Premium
Oligomeric hepatoproliferin disaggregates into an active monomer that was purified and forcefully dissociated into two different ionic species
Author(s) -
Oosthuizen Mathys M.J.,
Lambrechts Hugo
Publication year - 2006
Publication title -
biofactors
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.204
H-Index - 94
eISSN - 1872-8081
pISSN - 0951-6433
DOI - 10.1002/biof.5520280106
Subject(s) - chemistry , cationic polymerization , monomer , amine gas treating , ammonium , ionic bonding , counterion , homogeneous , ionic strength , bicarbonate , molecular mass , ammonium bicarbonate , chromatography , incubation , cytosol , ion , polymer chemistry , organic chemistry , biochemistry , enzyme , aqueous solution , polymer , raw material , physics , thermodynamics
Hepatoproliferin (HPF), a liver regeneration factor, was isolated initially as an aggregated molecule (big‐HPF) and was purified into two homogeneous, bioactive species of 14 kDa and 18.5 kDa. These two big‐HPFs were disaggregated to completion into two monomeric forms (small‐HPFs) when incubated for 10 days in 0.15 M ammonium bicarbonate at 25°C. Both monomeric forms were purified to homogeneity as active entities, one with a molecular mass of 944 Da and one with a molecular mass of 1066 Da. Each of the two 35 S‐labelled small‐HPFs was found, by enzymic analysis, to contain a charged sulfonated saccharide, which was neutralized by a specific amine. Monomeric HPF is therefore a stable ionic complex formed between these two ionic species. So strong was the electrostatic association that small‐HPF remained intact in solution and no amine was displaced by the ammonium ions of the buffer. Small‐HPF remained unimpaired during purification, since all activity was retained despite alternating acidic and basic conditions. However, when small‐HPF was brought into contact with either a cationic or an anionic resin, it was dissociated to completion when mixed continuously with the resin for 4 days. The ionic entity that was released had no bio‐activity and was either a pure radioactively labeled saccharide or a non‐labeled amine, depending on the kind of resin used. When incubated together, the separated counterions combine to regain full activity after 2 days of reassociation. However, with incubation for longer, this reassociated small‐HPF formed different oligomeric HPFs by aggregation. Small‐HPF is therefore a new kind of growth enhancer, consisting of an acidic sulfonated saccharide and a basic amine assembled into a stable active ionic complex that has a tendency to aggregate.