Caracterização e hidrólise in vitro da globulina principal de grão-de-bico (Cicer arietinum L.), var. IAC-Marrocos

Abstract

RESUMONo presente estudo procedeu-se ao isolamento e caracterização da fração globulina majoritária (11 S) de grão-de-bico, var. IACMarrocos. A globulina majoritária extraída foi isolada por cromatografia de filtração em gel e de troca-iônica mostrando apenas uma banda de proteína na eletroforese em gel de poliacrilamida. A globulina majoritária, após passagem em coluna de Sephadex, revelou duas bandas protéicas de 55 e 52,5kDa e três bandas menores em gel de poliacrilamida dodecilsulfato de sódio. Na presença de 2-mercaptoetanol 6 polipeptídios na faixa de 18 a 42kDa foram revelados na eletroforese. A globulina isolada foi submetida à ação da tripsina e quimotripsina onde a forma nativa mostrou-se resistente à ação enzimática enquanto o aquecimento (96 e 121°C/ 15min) não foi suficiente para aumentar a susceptibilidade à hidrólise, significativamente. Adição de NaCl 0,3M levou a um aumento da estabilidade estrutural com menor susceptibilidade à digestão proteolítica, fato em parte perdido com o aquecimento. As hidrólises foram acompanhadas por eletroforese em gel de poliacrilamida dodecilsulfato de sódio. Palavras-chave: grão-de-bico; Cicer arietinum L.; globulina majoritária; caracterização; hidrólise in vitro. SUMMARY CHARACTERIZATION AND in vitro TRYPTIC HYDROLYSIS OF THE MAJOR GLOBULIN FROM CHICKPEA (Cicer arietinum L.).The isolation and characterization of the major globulin fraction (11 S) from Chickpea, vc IAC-Marrocos, were evaluated. The major globulin was extracted, isolated by gel filtration and ion-exchange chromatography showing only one protein band on PAGE. The globulin, after Sephadex elution, revealed two protein bands of 55 and 52.5kDa and three minor bands on SDS-PAGE. In the presence of 2-mercaptoethanol six polypeptides were revealed on SDS-PAGE in the range of 18 to 42kDa. The isolated native globulin shown to be resistant to trypsin and chymotrypsin however heating at 96 and 121ºC/15min was not sufficient to increase the hydrolysis significantly. The proteolytic susceptibility of the enzymes was reduced by 0.3M NaCl addition at the assay. The salt concentration was sufficient to stabilize the native protein structure that was lost after heating as demonstrated on SDS-PAGE.

Isolation, solubility and in vitro hydrolysis of chickpea vicilin-like protein

“…A similar low solubility tendency was observed at 0.2 mol/L concentration in the pH 4.5-5.0 range: however, at both 0.5 and 1.0 mol/L NaCl, chickpea vicilin shows high solubility (480%) above pH 4.0 and low solubility (o30%) at or below pH 3.0. These profiles resemble those already reported for several legume proteins (Carbonaro et al, 1997;Neves et al, 2004).…”

“…The solubility increased up to a maximum of about 95% at salt concentrations above 0.4 mol/L NaCl. This high solubility of chickpea vicilin at 0.2 mol/L NaCl makes it possible to isolate it from the legumin; thus the adopted procedure includes dilution of NaCl to 0.17 mol/L, a condition in which the chickpea legumin is practically insoluble (Neves et al, 2004). Vicilin solubility in water and in 0.2, 0.5 and 1.0 mol/L NaCl, at pH values from 1 to 12, is shown in Fig.…”

Chemical and nutritional evaluation of kernels of bocaiuva, Acrocomia aculeata (Jacq.) Lodd.

“…The digestibility of the glutelin fraction of bocaiuva was also lower than that reported in the literature for the karkade protein [1] though similar to that of legume seed proteins, such as the chickpea and jojoba [23,31].…”

“…Isolation of seed proteins has revealed that many plants (including Leguminosae) contain globulins as the main storage protein (50-75% of total seed protein) [5,7,23,31]. Studies regarding the degradation of legume proteins, particularly globulins, have demonstrated that cooking and fermentation separates this protein fraction from antinutritional factors, such as proteinase inhibitors and lectins, which is a feature that makes globulin suitable for studies concerning the nutritional value of proteins [5,7].…”

Partial characterization of proteins from baru (Dipteryx alataVog) seeds

“…In vitro protein digestibility for the flour and globulin fraction from baru seed were lower than those found for casein ( P < 0.05) (Table 3). However, the values of in vitro digestibility reported for the proteins of legumes such as broad bean ( Vicia faba L.), lentil ( Lens culinaris Medikus), chickpea ( Cicer arietinum L.) and beans ( Phaseolus vulgaris L.) are between 73 and 83% 20, 28. The greater digestibility of the globulins relative to the flour protein ( P < 0.05) suggests the presence of other natural components in the seed that interact with proteins or enzymes and hinder the hydrolysis, especially the albumin fraction, which may contain seed protease inhibitors 21…”