• JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
 
  Bookmark and Share
 
 
Doctoral Thesis
DOI
10.11606/T.9.1989.tde-20032008-110739
Document
Author
Full name
Beatriz Rosana Cordenunsi
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1989
Supervisor
Committee
Lajolo, Franco Maria (President)
Areas, Jose Alfredo Gomes
Chitarra, Adimilson Bosco
Rosa, Rubens
Terra, Nelcindo Nascimento
Title in Portuguese
Síntese da sacarose no amadurecimento da banana. Envolvimento da sacarose sintetase e sacarose fosfato sintetase
Keywords in Portuguese
Banana
Enzimas
Sacarose
Sacarose fosfato sintetase
Sacarose sintetase
Abstract in Portuguese
A sacarose sintetase pode ser extraída de bananas pré-climatéricas cisteína (0,02M), em tampão tris-HCl pH 8,0 (0,05M), contendo EDTA (O,OlM), PVP (1%) e bissulfito de sódio (0,02M) na proporção de 1:4 (massa de banana/volume desolução f extratora). O seu isolamento pode ser efetuado por precipitação com sulfato de amônio, cromatografia por peneira molecular seguida de troca iônica ou, alternativ~ente, por cromatografia apenas em troca iônica. Obtém-se assim preparações com atividade específica entre 0,42 e 6,11 e grau de purificação de 5 a 18 vezes. A enzima purificada tem elevada afinidade por UDPG (Km = 0,67), UDP (Km = O, 17) , frutose (Km = 0,31) e reduzida afinidade para a sacarose (Km = 22,7). A enzima está presente durante a fase de desenvolvimento do fruto até o período préclimatérico, quando sua atividade sintética e hidrolítica tende a desaparecer a medida que aumenta o tempo decorrido após a colheita. Contrariamente, a sacarose fosfato sintetase não é detectada nas fases iniciais de desenvolvimento do fruto, mas tem sua atividade aumentada durante o amadurecimento, concomitantemente ao desaparecimento do amido. A sacarose fosfato sintetase e não a sacarose sintetase pode estar envolvida na transformação amido-sacarose durante o amadurecimento.
Title in English
Sucrose synthesis during banana ripening: sucrose synthetase and sucrose phosphate synthetase involviment
Keywords in English
Banana
Enzymes
Sucrose
Sucrose phosphate synthetase
Sucrose synthetase
Abstract in English
Banana sucrose synthetase can be purified almost to homogeneity by extraction with tris-HCl pH 8.0 (0.05M) buffer containing cystein (0.02M), EDTA (O.OlM), PVP (1%) and NaHS03 (O.O2M), ammonium sulfate precipitation, followed by cromatography on DEAE-cellulose (or alteratively on Sepharose-6B followed by DEAE-cellulose). The purified enzyme activities has high affinity for UDPG (Km = 0.67), UDP (Km = 0.17), fructose (Km = 0.31) and low affinity for sucrose (Km = 22.7). The sucrose synthetase is present during all stages of fruit development until the climateric when its activity tends to disappear, as the time after harvesting decurs contrarily the activity of sucrose phosphate synthetase is not detected in the initial stages of development but its activity increases during ripening following starch desappearance. Sucrose phosphate synthetase instead of sucrose synthetase may be involved in starch-sucrose conversion in post-harvest bananas.
 
WARNING - Viewing this document is conditioned on your acceptance of the following terms of use:
This document is only for private use for research and teaching activities. Reproduction for commercial use is forbidden. This rights cover the whole data about this document as well as its contents. Any uses or copies of this document in whole or in part must include the author's name.
Publishing Date
2008-03-20
 
WARNING: Learn what derived works are clicking here.
All rights of the thesis/dissertation are from the authors
Centro de Informática de São Carlos
Digital Library of Theses and Dissertations of USP. Copyright © 2001-2021. All rights reserved.