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Isolation and characterization of milk coagulating gastric enzymes from bigeye tuna (Thunnus obesus)
Orientador(es)
Resumo(s)
Seis fracções proteolíticas activas de estômagos de atum foram separadas com o recurso ao "Rotofor IEF" e purificadas pelas técnicas cromatográficas de permeação de gel e de permuta iónica. A utilização de NaCl aumentou o rendimento do processo de extracção. O peso molecular da fracção pura mais activa, determinado pela técnica "SDS-PAGE", foi de 31.000 daltons. A composição amino-ácida obtida da mesma fracção diferiu da referida na literatura e a sua termoestabilidade, determinada por "DSC", evidenciou um pico de degradação à temperatura de 61.85 °C. A actividade da protease extraída de estômagos de atum às temperaturas de 14-26 °C, mostrou-se menos dependente da temperatura do que a do "rennet" comercial e perdeu toda a sua actividade acima de 40 °C.
ABSTRACT: Six proteolytic active fractions were separated from bigeye tuna stomachs by preparative IEF rotofor, and purified by gel permeation and ion-exchange chromatography. The presence of NaCl in the extraction process markedly enhanced the yield of tuna gastric enzyme. Molecular weight of the most active pure fraction by SDS-PAGE corresponded to a 31.000 daltons. The amino-acid composition of the same fraction differed slightly from literature values, and its thermostability determined by DSC, indicated peak denaturation temperature of 61.85 °C. The tuna protease activity at 14-26 °C was Iess temperature dependent than commercial rennet and completely lost the activity above 40 °C of temperature.
ABSTRACT: Six proteolytic active fractions were separated from bigeye tuna stomachs by preparative IEF rotofor, and purified by gel permeation and ion-exchange chromatography. The presence of NaCl in the extraction process markedly enhanced the yield of tuna gastric enzyme. Molecular weight of the most active pure fraction by SDS-PAGE corresponded to a 31.000 daltons. The amino-acid composition of the same fraction differed slightly from literature values, and its thermostability determined by DSC, indicated peak denaturation temperature of 61.85 °C. The tuna protease activity at 14-26 °C was Iess temperature dependent than commercial rennet and completely lost the activity above 40 °C of temperature.
Descrição
Palavras-chave
Thunnus obesus Patudo Bigeye Tuna Enzimas Gástricos Gastric Enzymes
Contexto Educativo
Citação
"ARQUIPÉLAGO. Ciências Biológicas e Marinhas = Life and Marine Sciences". ISSN 0873-4704. Nº 14A (1996): 75-84.