Vol.4, No 1, 1997 pp. 17 - 22
UC 578.083
EFFECT OF PYRIDOXINE ON THE ALKALINE RIBONUCLEASE
ACTIVITY IN THE LIVER OF DEXAMETHASONE TREATED RATS
Gordana
Bjelaković, Dušica Pavlović, Jelenka Nikolić,Gordana Kocić, Bojana Stanković,
Bojko Bjelaković
Institute of Biochemistry, Faculty of Medicine, Niš, Serbia, Yugoslavia
Summary. Alkaline ribonuclease activity (pH 7.8) is present in most
mammalian cells in both the free form and bound to an inhibitor protein.
It has been recently suggested that pyridoxal-5-phosphate interacts
with ?-amino groups of lysine in human pancreatic ribonuclease. There is
evidence that the nuclear binding of glucocorticoid-receptor complex can
be inhibited by pyridoxal phosphate.
The data presented here suggest that treatment of experimental animals
with dexamethasone during a 7- day period causes a decrease of alkaline
RNase activities (total, free and latent RNases). In "in vitro" experimental
condition dexamethasone also decreases total and latent RNase activity,
but increase the free enzyme activity.
Pyridoxine/or pyridoxal phosphate in experiments in vivo or in vitro
increases the free alkaline ribonuclease activity; pyridoxine/or pyridoxal
phosphate decreases inhibitor-bound activity.
In the "in vivo" experimental condition vitamin B6 don?t modulates
the effect of dexamethasone but in "in vitro" experiments the effects of
dexamethasone are modulated by B6P ..
Key words: Alkaline ribonuclease, dexamethasone, pyridoxine,
pyridoxal phosphate, rat liver
UTICAJ PIRIDOKSINA NA AKTIVNOST ALKALNE
RIBONUKLEAZE JETRE PACOVA TRETIRANIH DEKSAMETAZONOM
Kratak sadržaj. Aktivnost alkalne ribonukleaze (pH 7,8) prisutna
je u brojnim ćelijama sisara u slobodnom obliku ili u spoju sa specifičnim
inhibitornim proteinom.
Nedavno je dokazano da piridoksal-5-fosfat, aktivna forma piridoksina,
interreaguje sa ?-amino grupama lizina u humanoj pankreasnoj ribonukleazi.
Istovremeno postoje dokazi da nuklearno vezivanje glukokortikoid-receptor
kompleksa može da se inhibiše piridoksal fosfatom.
Rezultati prikazani u našem radu ukazuju da tretiranje eksperimentalnih
životinja deksametazonom u trajanju od 7 dana izaziva smanjenje aktivnosti
alkalne ribonukleaze (ukupne,slobodne i latentne) u jetri pacova. U "in
vitro" eksperimentalnim uslovima deksametazon takođe smanjuje aktivnost
totalne i latentne alkalne ribonukleaze, ali povećava slobodnu aktivnost
enzima.
Piridoksin/ili piridoksal fosfat u "in vivo" ili "in vitro" eksperimentalnim
uslovima povećava aktivnost slobodne alkalne ribonukleaze; piridoksin /ili
piridoksal fosfat smanjuju inhibitorom-vezanu aktivnost,latentnu ribonukleazu.
U ekspeimentima "in vivo" vitamin B6 ne dovodi do promene efekata deksametazona,
ali u uslovima "in vitro" B6P modulira efekte deksametazona.
Ključne reči: Alkalna ribonukleaza, deksametazon, piridoksin,
piridoksal fosfat, jetra pacova
