Stimulation of ornithine decarboxylase activity and inhibition of S-adenosyl-l-methionine decarboxylase activity in leukaemic mice by methylglyoxal bis(guanylhydrazone)

Administration of methylglyoxal bis(guanylhydrazone) to leukaemic mice results in an early depression followed by a marked elevation of S-adenosyl-l-methionine decarboxylase activity. Further, there is an early prolonged increase in the activity of ornithine decarboxylase, the initial enzyme in the polyamine biosynthetic pathway. Because of the profound effects of methylglyoxal bis(guanylhydrazone) in vivo on the polyamine biosynthetic pathway, the drug can no longer be considered a specific inhibitor of spermidine synthesis.

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The in vivo stimulation of rat liver ornithine decarboxylase activity by dibutyryl cyclic adenosine 3′,5′-monophosphate, theophylline and dexamethasone

Biochemical and Biophysical Research Communications ◽

10.1016/0006-291x(72)90904-7 ◽

1972 ◽

Vol 48 (6) ◽

pp. 1649-1655 ◽

Cited By ~ 86

Author(s):

William T. Beck ◽

Rill A. Bellantone ◽

E.S. Canellakis

Keyword(s):

Ornithine Decarboxylase ◽

Rat Liver ◽

Decarboxylase Activity ◽

Ornithine Decarboxylase Activity ◽

Stimulation Of

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Role of pyridoxal phosphate in mammalian polyamine biosynthesis. Lack of requirement for mammalian S-adenosylmethionine decarboxylase activity

Biochemical Journal ◽

10.1042/bj1660081 ◽

1977 ◽

Vol 166 (1) ◽

pp. 81-88 ◽

Cited By ~ 19

Author(s):

A E Pegg

Keyword(s):

Ornithine Decarboxylase ◽

Pyridoxal Phosphate ◽

Vitamin B ◽

Decarboxylase Activity ◽

Deficient Diet ◽

Polyamine Biosynthesis ◽

Adenosylmethionine Decarboxylase ◽

Ornithine Decarboxylase Activity

1. Polyamine concentrations were decreased in rats fed on a diet deficient in vitamin B-6. 2. Ornithine decarboxylase activity was decreased by vitamin B-6 deficiency when assayed in tissue extracts without addition of pyridoxal phosphate, but was greater than in control extracts when pyridoxal phosphate was present in saturating amounts. 3. In contrast, the activity of S-adenosylmethionine decarboxylase was not enhanced by pyridoxal phosphate addition even when dialysed extracts were prepared from tissues of young rats suckled by mothers fed on the vitamin B-6-deficient diet. 4. S-Adenosylmethionine decarboxylase activities were increased by administration of methylglyoxal bis(guanylhydrazone) (1,1′-[(methylethanediylidine)dinitrilo]diguanidine) to similar extents in both control and vitamin B-6-deficient animals. 5. The spectrum of highly purified liver S-adenosylmethionine decarboxylase did not indicate the presence of pyridoxal phosphate. After inactivation of the enzyme by reaction with NaB3H4, radioactivity was incorporated into the enzyme, but was not present as a reduced derivative of pyridoxal phosphate. 6. It is concluded that the decreased concentrations of polyamines in rats fed on a diet containing vitamin B-6 may be due to decreased activity or ornithine decarboxylase or may be caused by an unknown mechanism responding to growth retardation produced by the vitamin deficiency. In either case, measurements of S-adenosylmethionine decarboxylase and ornithine decarboxylase activity under optimum conditions in vitro do not correlate with the polyamine concentrations in vivo.

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