RESUMEN
PURPOSE: This study investigated metabolic benefits of protein hydrolysates from the macroalgae Palmaria palmata, previously shown to inhibit dipeptidylpeptidase-4 (DPP-4) activity in vitro. METHODS: Previously, Alcalase/Flavourzyme-produced P. palmata protein hydrolysate (PPPH) improved glycaemia and insulin production in streptozotocin-induced diabetic mice. Here the PPPH, was compared to alternative Alcalase, bromelain and Promod-derived hydrolysates and an unhydrolysed control. All PPPH's underwent simulated gastrointestinal digestion (SGID) to establish oral bioavailability. PPPH's and their SGID counterparts were tested in pancreatic, clonal BRIN-BD11 cells to assess their insulinotropic effect and associated intracellular mechanisms. PPPH actions on the incretin effect were assessed via measurement of DPP-4 activity, coupled with GLP-1 and GIP release from GLUTag and STC-1 cells, respectively. Acute in vivo effects of Alcalase/Flavourzyme PPPH administration on glucose tolerance and satiety were assessed in overnight-fasted mice. RESULTS: PPPH's (0.02-2.5 mg/ml) elicited varying insulinotropic effects (p < 0.05-0.001). SGID of the unhydrolysed protein control, bromelain and Promod PPPH's retained, or improved, bioactivity regarding insulin secretion, DPP-4 inhibition and GIP release. Insulinotropic effects were retained for all SGID-hydrolysates at higher PPPH concentrations. DPP-4 inhibitory effects were confirmed for all PPPH's and SGID counterparts (p < 0.05-0.001). PPPH's were shown to directly influence the incretin effect via upregulated GLP-1 and GIP (p < 0.01-0.001) secretion in vitro, largely retained after SGID. Alcalase/Flavourzyme PPPH produced the greatest elevation in cAMP (p < 0.001, 1.7-fold), which was fully retained post-SGID. This hydrolysate elicited elevations in intracellular calcium (p < 0.01) and membrane potential (p < 0.001). In acute in vivo settings, Alcalase/Flavourzyme PPPH improved glucose tolerance (p < 0.01-0.001) and satiety (p < 0.05-0.001). CONCLUSION: Bioavailable PPPH peptides may be useful for the management of T2DM and obesity.
Asunto(s)
Diabetes Mellitus Experimental , Péptido 1 Similar al Glucagón , Animales , Glucemia , Polipéptido Inhibidor Gástrico , Incretinas , Insulina/metabolismo , Ratones , Hidrolisados de Proteína , Regulación hacia ArribaRESUMEN
Wheat gluten, a Pro-rich dietary protein, was investigated for its potential to produce dipeptidyl peptidase IV (DPP-IV) inhibitory peptides during enzymatic hydrolysis with Debitrase HYW20. Nine gluten hydrolysates (H1-H9) were generated using a 2 factor × 3 level design of experiments (DOE) including the incubation temperature (40, 50 and 60 °C) and the enzyme: substrate ratio (E : S, 0.5, 1.0 and 1.5% (w/w)). Their DPP-IV half maximal inhibitory concentration (IC50) ranged from 0.24 ± 0.02 (H9) to 0.66 ± 0.06 mg mL-1 (H2A and H7) and their degree of hydrolysis (DH) from 31.7 ± 0.9 (H7) to 62.2 ± 3.0% (H6). Gluten and H9, the most potent DPP-IV inhibitory hydrolysate, were subjected to simulated gastrointestinal digestion (SGID), yielding Gluten_CorPP and H9_CorPP, respectively. H9_CorPP had a higher DPP-IV inhibitory potency than Gluten_CorPP (i.e., DPP-IV IC50 values of 0.33 ± 0.03 vs. 1.45 ± 0.26 mg mL-1, respectively). H9 and H9_CorPP both contained relatively potent DPP-IV inhibitory peptides such as Val-Pro-Leu, Trp-Leu and Trp-Pro which were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS). In addition, several sequences possessing features of DPP-IV inhibitory peptides, mostly consisting of a penultimate or C-terminal Pro, were identified within H9. The presence of Pro-containing peptides within H9 may contribute to its stability to digestive enzymes. Gluten hydrolysates may have antidiabetic potential for humans.
Asunto(s)
Inhibidores de la Dipeptidil-Peptidasa IV/química , Glútenes/química , Péptidos/química , Triticum/química , Secuencia de Aminoácidos , Dipeptidil Peptidasa 4/química , Humanos , Hidrólisis , Datos de Secuencia Molecular , Mapeo Peptídico , Espectrometría de Masas en TándemRESUMEN
Enzymatically hydrolysed milk proteins have a variety of biofunctional effects some of which may be beneficial in the management of type 2 diabetes mellitus. The purpose of this study was to evaluate the effect of commercially available intact and hydrolysed whey protein ingredients (DH 32, DH 45) on markers of the enteroinsular axis (glucagon like peptide-1 secretion, dipeptidyl peptidase IV inhibition, insulin secretion and antioxidant activity) before and after simulated gastrointestinal digestion (SGID). A whey protein hydrolysate, DH32, significantly enhanced (P < 0.05) insulin secretion from BRIN BD11 ß-cells compared to the positive control (16.7 mM glucose and 10 mM Ala). The whey protein hydrolysates inhibited dipeptidyl peptidase IV activity, yielding half maximal inhibitory concentration values (IC50) of 1.5 ± 0.1 and 1.1 ± 0.1 mg mL(-1) for the DH 32 and DH 45, samples respectively, and were significantly more potent than the intact whey (P < 0.05). Enzymatic hydrolysis of whey protein significantly enhanced (P < 0.05) its antioxidant activity compared to intact whey, as measured by the oxygen radical absorbance capacity assay (ORAC). This antioxidant activity was maintained (DH 32, P > 0.05) or enhanced (DH 45, P < 0.05) following SGID. Intact whey stimulated GLP-1 secretion from enteroendocrine cells compared to vehicle control (P < 0.05). This data confirm that whey proteins and peptides can act through multiple targets within the enteroinsular axis and as such may have glucoregulatory potential.
Asunto(s)
Diabetes Mellitus Tipo 2/metabolismo , Suplementos Dietéticos , Células Enteroendocrinas/metabolismo , Hipoglucemiantes/metabolismo , Células Secretoras de Insulina/metabolismo , Hidrolisados de Proteína/metabolismo , Proteína de Suero de Leche/metabolismo , Animales , Biomarcadores/metabolismo , Línea Celular , Fenómenos Químicos , Diabetes Mellitus Tipo 2/dietoterapia , Suplementos Dietéticos/análisis , Digestión , Inhibidores de la Dipeptidil-Peptidasa IV/química , Inhibidores de la Dipeptidil-Peptidasa IV/metabolismo , Inhibidores de la Dipeptidil-Peptidasa IV/uso terapéutico , Péptido 1 Similar al Glucagón/agonistas , Péptido 1 Similar al Glucagón/metabolismo , Hipoglucemiantes/química , Hipoglucemiantes/uso terapéutico , Insulina/agonistas , Insulina/metabolismo , Secreción de Insulina , Cinética , Ratones , Oxidantes/química , Oxidantes/metabolismo , Oxidantes/uso terapéutico , Estrés Oxidativo , Hidrolisados de Proteína/química , Hidrolisados de Proteína/uso terapéutico , Ratas , Proteína de Suero de Leche/química , Proteína de Suero de Leche/uso terapéuticoRESUMEN
The prevalence of type 2 diabetes mellitus (T2DM) is increasing and it is estimated that by 2030 approximately 366 million people will be diagnosed with this condition. The use of dipeptidyl peptidase IV (DPP-IV) inhibitors is an emerging strategy for the treatment of T2DM. DPP-IV is a ubiquitous aminodipeptidase that cleaves incretins such as glucagon like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), resulting in a loss in their insulinotropic activity. Synthetic DPP-IV drug inhibitors are being used to increase the half-life of the active GLP-1 and GIP. Dietary intervention is accepted as a key component in the prevention and management of T2DM. Therefore, identification of natural food protein-derived DPP-IV inhibitors is desirable. Peptides with DPP-IV inhibitory activity have been identified in a variety of food proteins. This review aims to provide an overview of food protein hydrolysates as a source of the DPP-IV inhibitory peptides with particular focus on milk proteins. In addition, the proposed modes of inhibition and structure-activity relationship of peptide inhibitors are discussed. Milk proteins and associated peptides also display insulinotropic activity and help regulate blood glucose in healthy and diabetic subjects. Therefore, milk protein derived peptide inhibitors may be a unique multifunctional peptide approach for the management of T2DM.
Asunto(s)
Glucemia/metabolismo , Diabetes Mellitus Tipo 2/dietoterapia , Proteínas en la Dieta/uso terapéutico , Inhibidores de la Dipeptidil-Peptidasa IV/uso terapéutico , Hipoglucemiantes/uso terapéutico , Péptidos/uso terapéutico , Hidrolisados de Proteína/uso terapéutico , Animales , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Dipeptidil Peptidasa 4/sangre , Polipéptido Inhibidor Gástrico/sangre , Péptido 1 Similar al Glucagón/sangre , Humanos , Hipoglucemiantes/farmacología , Proteínas de la Leche/uso terapéutico , Péptidos/farmacología , Hidrolisados de Proteína/farmacologíaRESUMEN
The effects of heat-induced denaturation of whey protein isolate (WPI) on the enzymatic breakdown of α-La, caseinomacropeptide (CMP), ß-Lg A and ß-Lg B were observed as hydrolysis proceeded to a 5% degree of hydrolysis (DH) in both unheated and heat-treated (80 °C, 10 min) WPI dispersions (100 g L(-1)). Hydrolysis of denatured WPI favoured the generation of higher levels of free essential amino acids; lysine, phenylalanine and arginine compared to the unheated substrate. LC-MS/MS identified 23 distinct peptides which were identified in the denatured WPI hydrolysate - the majority of which were derived from ß-Lg. The mapping of the detected regions in α-La, ß-Lg, and CMP enabled specific cleavage points to be associated with certain serine endo-protease activities. The outcomes of the study emphasise how a combined approach of substrate heat pre-treatment and enzymology may be used to influence proteolysis with attendant opportunities for targeting unique peptide production and amino acid release.
Asunto(s)
Proteínas de la Leche/química , Serina Endopeptidasas/química , Secuencia de Aminoácidos , Animales , Caseínas/química , Bovinos , Calor , Hidrólisis , Lactalbúmina/química , Lactoglobulinas/química , Espectrometría de Masas , Datos de Secuencia Molecular , Fragmentos de Péptidos/química , Mapeo Peptídico , Proteína de Suero de LecheRESUMEN
The beneficial effects of food-derived antioxidants in health promotion and disease prevention are being increasingly recognized. Recently, there has been a particular focus on milk-derived peptides; as a source of antioxidants, these peptides are inactive within the sequence of the parent protein but can be released during enzyme hydrolysis. Once released, the peptides have been shown to possess radical scavenging, metal ion chelation properties and the ability to inhibit lipid peroxidation. A variety of methods have been used to evaluate in vitro antioxidant activity, however, there is no standardised methodology, which hinders comparison of data. This review provides an overview on the generation of antioxidative peptides from milk proteins, the proposed mechanisms of protein/peptide induced antioxidant activity, in vitro measurement of antioxidant activity, in vivo evaluation of plasma antioxidant capacity and the bioavailability of antioxidative peptides. The understanding gained from other food proteins is referred to where specific data on milk-derived peptides are limited. The potential applications and health benefits of antioxidant peptides are discussed with a particular focus on the aging population. The regulatory requirements for peptide-based antioxidant functional foods are also considered.
Asunto(s)
Antioxidantes/química , Antioxidantes/farmacología , Enzimas/química , Leche/química , Péptidos/química , Péptidos/farmacología , Animales , Bovinos , Humanos , HidrólisisRESUMEN
Caseinophosphopeptides (CPPs), bioactive peptides released from caseins, have the ability to enhance bivalent mineral solubility. This is relevant to numerous biological functions in the oral cavity (promotion of tooth enamel remineralisation, prevention of demineralisation and buffering of plaque pH). Therefore, CPPs may play a positive role as prophylactic agents for caries, enamel erosion and regression of white spot lesions. Most in vitro and in situ studies demonstrate strong evidence for the bioactivity of CPPs in the oral cavity. Nevertheless, relatively little is known concerning their use as adjuvants for oral health and more particularly regarding their long-term effects on oral health.
Asunto(s)
Caseínas/metabolismo , Caries Dental/prevención & control , Fosfopéptidos/metabolismo , Erosión de los Dientes/prevención & control , Remineralización Dental/métodos , Animales , Fosfatos de Calcio/metabolismo , Caseínas/administración & dosificación , Caseínas/uso terapéutico , Sensibilidad de la Dentina/prevención & control , Sinergismo Farmacológico , Fluoruros/uso terapéutico , Humanos , Fosfopéptidos/químicaRESUMEN
The effects of heat-induced denaturation and subsequent aggregation of whey protein isolate (WPI) solutions on the rate of enzymatic hydrolysis was investigated. Both heated (60 °C, 15 min; 65 °C, 5 and 15 min; 70 °C, 5 and 15 min, 75 °C, 5 and 15 min; 80 °C, 10 min) and unheated WPI solutions (100 g L(-1) protein) were incubated with a commercial proteolytic enzyme preparation, Corolase PP, until they reached a target degree of hydrolysis (DH) of 5%. WPI solutions on heating were characterized by large aggregate formation, higher viscosity, and surface hydrophobicity and hydrolyzed more rapidly (P < 0.001) than the unheated. The whey proteins exhibited differences in their susceptibility to hydrolysis. Both viscosity and surface hydrophobicity along with insolubility declined as hydrolysis progressed. However, microstructural changes observed by light and confocal laser scanning microscopy (CLSM) provided insights to suggest that aggregate size and porosity may be complementary to denaturation in promoting faster enzymatic hydrolysis. This could be clearly observed in the course of aggregate disintegration, gel network breakdown, and improved solution clarification.
Asunto(s)
Proteínas de la Leche/química , Péptido Hidrolasas/química , Calor , Hidrólisis , Interacciones Hidrofóbicas e Hidrofílicas , Cinética , Conformación Proteica , Viscosidad , Proteína de Suero de LecheAsunto(s)
Endoscopía/historia , Reflujo Vesicoureteral/cirugía , Endoscopía/métodos , Endoscopía/estadística & datos numéricos , Historia del Siglo XX , Humanos , Irlanda , Procedimientos Quirúrgicos Urológicos/historia , Procedimientos Quirúrgicos Urológicos/métodos , Procedimientos Quirúrgicos Urológicos/estadística & datos numéricos , Reflujo Vesicoureteral/historiaRESUMEN
The objective of this study was to characterize the effects of pH, protein concentration and calcium supplementation on thermal stability, at 140°C, of soy protein isolate (SPI) and soy protein hydrolysate (SPH) ingredients. Increasing pH between 6.4 and 7.5 led to significantly (p<0.05) higher mean heat coagulation times (HCTs) at 140°C, for all soy protein ingredients at 1.8, and 3.6% (w/v) protein. Increasing protein concentration from 1.8 to 7.2% (w/v) led to shorter HCTs for protein dispersions. Calcium supplementation up to 850mg/L, except in the case of supplementation of SPI 1 with calcium citrate (CaCit), decreased HCT for soy protein ingredient dispersions, at pH 6.4 - 7.5. No significant differences (p<0.05) were found in mean HCT for dispersions supplemented with calcium chloride (CaCl2) and those supplemented with CaCit at 450, 650 and 850mg/L Ca(2+), in the pH range 6.4-7.5.
RESUMEN
Food proteins contain latent biofunctional peptide sequences within their primary structures which may have the ability to exert a physiological response in vivo. A large range of biofunctional peptides have been isolated from food proteins including opioid, immunomodulatory, antimicrobial, mineral binding, growth and muscle stimulating, anti-cancer, proteinase and angiotensin converting enzyme (ACE, EC 3.4.15.1) inhibitory peptides. The biofunctional peptide activity currently most studied in food proteins appears to be those that inhibit ACE. ACE plays a central role in the regulation of blood pressure (BP) through the production of the potent vasoconstrictor, angiotensin (Ang) II , and the degradation of the vasodilator, bradykinin (BK). ACE inhibitory peptides may therefore have the ability to lower BP in vivo by limiting the vasoconstrictory effects of Ang II and by potentiating the vasodilatory effects of BK. These ACE inhibitory peptides can be enzymatically released from intact proteins in vitro and in vivo during food processing and gastrointestinal digestion, respectively. ACE inhibitory peptides may be generated in or incorporated into functional foods in the development of 'natural' beneficial health products. Several products are currently on the market or are in development that contain peptide sequences which have ACE inhibitory properties. Detailed human studies are required in order to demonstrate the efficacy of these bioactive peptides prior to their widespread utilisation as physiologically beneficial functional foods/food ingredients.
Asunto(s)
Inhibidores de la Enzima Convertidora de Angiotensina , Proteínas en la Dieta , Alimentos , Hipertensión/tratamiento farmacológico , Fragmentos de Péptidos , Peptidil-Dipeptidasa A/metabolismo , Secuencia de Aminoácidos , Inhibidores de la Enzima Convertidora de Angiotensina/química , Inhibidores de la Enzima Convertidora de Angiotensina/farmacología , Inhibidores de la Enzima Convertidora de Angiotensina/uso terapéutico , Animales , Sitios de Unión , Humanos , Hipertensión/enzimología , Datos de Secuencia Molecular , Fragmentos de Péptidos/química , Fragmentos de Péptidos/farmacología , Fragmentos de Péptidos/uso terapéuticoRESUMEN
AIM: The aim of this report was to assess the effects of radiotherapy (RT) in children with abdominopelvic tumours in whom a biodegradable (Polyglactin 910) mesh had been inserted prior to commencement of radiotherapy. METHODS: Retrospective analysis was carried out of four patients with abdominopelvic tumours who underwent radiotherapy between 2000 and 2002 as part of their management. RESULTS: All children tolerated radiotherapy well with no evidence of acute or chronic radiation enteritis. One child developed prolonged postoperative ileus and a second child developed infective diarrhoea and fever, not related to radiation. CONCLUSION: We have highlighted a good tolerance of radiotherapy in children following the insertion of a Polyglactin 910 mesh prior to starting radiation and would recommend further larger studies with longer follow-up to support this.
Asunto(s)
Neoplasias Abdominales/radioterapia , Neoplasias Óseas/radioterapia , Enteritis/prevención & control , Traumatismos por Radiación/prevención & control , Mallas Quirúrgicas , Adolescente , Niño , Enteritis/etiología , Femenino , Humanos , Neoplasias Renales/radioterapia , Leiomiosarcoma/radioterapia , Masculino , Huesos Pélvicos , Neoplasias Pélvicas , Poliglactina 910/uso terapéutico , Músculos Psoas , Radioterapia/efectos adversos , Dosificación Radioterapéutica , Rabdomiosarcoma Embrionario/radioterapia , Sarcoma/radioterapia , Tomografía Computarizada por Rayos XRESUMEN
Pseudoaneurysms are uncommon following blunt abdominal trauma. A review of the literature has shown that such cases are usually managed aggressively. We report our experience of two cases of post traumatic intra-abdominal pseudoaneurysms which were managed conservatively.
Asunto(s)
Traumatismos Abdominales/complicaciones , Aneurisma Falso/terapia , Heridas no Penetrantes/complicaciones , Aneurisma Falso/etiología , Niño , Humanos , MasculinoRESUMEN
AIMS: To determine proteolytic enzyme activities released in Cheddar cheese juice manufactured using lactococcal starter strains of differing autolytic properties. METHODS AND RESULTS: The activities of residual chymosin, cell envelope proteinase and a range of intracellular proteolytic enzymes were determined during the first 70 days of ripening when starter lactococci predominate the microbial flora. In general, in cell free extracts (CFE) of the strains, the majority of proteolytic activities was highest for Lactococcus lactis HP, intermediate for L. lactis AM2 and lowest for L. lactis 303. However, in cheese juice, as ripening progressed, released proteolytic activities were highest for the highly autolytic strain L. lactis AM2, intermediate for L. lactis 303 and lowest for L. lactis HP. CONCLUSIONS: These results indicate that strain related differences in autolysis influence proteolytic enzyme activities released into Cheddar cheese during ripening. No correlation was found between proteolytic potential of the starter strains measured in CFE prior to cheese manufacture and levels of activities released in cheese juice. SIGNIFICANCE AND IMPACT OF THE STUDY: The findings further support the importance of autolysis of lactococcal starters in determining the levels of proteolytic activities present in cheese during initial stages of ripening.
Asunto(s)
Queso/microbiología , Microbiología de Alimentos , Lactococcus lactis/fisiología , Péptido Hidrolasas/metabolismo , Quimosina/metabolismo , Manipulación de Alimentos/métodos , L-Lactato Deshidrogenasa/metabolismoRESUMEN
Protein hydrolysates have a range of applications in the food and allied healthcare sectors. Bitterness is a negative attribute associated with most food protein hydrolysates. The development of biotechnological solutions for hydrolysate debittering is ongoing. Specific enzymatic debittering strategies have focused on the application of proline specific exo- and endopeptidases given the contribution of proline residues to peptide/hydrolysate bitterness. Hydrolysate manufacturing conditions may also play an important role in bitterness development. Practical solutions to hydrolysate debittering are likely to involve judicious choice of enzymatic processing conditions in conjunction with the use of peptidase activities having targeted hydrolytic specificity.
Asunto(s)
Tecnología de Alimentos/métodos , Hidrolisados de Proteína/química , Gusto , Aminopeptidasas/metabolismo , Caseínas/química , Caseínas/metabolismo , Endopeptidasas/metabolismo , Humanos , Hidrólisis , Modelos Químicos , Péptido Hidrolasas/metabolismo , Prolina/química , Prolina/metabolismo , Hidrolisados de Proteína/metabolismoRESUMEN
AIMS: To determine the influence of cheese cooking temperature on autolysis and permeabilization of two lactococcal starter strains in broth and in Cheddar cheese juice during ripening. METHODS AND RESULTS: Flow cytometry (FCM) was used to identify and enumerate intact and permeabilized cells in broth and in Cheddar cheese juice. Levels of intracellular enzyme activities were quantified concurrently. Permeabilized cell numbers increased for both strains in broth following a temperature shift from 32 to 38 degrees C and was accompanied by an increase in the level of accessible intracellular enzyme activities. The relative proportions of intact and permeabilized cell populations, as detected by FCM in cheese juice, changed during 42-day ripening. Permeabilized cell populations increased during ripening for both strains; however, an increase in accessible intracellular enzyme activity was observed only for the highly autolytic strain Lactococcus lactis AM2. CONCLUSIONS: Differences in the autolytic and permeabilization response induced by cooking temperature in two lactococcal strains affects intracellular enzyme accessibility in Cheddar cheese. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlights the importance of the autolytic and permeabilization properties of lactic acid bacteria starter strains and their impact on cheese ripening.
Asunto(s)
Queso/microbiología , Culinaria/métodos , Citometría de Flujo/métodos , Microbiología de Alimentos , Lactococcus/fisiología , Bacteriólisis , Permeabilidad de la Membrana Celular/fisiología , Recuento de Colonia Microbiana , Medios de Cultivo , Lactococcus/enzimología , Lactococcus/crecimiento & desarrollo , Lactococcus lactis/enzimología , Lactococcus lactis/crecimiento & desarrollo , Lactococcus lactis/fisiología , TemperaturaRESUMEN
The objectives of this study were to investigate the generation of beta-lactoglobulin fragment (142-148) (beta-LG f(142-148) during the hydrolysis of whey proteins, and the in vitro stability of this fragment upon incubation with gastrointestinal and serum proteinases and peptidases. An enzyme immunoassay (EIA) protocol was developed for the quantification of beta-LG f(142-148) in whey protein hydrolysates and in human blood serum. The minimum detection limit was 3 ng/mL. The level of the peptide in whey protein hydrolysates was influenced by the degree of hydrolysis (DH). As expected, highest levels of this peptide were found in hydrolysates generated with trypsin. Sequential incubation of hydrolysates at different DH values with pepsin and Corolase PP, to simulate gastrointestinal digestion, generally resulted in the degradation of beta-LG f(142-148) as determined by EIA. Reversed-phase HPLC and angiotensin-I-converting enzyme (ACE) activity assays demonstrated that synthetic beta-LG f(142-148) was rapidly degraded upon incubation with human serum. Furthermore, beta-LG f(142-148) could not be detected by EIA in the sera of 2 human volunteers following its oral ingestion or in sera from these volunteers subsequently spiked with beta-LG f(142-148). These in vitro results indicate that beta-LG f(142-148) is probably not sufficiently stable to gastrointestinal and serum proteinases and peptidases to act as an hypotensive agent in humans following oral ingestion. The in vitro methodology described herein has general application in evaluating the hypotensive potential of food protein-derived ACE inhibitory peptides.
Asunto(s)
Inhibidores de la Enzima Convertidora de Angiotensina/farmacología , Sistema Digestivo/metabolismo , Lactoglobulinas/química , Proteínas de la Leche/química , Proteínas de la Leche/metabolismo , Animales , Antihipertensivos/farmacología , Bovinos , Cromatografía Líquida de Alta Presión/veterinaria , Digestión , Sistema Digestivo/enzimología , Humanos , Hidrólisis , Técnicas para Inmunoenzimas/veterinaria , Técnicas In Vitro , Lactoglobulinas/farmacología , Proteínas de la Leche/farmacología , Fragmentos de Péptidos , Péptido Hidrolasas/metabolismo , Proteína de Suero de LecheRESUMEN
Angiotensin-I-converting enzyme (ACE, EC 3.4.15.1) plays a central role in the regulation of blood pressure in man. The objective of this study was to evaluate and modify the furanacryloyl-L-phenylalanylglycylglycine (FAPGG) assay method for quantification of ACE activity. The fixed time conditions developed for assay of ACE activity were as follows: 0.8 mM FAPGG, 175 + or - 10 units l(-1) ACE, incubation at 37 degrees C for 30 min and enzyme inactivation with 100 mM ethylenediaminetetra-acetic acid (EDTA). Hydrolysis of FAPGG to FAP and GG was quantified by measuring the decrease in absorbance at 340 nm. It was shown that increasing the level ACE activity in the assay from 155 to 221 + or - 15 units l(-1) resulted in a corresponding increase in the apparent IC(50) value for Captopril from 9.10 to 39.40 nM. Similar trends in the apparent IC50 values for a whey protein hydrolysate were obtained. The results demonstrate the requirement for carefully controlling ACE activity levels in the assay in order to obtained comparable and reproducible values for the inhibitory potency of ACE inhibitors.
Asunto(s)
Inhibidores de la Enzima Convertidora de Angiotensina/farmacología , Oligopéptidos/metabolismo , Peptidil-Dipeptidasa A/metabolismo , Animales , Captopril/farmacología , Glicilglicina/metabolismo , Hidrólisis , Concentración 50 Inhibidora , Proteínas de la Leche/metabolismo , Proteínas de la Leche/farmacología , Oligopéptidos/análisis , Peptidil-Dipeptidasa A/análisis , Conejos , Estándares de Referencia , Proteína de Suero de LecheRESUMEN
Gastrointestinal stromal tumors (GIST) in children are rare and their behavior has been regarded as difficult to predict on pathological criteria. We report our experience with two gastric GISTs in children aged 10 and 11 years. Both remain alive and free of disease at 5 years and 2 years respectively. Comparison of the pathological features in the resected specimens with a recently proposed guidelines for predicting outcome in this group of tumors is reported.