Ligand Noninnocence in ß-Diketiminate and ß-Diketimine Copper Complexes.

Metal-ligand cooperative systems have a long precedent in catalysis, with the classification depending on the site of substrate bond cleavage and formation and on redox state changes. Recently, our group reported the participation of a ß-diketiminate ligand in chemical bonding to heterocumulenes such as CO2 and CS2 by tricopper complexes, leading to cooperative catalysis. Herein, we report the reactivity of these copper clusters, [Cu3EL]- (E = S, Se; L = tris(ß-diketiminate) cyclophane ligand), toward other electrophiles, viz. alkyl halides and Brønsted acids. We identified a family of ligand-functionalized complexes, Cu3EL (R) (R = primary alkyls), and a series of disubstituted products, Cu3EL (R)2, through single-crystal X-ray diffraction, mass spectrometry, and infrared and UV-visible spectroscopy. As part of mechanistic studies on these alkylation reactions, we evaluated the acid-base reactivity of these complexes and the influence of the backbone substitution on the reduction potential. Implications of these findings for ligand noninnocence and the relevance of the metal core as a cofactor for the ligand's reactivity are discussed.

Metal-Tuned Ligand Reactivity Enables CX2 (X = O, S) Homocoupling with Spectator Cu Centers.

Ligand non-innocence is ubiquitous in catalysis with ligands in synthetic complexes contributing as electron reservoirs or co-sites for substrate activation. The latter chemical non-innocence is manifested in H+ storage or relay at sites beyond the metal primary coordination sphere. Reaction of a competent CO2-to-oxalate reduction catalyst, namely, [K(THF)3](Cu3SL), where L3- is a tris(ß-diketiminate) cyclophane, with CS2 affords tetrathiooxalate at long reaction times or at high CS2 concentrations, where otherwise an equilibrium is established between the starting species and a complex-CS2 adduct in which the CS2 is bound to the C atom on the ligand backbone. X-ray diffraction analysis of this adduct reveals no apparent metal participation, suggesting an entirely ligand-based reaction controlled by the charge state of the cluster. Thermodynamic parameters for the formation of the aforementioned Cligand-CS2 bond were experimentally determined, and trends with cation Lewis acidity were studied, where more acidic cations shift the equilibrium toward the adduct. Relevance of such an adduct in the reduction of CO2 to oxalate by this complex is supported by DFT studies, similar effects of countercation Lewis acidity on product formation, and the homocoupled heterocumulene product speciation as determined by isotopic labeling studies. Taken together, this system extends chemical non-innocence beyond H+ to effect catalytic transformations involving C-C bond formation and represents the rarest example of metal-ligand cooperativity, that is, spectator metal ion(s) and the ligand as the reaction center.

Metal Site-Specific Electrostatic Field Effects on a Tricopper(I) Cluster Probed by Resonant Diffraction Anomalous Fine Structure (DAFS).

Studies of multinuclear metal complexes are greatly enhanced by resonant diffraction measurements, which probe X-ray absorption profiles of crystallographically independent metal sites within a cluster. In particular, X-ray diffraction anomalous fine structure (DAFS) analysis provides data that can be interpreted akin to site-specific XANES, allowing for differences in metal K-edge resonances to be deconvoluted even for different metal sites within a homometallic system. Despite the prevalence of Cu-containing clusters in biology and energy science, DAFS has yet to be used to analyze multicopper complexes of any type until now. Here, we report an evaluation of trends using a series of strategically chosen Cu(I) and Cu(II) complexes to determine how energy dependencies of anomalous scattering factors are impacted by coordination geometry, ligand shell, cluster nuclearity, and oxidation state. This calibration data is used to analyze a formally tricopper(I) complex that was found by DAFS to be site-differentiated due to the unsymmetrical influence on different Cu sites of the electrostatic field from a proximal K+ cation.

Undervalued professionals: placement of nutritionist in the Ecuadorian health system.

BACKGROUND: Currently, many public health issues are directly related to malnutrition, and are made worse by social inequities. Nutrition professionals must be a key player in improving epidemiological aspects of nutrition-related diseases and must be part of clinical teams to control nutritional concerns. OBJECTIVE: To identify and analyze the nutritionists´ employment situation in Ecuador and areas of work covered and determine if type of university has an impact over work situation. METHODOLOGY: A cross-sectional study was conducted, approved by the ethics committee of Universidad San Francisco de Quito. It included 442 nutritionists in Ecuador who graduated in 13 universities (5 private (PR) and 8 public (PU)) between 2008 and 2019. It implied an online survey that questioned their satisfaction with their education and current work situation. All the statistical analyses were performed using R version 4.0.3, two-sided weighted chi-square test was performed to estimate the difference between public and private university graduates, IC 95%, p between 0.01 and 0.05. RESULTS: 38,6% of participants are unemployed, 68,28% private university graduates (PR) are currently employed and 58.87% work as nutritionists, compared to 56,86% from a public university (PU) currently working and 44.69% working in the field. 76% have reported being unemployed at some point in their careers, being difficulty finding jobs the main reason. Regarding the professional field, most professionals have their own business, and the less common area of work was public and community nutrition. One third of the participants had another paid activity. The main salary is 800USD per month and graduated from PR perceived better salaries than from PU. CONCLUSION: There is a lack of job opportunities for Ecuadorian nutritionists despite the high demand in every level of the health system. Most have been unemployed at some point in their careers due to difficulties finding jobs. There is a minimum nutrition staff working in community and public health nutrition.

Nonlinear N - Compartments model of respiratory mechanics considering viscoelasticity, inertia and surface tension properties.

Respiratory biomechanics constitutes an important topic in clinical practice. Different strategies like mathematical models have been implemented to understand and replicate scenarios allowing deeper analysis. In this paper, a nonlinear N - compartments model is presented, allowing to represent the lung in a heterogeneous way. It considers the resistance of each generation of the airway and each alveolar compartment characterized independently. Includes properties of nonlinear elastance, viscoelasticity, inertia, and surface tension. In this work, to show the functionality of the model, a simulation of four alveolar units coupled to the airway model is presented using pressure as input signal simulating mechanical ventilation. However, the model can be used to simulate any desired number of alveolar units. Values at airway output were compared to the linear model, obtaining a correlation close to 1. Also, was compared to a physical test lung using Hamilton - S1 mechanical ventilator obtaining a positive correlation. The model makes it possible to evaluate the effects of different properties during spontaneous respiration or mechanical ventilation, both at the airway opening and alveolar. These properties include viscoelasticity, surface tension, inertia, among others.

Computational model of trachea-alveoli gas movement during spontaneous breathing.

A computational model of the transport of gases involved in spontaneous breathing, from the trachea inlet to the alveoli was developed for healthy patients. Convective and diffusive transport mechanisms were considered simultaneously, using a diffusion coefficient (D) that has considered the four main species of gases present in the exchange carried out by the human lung, nitrogen (N2), oxygen (O2), carbon dioxide (CO2) and water vapor (H2O). A Matlab® script was programmed to simulate the trachea-alveolus gas exchange model under three respiratory frequencies: 12, 24 and 40 breaths per minute (BPM), each with three diaphragmatic movements of 2 cm, 4 cm, and 6 cm. During the simulations, the CO2 inlet concentrations in the alveoli and the O2 concentration at the inlet of the trachea were kept constant. A simplified but stable model of mass transport between the trachea and alveoli was obtained, allowing the concentrations to be determined dynamically at the selected test points in the airway.

Prevention of preterm delivery with vaginal progesterone in women with preterm labour (4P): randomised double-blind placebo-controlled trial.

OBJECTIVE: To evaluate the effectiveness of 200 mg of daily vaginal natural progesterone to prevent preterm birth in women with preterm labour. DESIGN: Multicentre, randomised, double-blind, placebo-controlled trial. SETTING: Twenty-nine centres in Switzerland and Argentina. POPULATION: A total of 385 women with preterm labour (24(0/7) to 33(6/7) weeks of gestation) treated with acute tocolysis. METHODS: Participants were randomly allocated to either 200 mg daily of self-administered vaginal progesterone or placebo within 48 hours of starting acute tocolysis. MAIN OUTCOME MEASURES: Primary outcome was delivery before 37 weeks of gestation. Secondary outcomes were delivery before 32 and 34 weeks, adverse effects, duration of tocolysis, re-admissions for preterm labour, length of hospital stay, and neonatal morbidity and mortality. The study was ended prematurely based on results of the intermediate analysis. RESULTS: Preterm birth occurred in 42.5% of women in the progesterone group versus 35.5% in the placebo group (relative risk [RR] 1.2; 95% confidence interval [95% CI] 0.93-1.5). Delivery at <32 and <34 weeks did not differ between the two groups (12.9 versus 9.7%; [RR 1.3; 95% CI 0.7-2.5] and 19.7 versus 12.9% [RR 1.5; 95% CI 0.9-2.4], respectively). The duration of tocolysis, hospitalisation, and recurrence of preterm labour were comparable between groups. Neonatal morbidity occurred in 44 (22.8%) cases on progesterone versus 35 (18.8%) cases on placebo (RR: 1.2; 95% CI 0.82-1.8), whereas there were 4 (2%) neonatal deaths in each study group. CONCLUSION: There is no evidence that the daily administration of 200 mg vaginal progesterone decreases preterm birth or improves neonatal outcome in women with preterm labour.

Alteraciones morfo-cardiovasculares producidas por bacterias periodontopatógenas en modelo murino / Morphological and cardiovascular alterations produced by periodontopathic bacteria in a murine model

Diferentes autores han descrito a la enfermedad periodontal como un factor de riesgo de ateroesclerosis. Este estudio tuvo como objetivo determinar la posible relación entre las bacterias periodontopatógenas y alteraciones cardiovasculares en modelos murinos con ingesta hiperlipídica. Se utilizaron 30 ratas Wistar divididas en un grupo control (n=5) y tres grupos experimentales (n=15): Grupo I (n=5): dieta normal e infectados; Grupo II (n=5): dieta hiperlipídica y sin infectar y Grupo III (n=5): dieta hiperlipídica e infectados. La infección del surco gingival se logró previa sedación a través de hilos de sutura contaminados, colocados durante 6 días consecutivos, con Pophyromonas gingivalis (P. gingivalis) (5x10a-4 UFC) y Agregatibacter actinomycetemcomitans (A. actinomycetemcomitans) (5x10-4 UFC) obtnidas de muestras de pacientes con periodontitis crónica. A los 30 días posinfección se fijaron muestras de corazón y arteria aorta para su procesamiento. En el grupo control no se encontraron alteraciones. En el grupo I se observó en el endocardio valvular abundante exudado fibrinoleucocitario y focos hemorrágicos. En el miocardio, neovascularización y sufusiones hemorrágicos y en la pared de vasos arteriales, engrosamiento intimal. En el grupo II se observaron depósitos lipídicos en el interior de las células endoteliales, estrías grasas y pequeños ateromas. El grupo III mostró en un 100 por ciento de los casos, placas ateromatosas bien detalladas con abundante depósito de colesterol, calcificaciones, hemorragias y neovascularización. La suma de estos factores de riesgo: dieta hiperlipídica e infección con bacterias periodontopatógenas, potenciarían la expresión de alteraciones cardíacas y coronarias, incrementando la formación de ateromas

Alteraciones morfo-cardiovasculares producidas por bacterias periodontopatógenas en modelo murino / Morphological and cardiovascular alterations produced by periodontopathic bacteria in a murine model

Diferentes autores han descrito a la enfermedad periodontal como un factor de riesgo de ateroesclerosis. Este estudio tuvo como objetivo determinar la posible relación entre las bacterias periodontopatógenas y alteraciones cardiovasculares en modelos murinos con ingesta hiperlipídica. Se utilizaron 30 ratas Wistar divididas en un grupo control (n=5) y tres grupos experimentales (n=15): Grupo I (n=5): dieta normal e infectados; Grupo II (n=5): dieta hiperlipídica y sin infectar y Grupo III (n=5): dieta hiperlipídica e infectados. La infección del surco gingival se logró previa sedación a través de hilos de sutura contaminados, colocados durante 6 días consecutivos, con Pophyromonas gingivalis (P. gingivalis) (5x10a-4 UFC) y Agregatibacter actinomycetemcomitans (A. actinomycetemcomitans) (5x10-4 UFC) obtnidas de muestras de pacientes con periodontitis crónica. A los 30 días posinfección se fijaron muestras de corazón y arteria aorta para su procesamiento. En el grupo control no se encontraron alteraciones. En el grupo I se observó en el endocardio valvular abundante exudado fibrinoleucocitario y focos hemorrágicos. En el miocardio, neovascularización y sufusiones hemorrágicos y en la pared de vasos arteriales, engrosamiento intimal. En el grupo II se observaron depósitos lipídicos en el interior de las células endoteliales, estrías grasas y pequeños ateromas. El grupo III mostró en un 100 por ciento de los casos, placas ateromatosas bien detalladas con abundante depósito de colesterol, calcificaciones, hemorragias y neovascularización. La suma de estos factores de riesgo: dieta hiperlipídica e infección con bacterias periodontopatógenas, potenciarían la expresión de alteraciones cardíacas y coronarias, incrementando la formación de ateromas (AU)

Development of a multiplex PCR assay to detect gastroenteric pathogens in the feces of Mexican children.

Acute gastroenteritis (AGE) is a major cause of childhood morbidity and mortality worldwide; the etiology of AGE includes viruses, bacteria, and parasites. A multiplex PCR assay to simultaneously identify human Astrovirus (HAstV), Calicivirus (HuCVs), Entamoeba histolytica (E. histolytica), and enteroinvasive Escherichia coli (EIEC) in stool samples is described. A total of 103 samples were individually analyzed by ELISA (enzyme-linked immunosorbent assays) and RT-PCR/PCR. HAstV and HuCVs were detected in four out of 103 samples (3.8 %) by RT-PCR, but ELISAs found only one sample as positive for HuCVs (2.5 %). E. histolytica was identified in two out of 19 samples (10.5 %) and EIEC in 13 out of 20 samples (70 %) by PCR, and all PCR products were sequenced to verify their identities. Our multiplex PCR results demonstrate the simultaneous amplification of different pathogens such as HAstV, EIEC, and E. histolytica in the same reaction, though the HuCVs signal was weak in every replicate. Regardless, this multiplex PCR protocol represents a novel tool for the identification of distinct pathogens and may provide support for the diagnosis of AGE in children.

La microalbuminuria como factor pronóstico en un grupo de pacientes hipertensos de una entidad de primer nivel de atención de Manizales (Colombia), 2010 / The microalbuminuria as factor prognosis in a group of hypertense patients of an entity of 1º level of attention of Manizales (Colombia), 2010

Objetivos: Determinar el valor de la microalbuminuria en un grupo de pacientes hipertensos. Materiales y métodos: Se estudiaron pacientes inscritos en el programa de vigilancia y control de la hipertensión arterial de ASSBASALUD ESE (Manizales, Colombia), clasificados como de riesgo bajo y moderado. Se diseñó un estudio transversal para el análisis de los factores de riesgo asociados: dislipidemia, obesidad, diabetes mellitus, infarto agudo de miocardio relacionándolos con los niveles de microalbuminuria encontrados en la investigación. Resultados: El estudio se hizo con 86 pacientes hipertensos (76,7% mujeres). En 16,7% (Ic95%: 9,4-26,45) de ellos los niveles de microalbuninuria se encontraron alterados. Las cifras halladas estuvieron entre 95,1mg/dl, valor máximo, y una cifra mínima de 0,1mg/ dl. El valor promedio fue de 11,77mg/dl. En 34,9% de los pacientes se registraron antecedentes patológicos, en 74,2% el antecedente fue dislipidemia y obesidad en el 32% de los casos. 64% de los pacientes tenían antecedentes familiares patológicos, hipertensión arterial en el 30,9% e infarto del miocardio en el 16,4%. Se encontró relación significativa entre microalbuminuria y el valor de índice de masa corporal (p=0,028). Conclusiones: La frecuencia de microalbuminuria positiva relacionada con dislipidemia fue similar a la obtenida en otros estudios. Se encontró una elevada prevalencia de microalbuminuria alterada en pacientes con dislipidemia. La frecuencia de microalbuminuria anormal encontrada en la población estudiada indica presencia de riesgo cardiovascular.

Objective: To determine the value of microalbuminuria in a group of hypertensive patients. Materials and methods: Patients subscribed to the arterial-hypertension monitor and control program of ASSBASALUD E.S.E. (Manizales, Caldas) where studied. The patients were classified as low and moderate risk. And a cross-sectional study was designed for the analysis of the associated risk factors: dyslipidemia, obesity, diabetes Mellitus, acute myocardial infarction relating these factors with the microalbuminuria values found during the investigation. Results: The study was made with 86 hypertensive patients (76.7% women). In 16,7% the levels of microalbuminuria where abnormal. The found values had as maximum 95,1 mg/dl, and minimum 0,1 mg/dl with an average of 13,58 mg/dl. 34.9% of the patients registered pathological antecedents, in 74.2% the antecedent was dislipidemia and in 32% obesity. 64% of the patients had pathological family antecedents, 30% arterial hypertension and 16.4% myocardial infarction. A significant relation was found between the MA and the body mass index (p=0.028). Conclusions: The frequency of microalbuminuria related to dyslipidemia was similar to that obtained in other studies. A high prevalence was found of altered microalbuminuria in patients with dyslipidemia. The frequency of abnormal microalbuminuria found in the studied population indicates the presence of cardiovascular risk factor.

Peptides derived from Mycobacterium tuberculosis Rv2301 protein are involved in invasion to human epithelial cells and macrophages.

The specific function of putative cut2 protein (or CFP25), encoded by the Rv2301 gene from Mycobacterium tuberculosis H37Rv, has not been identified yet. The aim of this study was to assess some of CFP25 characteristics and its possible biological role in Mycobacterium tuberculosis H37Rv invasion process to target cells. Molecular assays indicated that the gene encoding Rv2301 is present and transcribed in M. tuberculosis complex strains. The presence of Rv2301 protein over the bacilli surface was confirmed by Western blot and immunoelectron microscopy analyses, using goats sera inoculated with synthetic peptides derived from Rv2301 protein. Receptor-ligand binding assays with carcinomic human alveolar basal epithelial cells (A549) and macrophages derived from human histolytic lymphoma monocytes (U937) allowed us to identify five high activity binding peptides (HABPs) in both cell lines, and two additional HABPs only in A549 cells. U937 HABPs binding interactions were characterized by saturation assays, finding dissociation constants (Kd) within the nanomolar range and positive cooperativity (nH>1). Inhibition assays were performed to assess the possible biological role of Rv2301 identified HABPs, finding that some of them were able to inhibit invasion at a 5 µM concentration, compared with the cytochalasin control. On the other hand, HABPs, and especially HABP 36507 located at the N-terminus of the protein, facilitated the internalization of fluorescent latex beads into A549 cells. These findings are of vital importance for the rational selection of Rv2301 HABPs, to be included as components of an antituberculosis vaccine.

Post-translational regulation of rotavirus protein NSP1 expression in mammalian cells.

The nonstructural rotavirus protein NSP1 binds specifically to viral mRNAs and to interferon regulatory factor 3 (IRF3), inducing IRF3 degradation through a proteasome-dependent pathway. By using a vaccinia virus expression system in mammalian cells, we found that the yield of NSP1 was 8- and 13-fold lower than the viral proteins VP2 or NSP3, respectively; while in the presence of proteasome inhibitors such difference could be reduced to 2- to 2.5-fold, respectively. The susceptibility of NSP1 to proteasome degradation was fully reversed in a dose-dependent manner by transfection with the full complement of 11 molecules of translation-competent rotavirus mRNAs, but this effect was abrogated by the protein synthesis inhibitor cycloheximide. These results demonstrate that NSP1 is degraded through a proteasome-dependent pathway, and viral proteins, alone or in combination with viral mRNAs, interfere with such degradation.

Phylogenetic Relationships Among Selected Heteroderoidea Based on 18S and ITS Ribosomal DNA.

In a study of relationships among selected cyst-forming and noncyst-forming species of Heteroderoidea, combined sequences comprised of DNA from part of the conserved 18S ribosomal RNA gene (rDNA) plus the complete ITS rDNA segment were more similar to analyses based on the ITS data alone than to analyses based on the 18S data alone. One of the two noncyst-forming species, Ekphymatodera thomasoni, grouped with cyst-forming species of Heteroderoidea. Bilobodera flexa, also a noncyst-forming species, was separated from all the other taxa by a long branch. Afenestrata koreana, with a weakly sclerotized cyst, grouped closely with H. bifenestra. These observations suggest that phylogenetic analyses using molecular data may aid in our understanding of the evolution of cyst formation in nematodes, including the possibility of secondary loss. The usefulness of molecular phylogenetic analyses in nematodes may depend more on the particular selection of taxa than on mere addition of data from additional genes.

Protein products of the open reading frames encoding nonstructural proteins of human astrovirus serotype 8.

Human astroviruses have a positive-strand RNA genome, which contains three open reading frames (ORF1a, ORF1b, and ORF2). The genomic RNA is translated into two nonstructural polyproteins, nsp1a and nsp1ab, that contain sequences derived from ORF1a and from both ORF1a and ORF1b, respectively. Proteins nsp1a and nsp1ab are thought to be proteolytically processed to yield the viral proteins implicated in the replication of the virus genome; however, the intermediate and final products of this processing have been poorly characterized. To identify the cleavage products of the nonstructural polyproteins of a human astrovirus serotype 8 strain, antisera to selected recombinant proteins were produced and were used to analyze the viral proteins synthesized in astrovirus-infected Caco-2 cells and in cells transfected with recombinant plasmids expressing the ORF1a and ORF1b polyproteins. Pulse-chase experiments identified proteins of approximately 145, 88, 85, and 75 kDa as cleavage intermediates during the polyprotein processing. In addition, these experiments and kinetic analysis of the synthesis of the viral proteins identified polypeptides of 57, 20, and 19 kDa, as well as two products of around 27 kDa, as final cleavage products, with the 57-kDa polypeptide most probably being the virus RNA polymerase and the two approximately 27-kDa products being the viral protease. Based on the differential reactivities of the astrovirus proteins with the various antisera used, the individual polypeptides detected were mapped to the virus ORF1a and ORF1b regions.

Plasmodium falciparum EBA-140 kDa protein peptides that bind to human red blood cells.

The erythrocyte-binding antigen 140 (EBA140) sequence was chemically synthesized in 61 20-mer sequential peptides covering the entire 3D7 protein strain, each of which was tested in erythrocyte-binding assays. Peptides 26135, 26144, 26147, 26160, 26170 and 26177 presented high erythrocyte-binding activity, with affinity constants ranging from 350 to 750 nM. Critical erythrocyte-binding residues were determined by competition-binding assays with glycine analogous peptides. Cross-linking assays with SDS-PAGE from high erythrocyte membrane protein binding peptides showed that all these peptides bound specifically to 25, 52 and 75 kDa erythrocyte membrane proteins. The nature of these receptor sites was studied in peptide-binding assays using enzyme-treated erythrocytes, showing that these protein receptors are susceptible to structural changes provoked by enzyme treatment (neuraminidase, trypsin or chymotrypsin). Inhibition invasion assays in 'in vitro' cultures showed that all specific high binding sequences were able to inhibit invasion by 11-69% at 200 microM concentration.

Phylogenetic relationships of a distinct species of globodera from portugal and two punctodera species.

Evolutionary relationships based on ribosomal DNA (rDNA) sequence data for a previously unknown species of Globodera from Portugal, Punctodera chalcoensis from Mexico, and P. punctata from Estonia, plus previously published sequences, support the following relationships: (((Cactodera weissi, G. artemisiae, C. milleri), ((G. sp. Bouro, G. sp. Canha, G. sp. Ladoeiro), ((G. pallida, G. rostochiensis), (P. chalcoensis, P. punctata)))), Heterodera avenae). Globodera sp. from Portugal, which can be confused with potato cyst nematodes by phytosanitary services when the identification is based only on morphological characters, is clearly different based on our molecular data. In addition, the rDNA data show the Globodera sp. to be only distantly related to other European Globodera species that parasitize Asteraceae. Punctodera chalcoensis and P. punctata form a sister clade to the G. pallida + G. rostochiensis clade.

Plasmodium falciparum: binding studies of peptide derived from the sporozoite surface protein 2 to Hep G2 cells.

Plasmodium falciparum sporozoite surface protein 2 (Pf SSP2), also called thrombospondin related anonymous protein (TRAP), is involved in the process of sporozoite invasion of hepatocytes. Pf SSP2/TRAP possesses two different adhesion domains sharing sequences and structural homology with von Willebrand factor A-domains and human repeat I thrombospondin (TSP). Pf SSP2/TRAP has also been implicated in sporozoite mobility and in mosquito salivary gland invasion processes. We tested 15-mer long synthetic peptides having five overlapping residues covering the complete protein Pf SSP2 sequence in binding assays to Hep G2 cells. In these 57 peptides, 21 high-activity binding peptides (HABPs) were identified; five were in the adhesion domains already described and 16 were in two regions toward the protein's carboxy and middle terminal part. Six HABPs showed conserved amino acid sequences: 3243 (21FLVNGRDVQNNIVDE35), 3279 (201FLVGCHPSDGKCNLY215), 3287 (241TASCGVWDEWSPCSV255), 3289 (251SPCSVTCGKGTRSRK265), 3327 (441ERKQSDPQSQDNNGNY455) and 3329 (451DNNGNRHVPNSEDREY465). The HABPs show saturable binding and dissociation constants between 140 and 900 nm with 40 000-855 000 binding sites per cell. The 3279 (201FLVGCHPSDGKCNLY215), 3323 (421NDKSDRYIPYSPLSP435) and 3331 (461SEDRETRPHGRNNENY475) HABPs have B epitopes in their sequences; these have previously been recognized by antibodies partially inhibiting hepatocyte invasion and development of the hepatic state. The 3287 (241TASCGVWDEWSPCSV255) and 3289 (251SPCSVTCGKGTRSRK265) HABPs share common sequences with the Pf SSP2/TRAP region II plus, which is present in a great number of adhesion proteins. Based on this information, six new peptides covering the high binding regions identified previously were synthesized and, using a competition assay, the amino acid involved in the binding were determined.