RESUMO
BACKGROUND: Baru (Dipteryx alata Vog.) is a fruit distributed throughout the Brazilian savanna and contains a seed with a high protein content, whose properties have been rarely explored. The purpose of this study was to characterize this protein, especially by isolation and quantifying its fractions and measuring some of its molecular properties. RESULTS: Baru seeds contain 244 g kg(-1) protein on a dry weight basis. Solubility profiles showed a preponderance of globulins. This fraction dominated the seed composition, with 61.7 wt% of the total soluble proteins. Albumins and glutelins accounted for 14 and 3.3 wt%, respectively. SDS-PAGE resolution of albumin and globulin showed main bands with molecular weights of 84 kDa and 64, 66 and 73 kDa, respectively. The total protein of the flour and the globulin showed values of in vitro digestibility of 85.59% and 90.54%, relative to casein. Total globulin produced only one chromatographic peak, both on Sepharose CL-6B gel filtration and on DEAE-cellulose ion-exchange columns, eluted at a concentration of 0.12 mol L(-1) NaCl. CONCLUSION: The baru seed had high protein content with large quantities of storage proteins. The chromatographic and solubility profiles indicate the predominance of a fraction with characteristics of a legumin-type protein.
Assuntos
Dipteryx/metabolismo , Proteínas de Armazenamento de Sementes/metabolismo , Sementes/metabolismo , Albuminas/química , Albuminas/isolamento & purificação , Albuminas/metabolismo , Animais , Proteínas Alimentares , Digestão , Globulinas/química , Globulinas/isolamento & purificação , Globulinas/metabolismo , Glutens/química , Glutens/isolamento & purificação , Glutens/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Hidrólise , Ponto Isoelétrico , Peso Molecular , Pancreatina/metabolismo , Pepsina A/metabolismo , Proteínas de Armazenamento de Sementes/química , Proteínas de Armazenamento de Sementes/isolamento & purificação , SolubilidadeRESUMO
Polyphenol oxidase (E.C. 1.14.18.1) (PPO) extracted from yacon roots (Smallanthus sonchifolius) was partially purified by ammonium sulfate fractionation and separation on Sephadex G-100. The enzyme had a molecular weight of 45 490+/-3500 Da and Km values of 0.23, 1.14, 1.34, and 5.0 mM for the substrates caffeic acid, chlorogenic acid, 4-methylcatechol, and catechol, respectively. When assayed with resorcinol, DL-DOPA, pyrogallol, protocatechuic, p-coumaric, ferulic, and cinnamic acids, catechin, and quercetin, the PPO showed no activity. The optimum pH varied from 5.0 to 6.6, depending on substrate. PPO activity was inhibited by various phenolic and nonphenolic compounds. p-Coumaric and cinnamic acids showed competitive inhibition, with Ki values of 0.017 and 0.011 mM, respectively, using chlorogenic acid as substrate. Heat inactivation from 60 to 90 degrees C showed the enzyme to be relatively stable at 60-70 degrees C, with progressive inactivation when incubated at 80 and 90 degrees C. The Ea (apparent activation energy) for inactivation was 93.69 kJ mol-1. Sucrose, maltose, glucose, fructose, and trehalose at high concentrations appeared to protect yacon PPO against thermal inactivation at 75 and 80 degrees C.
Assuntos
Asteraceae/enzimologia , Catecol Oxidase/isolamento & purificação , Raízes de Plantas/enzimologia , Carboidratos/farmacologia , Catecol Oxidase/química , Catecol Oxidase/metabolismo , Inibidores Enzimáticos/farmacologia , Temperatura Alta , Concentração de Íons de Hidrogênio , Cinética , Especificidade por SubstratoRESUMO
The albumin and globulin fractions from lentil seeds were isolated and characterised by gel filtration. The latter was shown to be homogeneous and the formet heterogeneous on PAGE, the aminoacid analysis revealed high values of amidic amino acids for both fractions with great differences in the sulphur-containing amino acids. Native albumin, globulin and salt-soluble proteins were markedly resistant to trypsin hydrolysis compared to casein. The SDS-PAGE of native salt-soluble proteins indicated that the globulin fragments (20 to 30kD) were slowly digested in the presence of albumin. The heating increased the hydrolysis of the proteins in the order: salt-soluble, albumin and globulin. The facilitated hydrolysis of the heated salt-soluble fraction seemed to be protein-protein interactions induced by heat