RESUMO
Alpha-gliadins isolated by carboxymethylcellulose chromatography contain noncovalently bound glucose probably due to contaminating proteoglycans and to material shed from the column. Traces of carbohydrate remain strongly bound to alpha-gliadins even after harsh denaturation, but our results indicate alpha-gliadins are not glycoproteins. Suggestions that gliadins are glycoproteins are probably due to contamination with this glucose and the presence of these proteoglycans.
Assuntos
Celulase , Gliadina/metabolismo , Glicosídeo Hidrolases/química , Gliadina/isolamento & purificação , Glicosídeo Hidrolases/metabolismo , Glicosilação , Espectrometria de Massas , Proteoglicanas/química , Proteoglicanas/metabolismo , Triticum/químicaRESUMO
BACKGROUND: Much effort has been expended in the search for an endogenous inhibitor of the cellular sodium/potassium pump, a compound of major physiological importance, which has been implicated in the mechanism of essential hypertension. Others have suggested that ouabain or an isomer of ouabain may be the endogenous pump inhibitor. Neonatal cord serum contains an inhibitor of the sodium pump; we attempted to isolate and characterise this substance from human placentas. METHODS: Homogenised placentas were dialysed and the resulting solutes were trapped on octadecylsilyl silica and then separated by high-performance liquid chromatography. Measurement of the activity of the sodium pump of human leucocytes was used to test each fraction for the presence of the inhibitor. FINDINGS: An inhibitor of the sodium pump was obtained by this technique in a mass spectrometrically pure form with a mass of 370 Da, an empirical formula of C24H34O3 and only one hydroxyl group. The characteristic fragmentation pattern observed in negative-ion mass spectrometry was compared with those of various model compounds; this comparison suggested that the active material was a dihydropyrone-substituted steroid. INTERPRETATION: These results suggest that a dihydropyrone-substituted steroid is an endogenous regulator of the sodium pump in humans and, presumably, other mammals. Proof of the endogenous origin will require the demonstration of a previously unrecognised biosynthetic pathway.
Assuntos
Bufanolídeos/isolamento & purificação , Leucócitos/efeitos dos fármacos , Placenta/química , ATPase Trocadora de Sódio-Potássio/antagonistas & inibidores , Bufanolídeos/química , Bufanolídeos/farmacologia , Cromatografia Líquida de Alta Pressão , Feminino , Humanos , Leucócitos/metabolismo , Estrutura Molecular , Espectrometria de Massas de Bombardeamento Rápido de ÁtomosAssuntos
Gliadina/genética , Gliadina/isolamento & purificação , Sequência de Aminoácidos , Doença Celíaca/etiologia , Cromatografia Líquida de Alta Pressão , Eletroforese Capilar , Gliadina/toxicidade , Humanos , Dados de Sequência Molecular , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por MatrizAssuntos
Cromatografia Líquida de Alta Pressão/métodos , Cadeias Leves de Imunoglobulina/química , Cadeias Leves de Imunoglobulina/genética , Espectrometria de Massas de Bombardeamento Rápido de Átomos/métodos , Sequência de Aminoácidos , Animais , Anticorpos Monoclonais/química , Anticorpos Monoclonais/genética , Camundongos , Dados de Sequência Molecular , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/genética , Mapeamento de PeptídeosRESUMO
A high-performance liquid chromatography protocol has been developed for the analysis of snake venoms. This system has been used to isolate eight fractions from Malayan pit viper (Calloselasma rhodostoma) venom. The fractions have been analysed using electrospray mass spectrometry. A number of major components were found with masses ranging from 13,670 to 22,750 Da.
Assuntos
Venenos de Víboras/análise , Cromatografia Líquida de Alta Pressão , Indicadores e Reagentes , Espectrometria de MassasRESUMO
A proportion of epithelial lymphocytes in various mammalian species is characterised by cells containing cytoplasmic granules. We have studied the total number of granular lymphocytes within surface and crypt epithelium of jejunal mucosae (per 10(4) micron2 muscularis mucosae) from six groups of subjects, comprising (i) young healthy volunteers (ii) family relatives of known coeliac patients, patients with gastrointestinal disorders associated with either (iii) normal or (iv) "flat" mucosae, and groups of (v) untreated and (vi) treated patients with coeliac disease. There was no difference in the absolute number of gEL between the three control groups with normal mucosal architecture, the proportion of granular to total EL per unit of tissue varying between 30-40%. In untreated coeliac mucosae, there was a significantly increased population of gEL, compared with the same control groups (p less than 0.001): the ratio of granular to total EL approximated 65%, and did not differ from flat-control mucosae in which the proportion of gEL was 55%. On withdrawal of gluten, the absolute number of gEL fell significantly in comparison with the untreated coeliac group (p less than 0.05). To further evaluate the effect of gluten challenge, granular lymphocytes were monitored during a five-day period in groups of treated coeliac patients orally challenged with increasing doses (500-3000 mg) of a peptic-tryptic digest of gluten. A significant rise in the absolute number of granular lymphocytes occurred at 12 h, but without any deterioration in mucosal architecture.
Assuntos
Doença Celíaca/patologia , Jejuno/citologia , Tecido Linfoide/patologia , Adolescente , Adulto , Idoso , Células Epiteliais , Humanos , Mucosa Intestinal/citologia , Jejuno/patologia , Lactoglobulinas/farmacologia , Linfócitos/citologia , Tecido Linfoide/citologia , Pessoa de Meia-IdadeRESUMO
The positive- and negative-ion mass spectra of [methionine]enkephalin and [leucine]enkephalin have been obtained by using a fast-atom-bombardment source described previously by Barber, Bordoli, Sedgwick & Tyler [(1981) J. Chem. Soc. Chem. Commun., in the press]. This technique has allowed the spectra to be obtained without conversion of the enkephalins into volatile derivatives. The fast-atom-bombardment spectra show good pseudo-molecular-ion sensitivity and fragmentation that can be interpreted on the basis of the known molecular structure.