Heart ornithine decarboxylase from control and isoproterenol-treated rats: Kinetic properties, multiple forms and subcellular distribution

Flamigni, Flavio; Guarnieri, Carlo; Caldarera, Claudio Marcello

doi:10.1016/0306-3623(86)90007-8

Cited by 12 publications

(2 citation statements)

References 28 publications

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“…It is well known that ODC is a thiol-dependent enzyme [12][13][14][15][16][17][18], and exogenous, non-physiological thiols, usually DTT, are added to purification and assay buffers to avoid Actually, the activity of purified ODC depends on DTT concentration in the assay buffer, although it should be noted that high concentrations of DTT are inhibitory, particularly at low ornithine concentrations, resulting in an apparent increase in Km [23][24][25]. On the other hand, the physiological factor(s) and reducing system(s) involved in maintaining ODC in the active status are not known.…”

Section: Discussionmentioning

confidence: 99%

“…In this regard, microsomal oxidases may also play a role [15,19,26]. It is not clear if ODC is always in a fully reduced and thus activated status in vivo; however, differences have been found in various conditions in the requirement of DTT for maximal ODC activity [19,25]; furthermore, a decrease in the activity or stability of ODC has been observed in conditions associated with alteration of glutathione status [26,34]. In particular, the perfusion of rat heart with t-butyl hydroperoxide has been found to produce a fall in the GSH/GSSG ratio and an inhibition of ODC activity, which could be removed by adding DTT to the assay mixture or acetylcysteine to the perfusion medium [34].…”

Section: Discussionmentioning

confidence: 99%

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Rat liver cytosol contains NADPH- and GSH-dependent factors able to restore ornithine decarboxylase inactivated by removal of thiol reducing agents

Flamigni

Guarnieri

Caldarera

1988

Biochemical Journal

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Removal of dithiothreitol (DTT) from partially purified ornithine decarboxylase (ODC) led to an almost complete inhibition of enzymic activity. The inactivation was reversed by addition of millimolar concentrations of DTT, whereas natural reductants such as NADPH or NADH were ineffective, and GSH had only a limited effect. Addition of rat liver cytosol to the incubation mixture resulted in a noticeable re-activation of ODC; however, dialysed cytosol had little effect unless NADPH or GSH was present. Fractionation of rat liver cytosol by gel filtration on Sephadex G-75 yielded two fractions involved in the NADPH- and GSH-dependent re-activation of ODC: one designated 'A', eluted near the void volume (Mr greater than or equal to 60,000), and the other designated 'B', eluted later (Mr approx. 12,000). The NADPH-dependent mechanism required both fractions A and B for maximal ODC re-activation; the most effective concentration of NADPH was 0.15 mM, although a significant effect was observed at a concentration more than 10-fold lower. The GSH-dependent mechanism involved the mediation of Fraction B only, and operated at millimolar concentrations of GSH. These results suggest the existence of reducing systems in the cytosol, which may play a role in maintaining, and potentially in regulating, ODC activity by modulation of its thiol status.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Rat liver cytosol contains NADPH- and GSH-dependent factors able to restore ornithine decarboxylase inactivated by removal of thiol reducing agents

Flamigni

Guarnieri

Caldarera

1988

Biochemical Journal

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Ornithine decarboxylase properties: Is there a role for a microsome‐bound inactivating activity?

Zuretti

Brossa

Gili

et al. 1988

Cell Biochemistry & Function

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Liver microsomes have a strong ornithine decarboxylase (ODC) inactivating capacity in vitro. The present results suggest that this may be involved in regulation of ODC activity in vivo: (1) the O D C inactivating capacity of microsomes appears susceptible to in vivo modulation: a single administration of thioacetamide, which induces ODC, also causes a significant increase in the inactivating capacity of the microsomes; (2) under conditions leading to increased microsome-bound ODC-inactivating capacity (e.g. liver from thioacetamide-treated rates versus regenerating liver) ODC displays a greater thermal lability and inactivability in virro.A possible involvement of this microsomal activity in an autoregulatory pathway of O D C is suggested by the fact that it is induced by the administration of polyamines. However, inhibition of ODC activity by a-difluoromethylornithine does not prevent the increase of the microsomal activity caused by thioacetamide. Thus, polyamine biosynthesis does not appear to be an absolute requirement for induction of the microsomal ODC-inactivating capacity.The apparent half-life of O D C in vivo, as evaluated after cycloheximide administration, does not appear to correlate with the microsomal ODC-inactivating capacity content and the stability properties of O D C in vitro.

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L-Arginine at the Crossroads of Biochemical Pathways Involved in Myocardial Hypertrophy

Giordano

Shantz

Hillary

et al. 2003

Signal Transduction and Cardiac Hypertrophy

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Heart ornithine decarboxylase from control and isoproterenol-treated rats: Kinetic properties, multiple forms and subcellular distribution

Cited by 12 publications

References 28 publications

Rat liver cytosol contains NADPH- and GSH-dependent factors able to restore ornithine decarboxylase inactivated by removal of thiol reducing agents

Rat liver cytosol contains NADPH- and GSH-dependent factors able to restore ornithine decarboxylase inactivated by removal of thiol reducing agents

Ornithine decarboxylase properties: Is there a role for a microsome‐bound inactivating activity?

L-Arginine at the Crossroads of Biochemical Pathways Involved in Myocardial Hypertrophy

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