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Master's Dissertation
DOI
https://doi.org/10.11606/D.11.1982.tde-20220207-181312
Document
Author
Full name
Dulce Maria Junqueira Aires Silva
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 1982
Supervisor
Title in Portuguese
Estudo comparativo da composição polipeptídica de cultivares de arroz (Oryza sativa, L.)
Keywords in Portuguese
ARROZ
COMPOSIÇÃO QUÍMICA
POLIPEPTÍDEOS
VARIEDADES VEGETAIS
Abstract in Portuguese
Neste trabalho, foi efetuado um estudo comparativo das composições polipeptídicas e de aminoácidos do grão de oito cultivares de arroz e de duas amostras de arroz comercial. Os teores de proteínas das amostras foram determinados através de análise da farinha melo método de Kjeldahl e as composições de aminoácidos foram determinadas por hidrólise ácida da farinha, através de um analisador automático. Os perfis polipeptídicos das amostras foram obtidos por eletroforese em gel de poliacrilamida, de acordo com os métodos de WEBER e OSBORN (1969) e LAEMMLI (1970), para gel em coluna, e o método de LAEMMLI modificado, em placas. Os teores de proteínas das amostras variaram de 9,2% a 12,8% entre as cultivares e de 8,1% a 8,3% nas amostras de arroz comercial parabolizado e beneficiado. Pequena variação foi encontrada entre as composições em aminoácidos das cultivares. Os aminoácidos que apresentaram maiores teores foram o ácido glutâmico, ácido aspártico, glicina e leucina, e os que apresentaram menores teores foram histidina, lisina e treonina, sendo que o teor de lisina variou de 2,7 a 3,3 moles %. A maioria dos polipeptídios extraídos de cada amostra apresentou PMS compreendidos entre 14000 e 68000. Três grupos de polipeptídios com PMS de 35000, 25000 e 14000 foram os principais em cada perfil do grão total e do endosperma, mas não do embrião. Os perfis com relação aos polipeptídios de 25000 e 35000 não foram idênticos em todas as amostras. Este trabalho demonstra que os métodos eletroforéticos podem ser usados para detectar diferenças na composição polipeptídica entre amostras de arroz, inclusive variedades tradicionais, linhagens novas produzidas em programas de melhoramento e também amostras empregadas em estudos nutricionais.
Title in English
A study of the polypeptide compositions of rice (Oryza sativa L.) cultivars
Abstract in English
ln this work, a comparative study of amino acid and polypeptide compositions of eight rice grain cultivars and two commercial samples of rice is reported. The protein contents of samples were determined from Kjeldahl-N analysis of meals and amino acid compositions were determined by analysis of acid hydrolysates of meal by use of an automatic amino acid analyzer. Profiles of the polypeptide compositions of samples were prepared by use of electrophoresis in polyacrylamide gels according to the methods of WEBER and OSBORN (1969), and LAEMMLI (1970) for gel columns and a modified method of LAEMMLI (1970) for gels slabs. The protein contents of samples varied from 9.2% to 12.8% among cultivars and ranged from 8.1% to 8.3% in commercial samples of parboiled and milled rice. Little variation was found among the amino acid compositions of the cultivars, and the amino acids present in highest concentration in the hydrolysates were glutamic and aspartic acid, glycine and leucine. Those in lowest concentration were histidine, lysine and threonine. However, lysine content ranged from 2.7 to 3.3 moles %. Most of the polypeptides extracted from each sample presented MWS between 14000 and 68000. Three groups of polypeptides with MWW 35000, 25000 and 14000 were the most prominent in each profile of whole grain and endosperm but not of embryo. However, the patterns of polypeptides within the groups with MW 25000 and 35000 were not identical in all samples. The work demonstrates that electrophoretic procedures may be useful for the detection of differences in polypeptide composition among rice samples, including traditional varieties new lines produced during improvement programs and samples employed in nutritional studies.
 
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Publishing Date
2022-02-07
 
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