Quanto è utile/interessante questa discussione:
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Army
Nuovo Arrivato
Prov.: Napoli
Città: napoli
30 Messaggi |
 Inserito il - 12 maggio 2008 : 09:26:24
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ciao ragazzi
sto preparando un seminario su un articolo che tratta l'isocitrato deidrogenasi NADP nei microsomi, sto riscontrando problemi sulla latenza perchè mi mette una tabella e non la riesco a comprendere a pieno!!!
ma cosa si intende per latenza, come fa ad aumentare e diminuire? il substrato e il prodotto influiscono?
anche se conoscete qualche sito o altro dove posso andare a cercare!
Grazie mille
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Army
Nuovo Arrivato
Prov.: Napoli
Città: napoli
30 Messaggi |
Inserito il - 12 maggio 2008 : 10:41:58
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vi allego questa parte dell'articolo
Isocitrate- and malate-dependent NADPH generation
was investigated in rat liver microsomes to test whether
beside hexose-6-phosphate dehydrogenase other NADPH
producing enzymes are also present in the endoplasmic
reticulum. In parallel measurements the vesicles were permeabilized
to allow the free accessibility of NADP+ to
the intraluminal enzymes. As a control, glucose-6-phosphate-
dependent NADPH generation—attributable to hexose-
6-phosphate dehydrogenase activity [11]—was also
detected. All the three substrates promoted NADP+ reduction
in intact microsomes, although at different extent
(Table 1).
Permeabilization of the vesicles significantly increased
the activity in all cases. However, while the calculated
latency was almost complete in case of hexose-6-phosphate
dehydrogenase activity, the latency of isocitrateor
malate-dependent NADP+ reduction was lower (Table
1). Since the latency is mainly due to the minimal permeability
of pyridine nucleotides through the microsomal
membrane [27], we supposed that cytosolic proteins
attached to the outer surface of the vesicles are responsible
for the non-latent part of the activity. Therefore,
loosely associated proteins were removed by using a
polyethylene glycol wash. This maneuver has been successfully
used by us and others previously to purify the
microsomal vesicles [31,35–37]. In fact, in polyethylene
glycol-washed vesicles the non-latent part of the activities
became negligible and the latency was over 90% in all
cases.
The results of the polyethylene glycol-wash method were
further validated by treating the intact vesicles with trypsin.
After the treatment the trypsin-accessible extravesicular
activity was dramatically decreased and the latency significantly
increased (Table 1).
Coenzyme-specificity of isocitrate- and malate-dependent
activities was also investigated. While the isocitrate-dependent
reaction showed a very low velocity with NAD+, the
malate dependent one was even faster (Table 1).
Grazie mille
HELP!!!!!!!!!!!
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latenza, isocitrato deidrogenasi NADP
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