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Master's Dissertation
DOI
10.11606/D.46.1994.tde-24042012-124100
Document
Author
Full name
Sandro Roberto Marana
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1994
Supervisor
Committee
Terra, Clelia Ferreira (President)
Bianchi, Antonio Gildo de
Sampaio, Claudio Augusto Machado
Title in Portuguese
Distribuição intracelular de enzimas digestivas e caracterização das beta-glucosidases intestinais de Abracris flavolineata
Keywords in Portuguese
Abracris flavolineata
Beta-glucosidase
Biologia celular
Citologia
Enzimas (Metabolismo)
Abstract in Portuguese
Nas células do ceco anterior de A.flavolineata, a secreção de enzimas digestivas parece ser mediada por vesículas de secreção e é influenciada pelo tempo decorrido após a refeição. Fracionamentos subcelulares das células do ceco anterior realizados 3h após a refeição indicaram que a amilase, maltase, pNΦβglu hidrolase e aminopeptidase estão enriquecidas nas frações que contém os grânulos de secreção. γ glutamil transferase, aminopeptidase e dipeptidase apresentaram uma forma solúvel e outra ligada a membrana. No conteúdo do intestino de A. flavolineata foi possível detectar a presença de 3 β-glucosidases: 1, uma celobiase-aril β-glucosidase termoestável; 2, uma aril β-glucosidase termoinstável ativa sobre pNΦβglu; 3, uma alquil β-glucosidase. A celobiase-aril β-glucosidase hidrolisa celobiose e aril β-glucosídeos em sítios diferentes e é mais ativa sobre celobiose e laminaribiose que sobre aril β-glucosídeos sintéticos ou naturais. Moléculas anfipáticas ativam a alquil β-glucosidase, tornando esta enzima efetivamente ativa apenas na digestão de membranas. Esta enzima hidrolisa alquil β-glucosídeos com 6 a 11 carbonos no radical alquil. A celobiase-aril P-glucosidase e a alquil β-glucosidase são provavelmente responsáveis pela digestão "in vivo" de β-1,4; β-1,3; β-1,3-1,4 glucanas e glucosilceramidas, respectivamente.
Title in English
Intracellular distribution of digestive enzymes and characterization of the digestive beta-glucosidases from Abracris flavolineata
Keywords in English
Abracris flavolineata
Beta-glucosidase
Cellular biology
Citology
Enzymes
Abstract in English
The secretion of digestive enzymes in the anterior caecal cells of A. flavolineata seems to be mediated by secretory vesicles and influenced by the period of time after a meal. Subcellular fractions of anterior caecal cells were obtained by differential centrifugation of homogenates prepared 3 hours after a meal. Amylase, maltase, pNΦβglu hidrolase and aminopeptidase are found with high activities in fractions that correspond to the contents of secretory vesicles. γ glutamil transferase, aminopeptidase and dipeptidase presented soluble and membrane-bound forms. In A. flavolineata midgut contents we found 3 β-glucosidases: 1, a heat-stable cellobiase-aryl β-glucosidase; 2, a heat-unstable activity against pNΦ β glu (aryl β-glucosidase); 3, a alkyl β-glucosidase. The cellobiase-aryl β-glucosidase hydrolyzes cellobiose and aryl β-glucosides at different active sites and is more active on cellobiose and laminaribiose than on aryl β-glucosides. Amphipatic molecules activate the alkyl β-glucosidase, making the enzyme very active only during membrane digestion. This enzyme hydrolyzes alkyl β-glucosides with 6 to 11 carbons in alkyl moiety. The cellobiase-aryl β-glucosidase and alkyl β-glucosidase are probably responsible for in vivo digestion of β-1,4; β-1,3; β-1,3-1,4 glucans and glucosylceramides, respectively.
 
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Publishing Date
2012-04-24
 
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