Identificação e caracterização de glubulina, albumina e lectina, e analise destas durante a formação e germinação da semente de tres variedades de Phaseolus vulgaris

AUTOR(ES)
DATA DE PUBLICAÇÃO

1994

RESUMO

Seeds of Phaseolus vulgaris cv. Norh, Jalo and Ouro Negro were analyzed for several aspects: contents of total protein and protein fractions (albumins, globulins, lectins), electrophoretic banding patterns, carbohydrate content and haemagglutinating activity of the lectin fractions. In addition, the accumulation of these fractions during seed maturation and the mobilization during germination were also investigated. The concentration of total protein in the seeds varied from 20% (cv. Ouro Negro) to 26% (cv. Jalo and cv. Norh). The globulin concentration in the seed protein fraction varied from a minimum of 48% (cv. Jalo) up to a maximum of 72% (cv. Norh), while that for cv. Jalo amounted up to approx. 60%. On the other hand, the albumin fraction in the seed protein of cv. Jalo and cv. Norh (approx. 11 %) was found to be within the range found for the majority of the varieties cultivated all over the world. However this same concentration in cv. Ouro Negro was surprisingly elevated (17%). Irrespectively of the Phaseolus varieties, our study indicated that the main 7S globulin (Phaseolin), comprised over 70% of the total globulin fraction. It was also observed that a small part of this fraction was found to be comprised of lectins. The values ranged from approx. 10% (cv. Jalo), to approx. 15% (cv. Norh and cv. Ouro Negro). Interestingly, the amounts of albumin containing haemagglutinating activity were high in these varieties. Thus of the total albumin concentration in the cv. Jalo, at lest 15% was considered to be lectin. These values were still higher for the other varieties (approx. 40%). The investigation of the presence of carbohydrates in the protein fractions, indicated as expected that the globulins contained a minimum amount of 3% of carbohydrate in the molecule. However this same amount of carbohydrate in the albumin fractions was surprisingly higher that observed for the globulins. Thus both fractions were found to be glycoproteins. In this study was also investigated the structure of the 7S globulin in SDSPAGE. The results indicated that all the phaseolins were similar in that they were all composed of at least three main subuníts ranging in size from 41 to 47 kDa, indicating that these varieties belong the well established group "Tendergreen". Experiments designed to investigate the accumulation of the main 7S globulin in the seeds, during the seed development, have revealed a linear relationship of protein accumulation with time in the varieties studied. On the other hand, phaseolin degradation during seed germination was different in the 3 varieties: it was linearly correlated with time in cv. Jalo and it presented a exponencial pattern in cv. Norh and cv. Ouro Negro. The results indicated that besides the well known globulin fractions the albumins can also be considered as storage proteins

ASSUNTO(S)

albumina lectinas

ACESSO AO ARTIGO

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