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1.
Acad Med ; 99(7): 764-770, 2024 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-38466613

RESUMEN

PURPOSE: Transition to residency (TTR) courses facilitate the medical student-residency transition and are an integral part of senior medical student training. The authors established a common set of skills for TTR courses, and an expected level of entrustment students should demonstrate in each skill on TTR course completion. METHOD: A modified Delphi approach was used with 3 survey iterations between 2020 and 2022 to establish skills to be included in a TTR course. Nine TTR experts suggested general candidate skills and conducted a literature search to ensure no vital skills were missed. A stakeholder panel was solicited from email lists of TTR educators, residency program directors, and residents at the panelists' institutions. Consensus was defined as more than 75% of participants selecting a positive inclusion response. An entrustment questionnaire asked panelists to assign a level of expected entrustment to each skill, with 1 indicating observation only and 6 indicating perform independently. RESULTS: The stakeholder panel initially consisted of 118 respondents with representation across educational contexts and clinical specialties. Response rates were 54% in iteration 2, 42% in iteration 3, and 33% on the entrustment questionnaire. After 3 iterations, 54 skills met consensus and were consolidated into 37 final skills categorized into 18 clinical skills (e.g., assessment and management of inpatient concerns), 14 communication skills (e.g., delivering serious news or having difficult conversations), 4 personal and professional skills (e.g., prioritization of clinical tasks), and 1 procedural skill (mask ventilation). Median entrustment levels were reported for all skills, with 19 skills having a level of expected entrustment of 4 (perform independently and have all findings double-checked). CONCLUSIONS: These consensus skills can serve as the foundation of a standardized national TTR curriculum framework. Entrustment guidance may help educational leaders optimize training and allocation of resources for TTR curriculum development and implementation.


Asunto(s)
Competencia Clínica , Consenso , Técnica Delphi , Internado y Residencia , Humanos , Competencia Clínica/estadística & datos numéricos , Competencia Clínica/normas , Encuestas y Cuestionarios , Curriculum , Estudiantes de Medicina/estadística & datos numéricos , Estudiantes de Medicina/psicología , Femenino , Masculino
2.
J Gen Intern Med ; 37(9): 2224-2229, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35710662

RESUMEN

INTRODUCTION: Clinical reasoning encompasses the process of data collection, synthesis, and interpretation to generate a working diagnosis and make management decisions. Situated cognition theory suggests that knowledge is relative to contextual factors, and clinical reasoning in urgent situations is framed by pressure of consequential, time-sensitive decision-making for diagnosis and management. These unique aspects of urgent clinical care may limit the effectiveness of traditional tools to assess, teach, and remediate clinical reasoning. METHODS: Using two validated frameworks, a multidisciplinary group of clinicians trained to remediate clinical reasoning and with experience in urgent clinical care encounters designed the novel Rapid Evaluation Assessment of Clinical Reasoning Tool (REACT). REACT is a behaviorally anchored assessment tool scoring five domains used to provide formative feedback to learners evaluating patients during urgent clinical situations. A pilot study was performed to assess fourth-year medical students during simulated urgent clinical scenarios. Learners were scored using REACT by a separate, multidisciplinary group of clinician educators with no additional training in the clinical reasoning process. REACT scores were analyzed for internal consistency across raters and observations. RESULTS: Overall internal consistency for the 41 patient simulations as measured by Cronbach's alpha was 0.86. A weighted kappa statistic was used to assess the overall score inter-rater reliability. Moderate reliability was observed at 0.56. DISCUSSION: To our knowledge, REACT is the first tool designed specifically for formative assessment of a learner's clinical reasoning performance during simulated urgent clinical situations. With evidence of reliability and content validity, this tool guides feedback to learners during high-risk urgent clinical scenarios, with the goal of reducing diagnostic and management errors to limit patient harm.


Asunto(s)
Razonamiento Clínico , Evaluación Educacional , Competencia Clínica , Humanos , Proyectos Piloto , Reproducibilidad de los Resultados
3.
Med Sci Educ ; 31(6): 2001-2005, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34956710

RESUMEN

BACKGROUND: Many medical schools offer a culminating internship readiness experience. Curricula focus on particular knowledge and skills critical to internship, such as answering urgent nursing pages. Studies have shown student performance improvement with mock paging education programs, but the role of feedback versus self-regulated practice has not been studied. DESIGN AND METHODS: The interprofessional mock paging program included 156 medical students enrolled in a 4th-year internship readiness course and 44 master's level direct entry nursing students. Medical students were randomized to receive verbal feedback immediately after each of the three phone calls (intervention group) or delayed written feedback (control group) after the third phone call only. Specialty-specific case scenarios were developed and a single checklist for all scenarios was developed using the communication tool ISBAR. Medical students and nursing students had separate training sessions before the pages commenced. The nursing students administered the phone calls and evaluated the medical students by ISBAR checklist. An interrater reliability measure was obtained with physician observation of a selection of phone calls. RESULTS: After adjusting for the case effects (different case scenarios for different specialties), students showed no statistically significant differences on checklist scores for case 1 (first case, F = 1.491, df = 1, p = .224), but did show statistically significant differences on checklist scores for case 3 (final case, F = 12.238, df = 1, p = .001). Strong interrater reliability was found between the faculty physician and observed nursing students (ICC = .89). CONCLUSIONS: Immediate feedback significantly improves student checklist scores with a mock paging program. This finding suggests that coaching with feedback may have advantages above self-regulated learning.

4.
Case Rep Cardiol ; 2012: 537169, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-24826260

RESUMEN

Transient left ventricular apical ballooning syndrome is characterized by transient akinesis of the left ventricular apex with basal wall hyperkinesis; this is also known as Takotsubo cardiomyopathy. There are three distinct contractile LV patterns described in the literature: apical, midventricular, and basal ballooning. The apical ballooning pattern is the most frequent pattern. We describe the case of a transient anterolateral left ventricular ballooning fulfilling the definition of Takotsubo cardiomyopathy except for the contractile LV pattern. The diagnosis was supported by cardiac magnetic resonance imaging and by the fact that the anterolateral ballooning resolved completely after 6 weeks.

5.
Biochem Biophys Res Commun ; 412(3): 407-12, 2011 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-21835166

RESUMEN

RNA editing by adenosine deamination, catalyzed by adenosine deaminases acting on RNA (ADAR), is a post-transcriptional modification that contributes to transcriptome and proteome diversity and is widespread in mammals. Here we administer a bioinformatics search strategy to the human and mouse genomes to explore the landscape of A-to-I RNA editing. In both organisms we find evidence for high excess of A/G-type discrepancies (inosine appears as a guanosine in cloned cDNA) at non-polymorphic, non-synonymous codon sites over other types of discrepancies, suggesting the existence of several thousand recoding editing sites in the human and mouse genomes. We experimentally validate recoding-type A-to-I RNA editing in a number of human genes with high scoring positions including the coatomer protein complex subunit alpha (COPA) as well as cyclin dependent kinase CDK13.


Asunto(s)
Adenina/metabolismo , Edición de ARN/genética , Animales , Secuencia de Bases , Genoma Humano , Genómica , Humanos , Inosina/metabolismo , Ratones , Transcriptoma
7.
J Pept Res ; 65(3): 364-74, 2005 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-15787967

RESUMEN

A novel type of water-soluble prodrugs of cyclosporine A (CsA) is described, featuring a modular system of an enzyme-cleavable group, a solubilizing moiety and a chemodegradable spacer attached to the hydroxyl function of (4R)-4-[(E)-2-butenyl]-4-,N-dimethyl-l-threonine (MeBmt)-1 of CsA. The chemical synthesis of these double prodrugs proceeds in high yield and purity and allows for a systematic study of the influence of the structural parameters upon physicochemical and pharmacological properties. The evaluation of the chemical and enzymatic stability results in differential values of the conversion rates (minutes to several hours) in support of an enzyme-triggered release of the parent drug as the rate-limiting step. In vitro studies show that the designed prodrug systems can be regarded as soft prodrugs in being devoid of cyclophiline A (CypA) binding and that complete conversion to the parent drug occurs in whole rat blood, setting the stage for therapeutic use.


Asunto(s)
Ciclosporina/química , Ciclosporina/farmacocinética , Inmunosupresores/química , Inmunosupresores/farmacocinética , Profármacos/síntesis química , Profármacos/metabolismo , Animales , Biotransformación , Profármacos/química , Ratas , Solubilidad , Agua/química
8.
Eur J Pharm Biopharm ; 59(1): 51-6, 2005 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-15567301

RESUMEN

The aim of this study was to evaluate the rate and mechanism of conversion of two water-soluble prodrugs of cyclosporine A (CsA) intended for topical delivery to the eye. The new molecules were designed according to the double prodrug concept: a solubilizing moiety was grafted onto CsA via an ester function, which could be hydrolysed via a two-step process (enzymatic and chemical). Prodrug solutions were prepared extemporaneously in an isotonic and neutral aqueous medium compatible with ophthalmic use. The rates of conversion into the parent molecule were determined by incubating the prodrugs in fresh rabbit or human tears or in a phosphate buffer solution (PBS) at pH 7.4. Both prodrugs were converted into CsA within the first minute in the presence of rabbit tears with rate constants of k=5.9x10(-3)min(-1) and k=3.8x10(-3)min(-1), respectively, for UNIL088 and UNIL089, whereas chemical conversion in PBS was negligible (k=0.5x10(-3)min(-1) for both molecules). Incubation of UNIL088 in human tears showed a significantly high conversion rate. It is concluded that the developed double prodrugs underwent a bioconversion in physiological media and thus represent promising candidates for topical delivery of CsA to the eye.


Asunto(s)
Ciclosporina/farmacocinética , Profármacos/farmacocinética , Lágrimas/metabolismo , Animales , Ciclosporina/química , Humanos , Profármacos/química , Conejos
9.
J Pept Res ; 63(2): 147-54, 2004 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-15009536

RESUMEN

The cyclic undecapeptide cyclosporin A (CsA) has a remarkable spectrum of diverse biological activities, including anti-inflammatory, antifungal, antiparasitic as well as immunosuppressive activities. However, the low water solubility of this drug is a serious problem causing undesirable pharmacological properties such as erratic oral absorption. In order to overcome this problem, the design and synthesis of water-soluble prodrugs of CsA are described. Using the OH-MeBmt-1-group as attachment site, we investigate dipeptide systems exhibiting differential tendencies for intramolecular cyclization [diketopiperazine (DKP) formation] for tailoring the chemoreversible release of the parent CsA. In modulating the chemical and structural features of the dipeptide esters (N-alkylation, side chains, C-terminal Pro), we find conversion rates at physiological conditions ranging from minutes to several days. Together with their thermodynamic stability in the solid state and strongly enhanced solubility in water, these chemoreversible CsA prodrugs represent versatile candidates for therapeutical use.


Asunto(s)
Ciclosporina/química , Profármacos/química , Profármacos/metabolismo , Estructura Molecular , Profármacos/síntesis química
10.
Onkologie ; 25(5): 406-11, 2002 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-12415193

RESUMEN

BACKGROUND: Nicotine is the main culprit for dependence on tobacco-containing products, which in turn are a major etiologic factor for cardiovascular diseases and cancer. This publication describes a vaccine, which elicits antibodies against nicotine. The antibodies in the blood stream intercept the nicotine molecule on its way to its receptors and greatly diminish the nicotine influx to the brain shortly after smoking. METHODS: The nicotine molecule is chemically linked to cholera toxin B as a carrier protein in order to induce antibodies. The potential to elicit antibodies after subcutaneous as well as intranasal immunization is evaluated. In order to simulate realistic conditions, nicotine pumps delivering the nicotine equivalent of 5 packages of cigarettes for 4 weeks are implanted into the mice 1 week prior to vaccination. The protective effect of the vaccine is measured 5 weeks after vaccination by comparing the influx of radiolabeled nicotine in the brains of vaccinated and non-vaccinated animals 5 min after challenge with the nicotine equivalent of 2 cigarettes. RESULTS: The polyclonal antibodies induced by the vaccine show a mean avidity of 1.8 x 10(7) l/Mol. Subcutaneous immunization elicits high antibody levels of the IgG class, and significant IgA antibody levels in the saliva of vaccinated mice can be found after intranasal vaccination. The protective effect also in the animals with implanted nicotine pumps is significant: less than 10% of radiolabeled nicotine found in the brains of non-vaccinated animals can be found in the brains of vaccinated animals. CONCLUSIONS: These data provide credible evidence that a vaccine can break the vicious circle between smoking and instant gratification by intercepting the nicotine molecule. Astonishingly, there is no sign of exhaustion of specific antibodies even under extreme conditions, which makes it highly unlikely that a smoker can overcome the protective effect of the vaccine by smoking more. Finally, the high titers of specific antibodies after 1 year let us hope that booster vaccinations are probably only necessary in intervals of years.


Asunto(s)
Proteínas Portadoras/inmunología , Toxina del Cólera/inmunología , Nicotina/inmunología , Cese del Hábito de Fumar/métodos , Prevención del Hábito de Fumar , Tabaquismo/prevención & control , Vacunas Sintéticas/inmunología , Administración Intranasal , Animales , Encéfalo/inmunología , Femenino , Inmunoglobulina A/sangre , Inmunoglobulina G/sangre , Bombas de Infusión , Ratones , Ratones Endogámicos BALB C , Fumar/inmunología , Tabaquismo/inmunología
11.
J Med Chem ; 44(23): 3896-903, 2001 Nov 08.
Artículo en Inglés | MEDLINE | ID: mdl-11689075

RESUMEN

Analogues of the opioid peptides [D-Phe(3)]morphiceptin (H-Tyr-Pro-D-Phe-Pro-NH(2)) and endomorphin-2 (H-Tyr-Pro-Phe-Phe-NH(2)) containing the pseudoproline (Psi Pro) (4R)-thiazolidine-4-carboxylic acid (Cys[Psi(R1,R2)pro]) or (4S)-oxazolidine-4-carboxylic acid (Ser[Psi(R1,R2)pro]) in place of Pro(2) were synthesized. The pseudoproline ring in these compounds was either unsubstituted (R(1), R(2) = H) or dimethylated (R(1), R(2) = CH(3)) at the 2-C position. 2-C-dimethylated pseudoprolines are known to be quantitative or nearly quantitative inducers of the cis conformation around the Xaa(i-1)-Xaa(i)[Psi(CH(3),CH)(3)pro)] imide bond. All dihydropseudoproline-containing analogues (R(1), R(2) = H) showed good mu opioid agonist potency in the guinea pig ileum (GPI) assay, high mu receptor binding affinity in the rat brain membrane binding assay, and, like their parent peptides, excellent mu receptor binding selectivity. (1)H NMR spectroscopic analysis of the Cys[Psi(H,H)pro](2)- and Ser[Psi(H,H)pro](2)-containing analogues in DMSO-d(6) revealed that they existed in a conformational equilibrium around the Tyr-Xaa[Psi(H,H)pro] peptide bond with cis/trans ratios of 40:60 and 45:55, respectively. The dimethylated thiazolidine- and oxazolidine-containing [D-Phe(3)]morphiceptin- and endomorphin-2 analogues (R(1), R(2) = CH(3)) all retained full mu agonist potency in the GPI assay and displayed mu receptor binding affinities in the nanomolar range and high mu receptor selectivity. As expected, no conformers of the latter analogues with a trans conformation around the Tyr-Xaa[Psi(CH(3),CH(3)pro)] imide bond were detected by (1)H NMR spectral analysis, indicating that in these compounds the cis conformation is highly predominant (>98%). These results represent the most direct evidence obtained so far to indicate that morphiceptin and endomorphin-2 have the cis conformation around the Tyr-Pro peptide bond in their bioactive conformations.


Asunto(s)
Endorfinas/síntesis química , Oligopéptidos/síntesis química , Oxazoles/síntesis química , Prolina/análogos & derivados , Prolina/síntesis química , Receptores Opioides/metabolismo , Tiazoles/síntesis química , Animales , Encéfalo/metabolismo , Endorfinas/química , Endorfinas/metabolismo , Cobayas , Íleon/efectos de los fármacos , Técnicas In Vitro , Espectroscopía de Resonancia Magnética , Masculino , Ratones , Contracción Muscular/efectos de los fármacos , Músculo Liso/efectos de los fármacos , Oligopéptidos/química , Oligopéptidos/metabolismo , Oxazoles/química , Oxazoles/metabolismo , Prolina/química , Prolina/metabolismo , Conformación Proteica , Ensayo de Unión Radioligante , Ratas , Receptores Opioides delta/metabolismo , Receptores Opioides mu/metabolismo , Tiazoles/química , Tiazoles/metabolismo , Conducto Deferente/efectos de los fármacos
12.
J Pept Sci ; 7(3): 146-51, 2001 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-11297350

RESUMEN

An experimental system is described, permitting a detailed and systematic analysis of the factors governing self-assembly of amphipathic helices, e.g. to a four-helical bundle, a subject of major relevance for tertiary structure formation, protein folding and design. Following the Template Assembled Synthetic Proteins (TASP) approach, helices of different packing potential are competitively assembled in solution with a preformed two-helix TASP molecule, and after equilibration are covalently attached ('template trapping') via chemoselective thioether formation. The quantitative analysis of the individual TASP molecules by high performance liquid chromatography (HPLC) and electrospray mass spectrometry (ES-MS) allows the delineation of the role of complementary packing in helix bundle formation. The procedure established represents a general tool for the experimental verification of modern concepts in molecular recognition.


Asunto(s)
Pliegue de Proteína , Estructura Secundaria de Proteína , Proteínas/síntesis química , Secuencia de Aminoácidos , Fenómenos Químicos , Química Física , Cromatografía Líquida de Alta Presión , Dicroismo Circular , Técnicas Químicas Combinatorias , Modelos Químicos , Modelos Moleculares , Datos de Secuencia Molecular , Unión Proteica , Estructura Terciaria de Proteína , Proteínas/química , Espectrometría de Masa por Ionización de Electrospray
13.
Acta Biochim Pol ; 48(4): 1105-7, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-11995973

RESUMEN

A novel methodology for the reversible competitive condensation of peptide loops to chemoreactive topological templates is presented.


Asunto(s)
Bioquímica/métodos , Péptidos/química , Proteínas/química , Unión Competitiva , Cromatografía Líquida de Alta Presión , Ligandos , Modelos Químicos , Estructura Terciaria de Proteína
14.
Chembiochem ; 2(6): 432-7, 2001 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-11828474

RESUMEN

The structural prototype of a new generation of regioselectively addressable functionalized templates (RAFTs) for use in protein de novo design has been synthesized and crystallized. The structure of the aromatically substituted cyclodecapeptide was determined by X-ray diffraction; it consists of an antiparallel beta sheet spanned by heterochirally induced type IIprime prime or minute beta turns, similar to that observed in gramicidin S. The three-dimensional structure of the artificial template was also examined by an NMR spectroscopic analysis in solution and shown to be compatible with a beta-sheet plane suitable for accommodating secondary functional peptide fragments for the synthesis of template-assembled synthetic proteins (TASPs).


Asunto(s)
Péptidos Cíclicos/química , Cristalización , Cristalografía por Rayos X , Espectroscopía de Resonancia Magnética/métodos , Estructura Molecular , Péptidos Cíclicos/síntesis química , Conformación Proteica , Estructura Terciaria de Proteína
15.
J Mol Graph Model ; 18(3): 290-8, 309-10, 2000 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-11021545

RESUMEN

Experience has shown that protein redesigns (using the backbone from a known protein structure) are far more likely to produce well-ordered, native-like structures than are true de novo designs. Therefore, to design a four-helix bundle made of identical short helices, we here proceed by an extensive redesign of the ROP protein. A fully symmetrical SymROP sequence derived from ROP was chosen by modeling ideal-geometry side chains, including hydrogens, while maintaining the "goodness-of-fit" of side-chain packing by calculating all-atom contact surfaces with the Reduce and Probe programs. To estimate the probable extent of backbone movement and side-chain mobility, restrained molecular dynamics simulations were compared for candidate sequences and controls, including substitution of Abu for all or half the core Ala residues. The resulting 17-residue designed sequence is 41% identical to the relevant regions in ROP. SymROP is intended for construction by the Template Assembled Synthetic Proteins approach, to control the bundle topology, to use short helices, and to allow blocked termini and unnatural amino acids. ROP protein has been a valuable system for studying helical protein structure because of its simplicity and regularity within a structure large enough to have a real hydrophobic core. The SymROP design carries that simplicity and regularity even further.


Asunto(s)
Proteínas Bacterianas/química , Simulación por Computador , Modelos Químicos , Ingeniería de Proteínas/métodos , Proteínas de Unión al ARN/química , Secuencia de Aminoácidos , Aminoácidos/química , Gráficos por Computador , Datos de Secuencia Molecular , Movimiento (Física) , Estructura Secundaria de Proteína
17.
Chemistry ; 6(23): 4358-63, 2000 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-11140965

RESUMEN

The insertion of acetals that exhibit variable structural features into complex peptides such as cyclosporin C (CsC) results in oxazolidine derivatives (pseudoprolines, psiPro) of tailored physico-chemical and biological properties. N,O-Acetalation of the 2-threonine hydroxyl group and the preceding amide nitrogen of CsC is achieved by treating the molecule with a number of both arylated and non-arylated dimethyl acetals. The psiPro-containing CsC derivatives exhibit enhanced conformational backbone rigidity, as suggested by analytical HPLC, NMR spectroscopy and by kinetic measurements on binding with their receptor protein cyclophilin A (CypA) that were not time-dependent. IC50 values for calf-thymus CypA were obtained by kinetic evaluation of its cis-->trans isomerase activity. The choice of the para-substituted aryl dimethyl acetals allows the inhibitory properties of the corresponding derivatives to be modulated to either prodrugs or moderately strongly binding cyclosporin C derivatives.


Asunto(s)
Ciclofilina A/antagonistas & inhibidores , Ciclosporinas/química , Ciclosporinas/síntesis química , Inmunosupresores/síntesis química , Prolina/análogos & derivados , Animales , Bovinos , Diseño de Fármacos , Inmunosupresores/química , Indicadores y Reactivos , Modelos Moleculares , Conformación Molecular , Estructura Molecular , Timo/enzimología
18.
J Pept Res ; 54(3): 185-94, 1999 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-10517155

RESUMEN

The creation of native-like macromolecules in copying nature's way represents a fascinating challenge in protein chemistry today. In the absence of a detailed knowledge of the complex folding pathway the ultimate goal in protein de novo design, the construction of artificial proteins with predetermined three-dimensional structure and tailor-made functions based on a defined, generally valid set of rules, appears to be still out of reach. With progress in synthesis strategies and biostructural characterization methods, topological templates have become a versatile tool for inducing and stabilizing secondary and tertiary structures, such as protein loops, beta-turns, alpha-helices, beta-sheets and a variety of folding motifs. In this article, we extend the concept of template-assembled synthetic proteins for the construction of protein-like topologies with multiply bridged, oligocyclic chain architectures termed locked-in tertiary folds that exhibit unique physicochemical and folding properties because of the highly confined conformational space. Furthermore, we show that some fundamental questions in protein assembly can be approached applying the template concept. Using covalent template trapping of self-associated peptide assemblies in aqueous solution the structural and physical forces guiding protein folding, supramolecular assembly and molecular recognition processes can be studied on a molecular level.


Asunto(s)
Ingeniería de Proteínas/métodos , Estructura Secundaria de Proteína , Moldes Genéticos , Cromatografía Líquida de Alta Presión , Dicroismo Circular , Espectrometría de Masas , Modelos Moleculares , Modelos Estructurales , Biosíntesis de Proteínas , Estructura Terciaria de Proteína , Proteínas/síntesis química , Proteínas/química , Relación Estructura-Actividad , Dedos de Zinc
19.
J Pept Sci ; 5(7): 313-22, 1999 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-10442767

RESUMEN

The design and synthesis of cyclic mimetics of VCAM-1 protein that reproduce the integrin-binding domain are presented. The unprotected peptide precursor 37-43, Thr-Gln-Ile-Asp-Ser-Pro-Leu, was grafted onto functional templates of type naphthalene, biphenyl and benzyl through the chemoselective formation of C- and N-terminal oximes resulting in a mixture of four isomeric forms due to syn-anti isomerism of the oxime bonds. Some isomers could be monitored by HPLC and identified by NMR. The molecule containing a naphthalene-derived template was found to inhibit the VCAM-1/VLA-4 interaction more efficiently than previously reported for sulfur-bridged cyclic peptides containing similar sequences. The finding confirms the importance of incorporating conformational constraints between the terminal ends of the peptide loop 37-43 in the design of synthetic inhibitors of the VCAM-1/integrin interaction.


Asunto(s)
Imitación Molecular , Molécula 1 de Adhesión Celular Vascular/química , Secuencia de Aminoácidos , Animales , Línea Celular , Cromatografía Líquida de Alta Presión , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Ratones , Oligopéptidos/química , Oligopéptidos/metabolismo , Unión Proteica , Conformación Proteica , Molécula 1 de Adhesión Celular Vascular/metabolismo
20.
Biopolymers ; 50(4): 361-72, 1999 Oct 05.
Artículo en Inglés | MEDLINE | ID: mdl-10423545

RESUMEN

Extensive conformational analysis of a series of beta-alkyl substituted cyclopeptides-cyclo(Pro(1)-Xaa(2)-Nle(3)-Ala(4)-Nle(5)-Pro(6)-Xaa(7)- Nle(8)-Ala(9)-Nle(10)) and cyclo[Pro(1)-Xaa(2)-Nle(3)-(Cys(4)- Nle(5)-Pro(6)-Xaa(7)-Nle(8)-Cys(9))-Nle(10)] as well as their corresponding unsubstituted core structures cyclo(Pro(1)-Xaa(2)-Ala(3)-Ala(4)-Ala(5)-Pro(6)-Xaa(7)-Ala(8)-Ala(9)- Ala(10)) and cyclo(Pro(1)-Xaa(2)-Ala(3)-Cys(4)- Ala(5)-Pro(6)-Xaa(7)-Ala(8)-Cys(9)-Ala(10)) has been performed employing both the ECEPP/2 and the MAB force fields (Xaa = Gly, L-Ala, D-Ala, Aib, and D-Pro). Results show that (a) possible three-dimensional structures of the cyclo(Pro(1)-Gly(2)-Lys(3)-Ala(4)-Lys(5)-Pro(6)-Gly(7)-Lys(8)-Ala(9)- Lys(10)) molecule are not limited to a single extended "rectangular" conformation with all Lys side chains oriented at the same side of the molecule; (b) conformational equilibrium in monocyclic analogues obtained by replacements of conformationally flexible Gly residues for L-Ala, D-Ala, Aib, or D-Pro is not significantly shifted towards the target "rectangular" conformational type; and (c) introduction of disulfide bridges between positions 4 and 9 is a very powerful way to stabilize the target conformations in the resulting bicyclic molecules. These findings form the basis for further design of rigidified regioselectively addressable functionalized templates with many application areas ranging from biostructural to diagnostic purposes.


Asunto(s)
Modelos Moleculares , Conformación Proteica , Secuencia de Aminoácidos , Datos de Secuencia Molecular , Moldes Genéticos
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