in the corporal cavernosum smooth muscle cells of the rat.

Animals↗

PubMed2000

Evaluating the efficacy of mucoactive aerosol therapy.

The aerosol route is attractive for the delivery of mucoactive medications. Mucoactive medications include mucolytics, which depolymerize polymers of mucin (classic mucolytics) or DNA/actin (peptide mucolytics), mucokinetic agents, which increase cough clearance, mucoregulatory medications, which decrease abnormal mucus secretion, and expectorants and ion channel modifiers. Despite the widespread use of these medications, there are few well conducted studies and thus few data clearly supporting (or failing to support) their use. This will change as our understanding of mucociliary physiology and pharmacology increases and as well designed and well powered clinical trials are conducted with appropriate outcome measurements. Effective mucoactive therapy should make a profound impact on the care of patients with chronic bronchitis, asthma, cystic fibrosis, and inflammatory airways disease, and will be essential for the effective delivery of gene therapy vectors and bioactive peptides to the airway epithelium.

Administration, Inhalation↗

PubMed2003

Dipeptidyl-peptidase IV from bench to bedside: an update on structural properties, functions, and clinical aspects of the enzyme DPP IV.

Dipeptidyl-peptidase IV/CD26 (DPP IV) is a cell-surface protease belonging to the prolyloligopeptidase family. It selectively removes the N-terminal dipeptide from peptides with proline or alanine in the second position. Apart from its catalytic activity, it interacts with several proteins, for instance, adenosine deaminase, the HIV gp120 protein, fibronectin, collagen, the chemokine receptor CXCR4, and the tyrosine phosphatase CD45. DPP IV is expressed on a specific set of T lymphocytes, where it is up-regulated after activation. It is also expressed in a variety of tissues, primarily on endothelial and epithelial cells. A soluble form is present in plasma and other body fluids. DPP IV has been proposed as a diagnostic or prognostic marker for various tumors, hematological malignancies, immunological, inflammatory, psychoneuroendocrine disorders, and viral infections. DPP IV truncates many bioactive peptides of medical importance. It plays a role in glucose homeostasis through proteolytic inactivation of the incretins. DPP IV inhibitors improve glucose tolerance and pancreatic islet cell function in animal models of type 2 diabetes and in diabetic patients. The role of DPP IV/ CD26 within the immune system is a combination of its exopeptidase activity and its interactions with different molecules. This enables DPP IV/CD26 to serve as a co-stimulatory molecule to influence T cell activity and to modulate chemotaxis. DPP IV is also implicated in HIV-1 entry, malignant transformation, and tumor invasion.

Amino Acid Sequence↗

PubMed1998

Production of active chimeric pediocin AcH in Escherichia coli in the absence of processing and secretion genes from the Pediococcus pap operon.

Minimum requirements have been determined for synthesis and secretion of the Pediococcus antimicrobial peptide, pediocin AcH, in Escherichia coli. The functional mature domain of pediocin AcH (Lys+1 to Cys+44) is targeted into the E. coli sec machinery and secreted to the periplasm in active form when fused in frame to the COOH terminus of the secretory protein maltose-binding protein (MBP). The PapC-PapD specialized secretion machinery is not required for secretion of the MBP-pediocin AcH chimeric protein, indicating that in Pediococcus, PapC and PapD probably are required for recognition and processing of the leader peptide rather than for translocation of the mature pediocin AcH domain across the cytoplasmic membrane. The chimeric protein displays bactericidal activity, suggesting that the NH2 terminus of pediocin AcH does not span the phospholipid bilayer in the membrane-interactive form of the molecule. However, the conserved Lys(+1)-Tyr-Tyr-Gly-Asn-Gly-Val(+7)-sequence at the NH2 terminus is important because deletion of this sequence abolishes activity. The secreted chimeric protein is released into the culture medium when expressed in a periplasmic leaky E. coli host. The MBP fusion-periplasmic leaky expression system should be generally advantageous for production and screening of the activity of bioactive peptides.

ATP-Binding Cassette Transporters↗

PubMed2006

The prognostic value of big endothelin-1 in more than 2,300 patients with heart failure enrolled in the Valsartan Heart Failure Trial (Val-HeFT).

BACKGROUND: Endothelin is elevated in heart failure and contributes to neurohormonal activation, hemodynamic deterioration, and cardiovascular remodeling. Here, we examined its prognostic value in a large population of patients with chronic heart failure. METHODS AND RESULTS: Big endothelin-1 (Big ET-1) and 4 other neurohormones were measured at study entry in 2359 patients enrolled in the Valsartan Heart Failure Trial (Val-HeFT) and their concentrations related to outcome over a median follow-up of 23 months. Baseline concentration of Big ET-1 (median 0.80 pmol/L) was proportional to severity of disease (New York Heart Association class, left ventricular structure and function). High circulating concentrations of brain natriuretic peptide (BNP), creatinine and bilirubin, advanced New York Heart Association class, elevated body mass index, and the presence of atrial fibrillation were independently associated to higher concentrations of Big ET-1. Big ET-1 (ranking second just behind BNP among neurohormonal factors) was an independent predictor of outcome defined as all-cause mortality (hazard ratio 1.49, 95% CI 1.20-1.84, P = .0003) or the combined endpoint of mortality and morbidity (hazard ratio 1.43, 95% CI 1.20-1.69, P < .0001) and provided incremental prognostic value compared with BNP. CONCLUSIONS: In a large population of patients with symptomatic heart failure, the circulating concentration of Big ET-1, a precursor of the paracrine and bioactive peptide ET-1, was an independent marker of mortality and morbidity. In this setting, BNP remained the strongest neurohormonal prognostic factor.

Aged↗

PubMed2004

The cDNA for leucomyosuppressin in Blattella germanica and molecular evolution of insect myosuppressins.

Myosuppressins are a group of 10-residues FMRFamide-related peptides reported in Dictyoptera, Orthoptera, Lepidoptera and Diptera. Myosuppressins inhibit visceral muscle contractions and, in the cockroach Blattella germanica, inhibit food intake. In B. germanica, the cDNA of leucomyosuppressin (LMS) has been cloned and sequenced. The deduced precursor is 96 amino acids long and contains a single copy of LMS. Brain mRNA levels remain constant during the first reproductive cycle of adult females, whereas those in the gut show a slight decline during the time of maximal food intake. Comparison of myosuppressin precursors of different species reveals that all have the same organization. Phylogenetic analysis suggests that the precursor experienced an accelerated evolution in Lepidoptera and Diptera with respect to Dictyoptera, whereas only Lepidoptera has radical changes in the bioactive peptide.

Amino Acid Sequence↗

PubMed2004

A novel protein expression strategy using recombinant bovine respiratory syncytial virus (BRSV): modifications of the peptide sequence between the two furin cleavage sites of the BRSV fusion protein yield secreted proteins, but affect processing and function of the BRSV fusion protein.

The bovine respiratory syncytial virus (BRSV) fusion (F) protein is cleaved at two furin cleavage sites, which results in generation of the disulfide-linked F(1) and F(2) subunits and release of an intervening peptide of 27 aa (pep27). A series of mutated open reading frames encoding F proteins that lacked the entire pep27, that contained an arbitrarily chosen 23 aa sequence instead of pep27 or in which pep27 was replaced by the amino acid sequences for the bovine cytokines interleukin 2 (boIL2), interleukin 4 (boIL4) or gamma interferon (boIFN-gamma) was constructed. Transient expression experiments revealed that the sequence of the intervening peptide influenced intracellular transport, maturation of the F protein and F-mediated syncytium formation. Expression of boIL2, boIL4 or boIFN-gamma in place of pep27 resulted in secretion of the cytokines into the culture medium. All mutated F proteins except the boIFN-gamma-containing variant could be expressed by and were functional for recombinant BRSV. Characterization of the cell culture properties of the recombinants demonstrated that the amino acid sequence between the two furin cleavage sites affected entry into target cells, direct spreading of virions from cell to cell and virus growth. Secretion of boIL2 and boIL4 into the medium of cells infected with the respective recombinants demonstrated that the F protein can be used to express secreted heterologous bioactive peptides or (glyco)proteins, which might be of interest for the development of novel RSV vaccines.

Amino Acid Sequence↗

PubMed1994

Measurement of gut hormone gene expression: mRNA and peptides.

During the past decade numerous methods for measurement of mRNA and peptides have been developed. Since the expression cascade from DNA to protein is regulated at all levels, the methods should be carefully designed to accomplish the purpose of the analysis. Regulation of the nuclear processing, the translational activity and the decay of a particular mRNA changes the proportionality between transcriptional activity and production of prepropeptide. Moreover, the post-translational maturation of the pro-hormones may be attenuated. Detection of mRNA is valuable and feasible because it is easy to generate cDNA probes for most hormones, and because mRNA demonstration unequivocally indicates the cellular site of gene expression. The deduction of preprohormone structures has also made it possible to improve the versatility of radioimmunoassays (RIA). Monospecific antibodies and pure tracers have allowed the development of sequence-specific RIA libraries for bioactive peptides and their precursors. Recently we have introduced a simple processing-independent analysis (PIA) for clinical use, since the post-translational maturation of gut peptides may be changed in gastrointestinal diseases. So far PIA has improved the diagnostic sensitivity for gut hormone tumours.

Animals↗

PubMed2006

Alpha-selenoconotoxins, a new class of potent alpha7 neuronal nicotinic receptor antagonists.

Disulfide bonds are important structural motifs that play an essential role in maintaining the conformational stability of many bioactive peptides. Of particular importance are the conotoxins, which selectively target a wide range of ion channels that are implicated in numerous disease states. Despite the enormous potential of conotoxins as therapeutics, their multiple disulfide bond frameworks are inherently unstable under reducing conditions. Reduction or scrambling by thiol-containing molecules such as glutathione or serum albumin in intracellular or extracellular environments such as blood plasma can decrease their effectiveness as drugs. To address this issue, we describe a new class of selenoconotoxins where cysteine residues are replaced by selenocysteine to form isosteric and nonreducible diselenide bonds. Three isoforms of alpha-conotoxin ImI were synthesized by t-butoxycarbonyl chemistry with systematic replacement of one ([Sec(2,8)]ImI or [Sec(3,12)]ImI), or both ([Sec(2,3,8,12)]ImI) disulfide bonds with a diselenide bond. Each analogue demonstrated remarkable stability to reduction or scrambling under a range of chemical and biological reducing conditions. Three-dimensional structural characterization by NMR and CD spectroscopy indicates conformational preferences that are very similar to those of native ImI, suggesting fully isomorphic structures. Additionally, full bioactivity was retained at the alpha7 nicotinic acetylcholine receptor, with each selenoanalogue exhibiting a dose-response curve that overlaps with wild-type ImI, thus further supporting an isomorphic structure. These results demonstrate that selenoconotoxins can be used as highly stable scaffolds for the design of new drugs.

Amino Acid Sequence↗

PubMed1998

Induction of multiple pituitary adenylate cyclase activating polypeptide (PACAP) transcripts through alternative cleavage and polyadenylation of proPACAP precursor mRNA.

Many regulated events guide neuropeptide biosynthesis, processing, and secretion. For PACAP peptides, these events have not been well examined. In our studies of PACAP expression in sympathetic neurons, we discovered that neuronal depolarization not only increased the levels of the 2.2 kb form of proPACAP mRNA identified in neuronal tissues, but also induced a novel 0.9 kb PACAP transcript, which appeared similar in size to a form present in testes. Using reverse-transcription PCR and 3' RACE studies, we demonstrated that the 0.9 kb PACAP mRNA in depolarized SCG neurons was not identical to the testicular PACAP mRNA, but represented shortened, more stable, forms of the 2.2 kb transcript resulting from alternative upstream polyadenylation site usage. These results demonstrate that post-transcriptional mechanisms play important roles in determining cellular PACAP levels and provide several important insights. For example, alternative upstream polyadenylation can elicit a major influence on the amount of bioactive peptide that can by synthesized, since short 3' UTR transcripts are usually more stable due to elimination of destabilizing elements present in the longer messages. In cells such as testicular germ cells, which have restricted transcriptional periods, stable mRNAs allow longer translational events and extended periods of peptide production. The neuronal PACAP system adopts a similar post-transcriptional strategy following neuronal depolarization, and although the roles of PACAP remain unclear, this suggests important roles for PACAP peptides during increased neuronal activity. Additionally, unlike alternative polyadenylation described for many genes, alternative site usage in the proPACAP transcript does not result from alternative splicing. The mechanism of alternative site usage may be related to changes in the expression and binding of polyadenylation factors to the short and long 3' UTR proPACAP sites leading to production of more stable transcripts and increased PACAP precursor biosynthesis. The implications of increased PACAP production following altered neurophysiological states and the mechanisms underlying alternative polyadenylation site choice are important considerations for future inquiries.

Alternative Splicing↗

PubMed1995

The preferred solid-state conformation of (alpha Me)Trp peptides.

The two Z-L-Ala-DL-(alpha Me)Trp-NH2 diastereomeric dipeptides were synthesized from (Z-L-Ala)2(O) and H-DL-(alpha Me)Trp-NH2. The latter racemate, prepared by phase-transfer catalyzed alkylation of the N alpha-benzylidene derivative of alanine amide followed by acidic hydrolysis of the resulting Schiff base, was characterized by X-ray diffraction. The molecular and crystal structure of Z-L-Ala-L-(alpha Me)Trp-NH2, separated from its diastereomer by silica-gel column chromatography, was determined by X-ray diffraction analysis. Both independent molecules in the asymmetric unit of the dipeptide adopt a type-II beta-bend conformation. However, only the more regularly folded conformation of molecule B is stabilized by a 1<--4 C = O...H--N intramolecular H bond. The present results indicate that: (i) the C alpha-methylated (alpha Me)Trp residue is a strong beta-bend and helix former, and (ii) the relationship between (alpha Me)Trp chirality and helix screw sense tends to be opposite to that of protein amino acids. The implications for the use of the (alpha Me)Trp residue in designing conformationally restricted analogs of bioactive peptides are briefly discussed.

Amino Acid Sequence↗

PubMed2001

Downregulation of microglial activation by apolipoprotein E and apoE-mimetic peptides.

Apolipoprotein E plays an important role in recovery from acute brain injury and risk of developing Alzheimer's disease. We demonstrate that biologically relevant concentrations of apoE suppress microglial activation and release of TNFalpha and NO in a dose-dependent fashion. Peptides derived from the apoE receptor-binding region mimic the effects of the intact protein, whereas deletion of apoE residues 146-149 abolishes peptide bioactivity. These results are consistent with the hypothesis that apoE modulates microglial function by binding specific cell surface receptors and that the immunomodulatory effects of apoE in the central nervous system may account for its role in acute and chronic neurological disease.

Animals↗

PubMed1993

Angiotensin II responsiveness of rat paraventricular and subfornical organ neurons in vitro.

The responsiveness of neurons in the hypothalamic paraventricular nucleus to angiotensin II was investigated using extracellular single unit recording techniques in rat brain slices. Bath application of angiotensin II at a concentration of 3 x 10(-7) M for 2-5 min resulted in excitatory responses in 50.4% of 141 paraventricular cells tested. The mean increase in firing rate was 2.12 +/- 0.20 (mean +/- S.E.M.) spikes/s, which represents a mean increase in activity of 149.8 +/- 16.5%. Angiotensin II-sensitive neurons usually displayed irregular, phasic, or very slow spontaneous activity, with the majority of these neurons located in the magnocellular region. Under physiological blockade of synaptic transmission with low Ca2+/high Mg2+ medium, neuronal responses to this peptide remained in 12 (92.3%) of 13 cells tested. Application of three successive doses of angiotensin II ranging from 3 x 10(-9)-3 x 10(-7) M showed that neuronal responses were dose-dependent with an estimated threshold of 10(-8) M. In comparison with angiotensin III, angiotensin II not only stimulated more paraventricular cells, but usually induced larger excitatory responses. Angiotensin II subtype 1 receptor antagonist losartan completely blocked angiotensin II responsiveness in each of 14 paraventricular cells tested whereas PD 123319, an angiotensin II subtype 2 receptor antagonist, exhibited a partial inhibitory effect in about one half of another 13 cells. In addition, single unit in vitro subfornical organ recordings demonstrate that angiotensin II evokes greater excitatory responses than in the paraventricular nucleus and that these effects are abolished by losartan application. These results support the hypothesis that within both the paraventricular nucleus and subfornical organ angiotensin II is a bioactive peptide which modulates neuronal activity and thus may exert significant control over neuroendocrine and autonomic functions.

Action Potentials↗

PubMed1989

Substrate specificity and inhibitors of a capillary injury-related protease from sheep lung lymph.

A serine protease (Mr 70,000 to 75,000) appearing in sheep lung lymph after capillary damage induced by Escherichia coli endotoxin, oleic acid, or air emboli, was studied for its specificity toward a series of synthetic peptide and thioester substrates containing an Arg residue in the P1 position. High specificity constants (kcat/Km) were generally obtained with substrates having two or more basic amino acid residues, and with those having a Gln residues in the P2 position. Secondary enzyme-substrate interactions at sites more removed from the scissile bond are of importance, since a few peptides with two basic residues were hydrolyzed slowly, and the site of cleavage of natural peptides was influenced by the amino acid sequence beyond the immediate vicinity of the hydrolyzed bond. The properties of the enzyme and its pattern of specificity distinguish it from enzymes of the clotting cascade, from components of the complement system, and from lung and skin tryptase. The enzyme was inactivated by p-amidinophenylmethanesulfonyl fluoride and by a series of mechanism-based isocoumarin derivatives, the most potent inhibitor being 4-chloro-7-guanidino-3-(2-phenylethoxy)isocoumarin. Enzyme solutions inactivated by reaction with isocoumarin inhibitors could be completely reactivated after 30 h by treatment with hydroxylamine at neutral pH. Formation of a stable sheep lymph acyl enzyme--in contrast to thrombin and other trypsin-like enzymes--is not followed by alkylation of an active site nucleophile that leads to irreversible enzyme inactivation. The high activity toward substrates with two basic residues suggests that the enzyme may potentially function in processing of precursors of bioactive peptides.

Animals↗

PubMed1993

Solute adsorption on polymer-coated fused-silica capillary electrophoresis columns using selected protein and peptide standards.

Three series of basic proteins and peptides were selected for use in studying the adsorption behavior of fused-silica capillary electrophoresis columns. A comparative study of untreated and treated fused-silica columns was done. The polymers used as coating materials ranged from very hydrophobic to very hydrophilic. The average efficiency of weakly hydrophilic Ucon-coated capillaries for basic proteins was over 1 million theoretical plates at a buffer pH of 4.8. For this coating, it was found that the maximum column efficiency was obtained at a film thickness of approximately 100 nm. It was easily seen that both ionic and hydrophobic interaction forces can play important roles in protein adsorption onto the capillary walls. Furthermore, strongly hydrophilic polymer coatings may possibly lead to hydrogen-bonding interactions, which decrease column efficiency. Studies have been conducted using two series of polypeptides with varying chain lengths. One series was used to study the effect of polypeptide chain length on retention behavior. Efficient separations of bioactive peptide drugs on Ucon-coated columns were achieved. The results indicate that high efficiency and resolution of basic peptides tested can be realized on columns modified with weakly hydrophilic polymers at a pH value of about 5.

Adsorption↗

PubMedDate not supplied

Partial characterization of IR-alpha-MSH peptides found in melanoma tumors.

Our previous work indicated that IR-alpha-MSH (immunoreactive alpha-melanocyte-stimulating hormone) plasma levels are three times as high in melanoma patients with progressing disease than in disease-free patients, and that the melanoma tumor itself may be the source of IR-alpha-MSH. Further identification of the material in tumor extracts has been carried out in this study, and the results presented here show that the immunoreactivity is associated with a major fraction of about 16 kDa and another of 5-9 kDa. Significant amounts of the immunoreactive material were also found in human melanoma cells but not in culture supernatants. The presence of this material may be related to the melanogenic status of the tumor cells. We have estimated the intracellular IR-alpha-MSH to be within a 0.4 to 2.3 nM range in melanoma tumor cells. We have investigated the melanogenic effect of the IR-alpha-MSH material and its relationship to alpha-MSH. Purified extracts both from metastases and cultured cells were found to promote frog skin darkening as well as tyrosinase activity in Cloudman S91 melanoma cells. The IR material could also displace labeled alpha-MSH from its binding sites in human melanoma cells. Our data clearly indicate that melanoma cells engage in an autocrine production of alpha-MSH-like bioactive peptides by melanoma cells, of larger mol.wt., which are able to bind to MSH receptors. These peptides may be involved in the regulation of melanogenesis and possibly in the growth and proliferation of melanoma cells by an autocrine/paracrine mechanism.

Adult↗

PubMed2006

Proneurotensin 1-117, a stable neurotensin precursor fragment identified in human circulation.

Proneurotensin/neuromedin N (pro NT/NMN) is the common precursor of two biologically active peptides, neurotensin (NT) and neuromedin N (NMN). We have established antibodies against peptide sequences of the NT/NMN precursor and developed a sandwich immunoassay for the detection of pro NT/NMN immunoreactivity in human circulation. Endogenous pro NT/NMN immunoreactivity was enriched by affinity chromatography using antibodies against two different pro NT/NMN epitopes, and further purified by reversed phase HPLC. Mass spectrometry analysis revealed pro NT/NMN 1-117 as major pro NT/NMN immunoreactivity in human circulation. Pro NT/NMN 1-117 is detectable in serum from healthy individuals (n = 124; median 338.9 pmol/L). As known for NT, the release of pro NT/NMN 1-117 from the intestine into the circulation is stimulated by ingestion of an ordinary meal. Investigation of the pro NT/NMN 1-117 in vitro stability in human serum and plasma revealed that this molecule is stable for at least 48 h at room temperature. Since pro NT/NMN 1-117 is theoretically produced during precursor processing in stoichiometric amounts relative to NT and NMN, it could be a surrogate marker for the release of these bioactive peptides.

Amino Acid Sequence↗

PubMed1991

Peptides from chiral C alpha,alpha-disubstituted glycines. Crystallographic characterization of conformation of C alpha-methyl, C alpha-isopropylglycine [(alpha Me)Val] in simple derivatives and model peptides.

The molecular and crystal structures of one derivative and three model peptides (to the pentapeptide level) of the chiral C alpha,alpha-disubstituted glycine C alpha-methyl, C alpha-isopropylglycine [(alpha Me)Val] have been determined by X-ray diffraction. The derivative is mClAc-L-(alpha Me)Val-OH, and the peptides are Z-L-(alpha Me)Val-(L-Ala)2-OMe monohydrate, Z-Aib-L-(alpha Me)Val-(Aib)2-OtBu, and Ac-(Aib)2-L-(alpha Me)Val-(Aib)2OtBu acetonitrile solvate. The tripeptide adopts a type-I beta-turn conformation stabilized by a 1----4N--H...O = C intramolecular H-bond. The tetra- and pentapeptides are folded in regular right-handed 3(10)-helices. All four L-(alpha Me)Val residues prefer phi, psi angles in the right-handed helical region of the conformational map. The results indicate that: (i) the (alpha Me)Val residue is a strong type-I/III beta-turn and helix former, and (ii) the relationship between (alpha Me)Val chirality and helix screw sense is the same as that of C alpha-monosubstituted protein amino-acids. The implications for the use of the (alpha Me)Val residue in designing conformationally constrained analogues of bioactive peptides are briefly discussed.

Amino Acid Sequence↗