R. Selvam et Vp. Lakshmi, OCCURRENCE OF HISTONE-RELATED OXALATE BINDING IN RAT-LIVER NUCLEUS, Molecular and cellular biochemistry, 156(2), 1996, pp. 93-100
The rat liver nuclear oxalate binding protein was isolated, purified b
y anion and cation exchange column chromatography using Diethyl Amino
Ethyl Sephadex, Carboxy Methyl Cellulose and Carboxy Methyl Sephadex C
-50 ion exchangers. The purified oxalate binding protein was found to
be H1B of H1 fraction of histones. Kinetic analysis of oxalate binding
showed the presence of two affinity sites, one with Kd of 133.5 nM an
d Bmax of 40 pmoles and another with Kd of 262.5 nM and Bmax of 210 pm
oles. The optimal oxalate binding was at pH 4.2 and at 28 degrees C. T
he oxalate binding was specific and reversible and not due to ionic ch
arge interaction. The IC50 of other dicarboxylates was higher than tha
t of oxalate. EGTA had no effect on oxalate binding but di- and tri-ca
rboxylate carrier inhibitors and thiol modifying agents significantly
lowered the binding activity. Oxalate binding to histones was signific
antly reduced in the presence of DNA or nucleotides, but RNA had no ef
fect. ATP completely inhibited the oxalate binding activity at 1 mM co
ncentration. Different tissues exhibited oxalate binding showing ubiqu
itous nature. Calf thymus H1 showed maximal binding similar to liver h
istones.