PRELIMINARY PURIFICATION AND PARTIAL CHARACTERIZATION STUDIES OF A LOW-MOLECULAR-WEIGHT CYTOSOLIC LEAD-BINDING PROTEIN IN LIVER OF THE CHANNEL CATFISH (ICTALURUS-PUNCTATUS)

The present study reports the isolation and partial characterization o f a lead-binding protein (PbBP) in the liver of the channel catfish (I ctalurus punctatus). The protein has a molecular weight of 10 kDa as d etermined by SDS polyacrylamide gel electrophoresis and contains relat ively large amounts of glycine (18.3%), aspartic acid (10.2%) and seri ne (15.1%). Western blot studies conducted using polyclonal antibodies to the rat renal PbBP and metallothionein (MT) showed no cross-reacti vity, suggesting that the fish hepatic protein is immunologically dist inct from these low-molecular weight metal-binding proteins in mammals .