A novel purification procedure for human alpha-fetoprotein by application of immobilised Cibacron Blue F3G-A as affinity ligand

Effects of specific binding reactions on the partitioning behavior of biomaterials

Affinity partitioning is a special branch of biomaterials separations using aqueous two-phase systems. It combines the capability of diverse biomolecules to partition in aqueous two-phase systems using the principle of biorecognition. As a result, the macromolecule exhibiting affinity for a certain ligand is transferred to that phase where the ligand is present. This chapter describes the present status of the theoretical background of this approach and the properties of various natural and artificial compounds which act as affinity ligands in liquid-liquid systems. The affinity partitioning of proteins (enzymes and plasma proteins), cell membranes, cells, and nucleic acids are described as typical examples. The results are discussed in terms of theoretical understanding and practical application.

Purification of canine alpha-fetoprotein and alpha- fetoprotein values in dogs

Canine alpha-fetoprotein (AFP) was purified by a two step method. Anti-dog AFP antiserum was produced by immunizing rabbits with canine fetal serum proteins that failed to bind to an anti-dog whole adult serum affinity column. Canine AFP was then purified from amniotic fluid using affinity chromatography with anti-dog AFP antiserum. The bound protein was then eluted and further purified by passage through an anti-dog whole adult serum column. The non-binding protein's purity and specificity was confirmed by immunoelectrophoresis, double-diffusion, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and cross-reactivity with anti-human AFP. The molecular weight of canine AFP was approximately 66,000 by SDS-PAGE. Normal adult dogs had serum AFP levels of 7-63 ng ml-1. Levels of AFP were not altered by pregnancy but did show a small peak 2 days following parturition. Newborn puppies had serum AFP levels of 14.08 +/- 5.94 mg ml-1 at birth. By 1 week of age, serum AFP had fallen to 0.766 +/- 0.758 mg ml-1. AFP values in newborn puppies are thus considerably higher than those previously reported in humans, pigs and cattle.

Chromatography of human immunoglobulin G on immobilized drimarene rubine R/K-5BL. Study of mild, efficient elution procedures

A range of substances were screened to find eluents for human immunoglobulin G (IgG) which are retained with a strong affinity by immobilized Drimarene Rubine R/K-5BL. The strong affinity of IgG for the dye is partly due to the presence of copper in the dye. This was suggested by the effect of substances able to make coordination bonds with metals that elute the IgG and also the effect of metal stripping from the immobilized dye. Several mobile phase conditions were found that allowed desorption of retained IgG on immobilized Drimarene Rubine R/K-5BL without using a protein denaturant. A procedure was also devised for separating IgG2 from other IgG subclasses using chromatography on immobilized Rubine R/K-5BL and column development with an AMP gradient.

Human alpha-fetoprotein (AFP) causes a selective down regulation of monocyte MHC class II molecules without altering other induced or noninduced monocyte markers or functions in monocytoid cell lines

Human alpha-fetoprotein (AFP) purified from human amniotic fluid was investigated for its effect on human monocytoid cell lines, including U 937 cells with established subclones. The impact of AFP on the expression of surface markers (MHC class I and II, CD4, CD18, CD45, Fc receptors for IgG) was analyzed using known inducers of monocyte-macrophage differentiation such as phorbol esters and IFN-gamma. Furthermore we investigated the effect of AFP on the induction of macrophage antibody-dependent cell-mediated cytolytic activity (ADCC). AFP did selectively induce a rapid down regulation of surface MHC class II expression. No evidence of alterations was found in the endogenous or differentiation-induced expression of other markers on the surface on monocytes, nor did AFP affect the functional maturation of surface Fc receptors or the ability to express ADCC.

Chemistry and biology of alpha-fetoprotein

Alpha-Fetoprotein (AFP) is a product of specific fetal tissues and of neoplastic cells of hepatocyte or germ cell origin in adults. This protein belongs to a gene family that is phylogenetically most closely related to serum albumin. Its primary, secondary, and tertiary structural aspects appear similar to the three-domain concept proposed for the latter protein. The primary sequence of AFP departs most widely from serum albumin in the first 135 amino acid residues, with about 42% of the remaining 590 residues of the human proteins being identical. Some evidence exists that there are limited sequence differences in the AFP of a given animal species. AFP shows considerable charge heterogeneity that appears to relate mostly to its glycoid moiety. The proteins of some species such as the rat show more pronounced heterogeneities than that of humans. The variations in extent and type of glycosylations are evidenced by differences in the binding to various lectins. These interactions are being extensively explored in attempts to differentiate the sources of the protein produced by various normal and neoplastic cells and may provide valuable diagnostic methods. AFP, like serum albumin, shows relatively strong binding affinities for a variety of ligands. The most notable difference is the strong preferential binding of polyunsaturated fatty acids by AFP. This protein may play a role in transporting these substances to developing and to malignant cells. Various agents affect the synthesis of this protein both by specific fetal tissues and by neoplastic cells. Marked differences in the responses of cells, particularly those of neoplastic types, are indicative of variations in the genetic factors responsible for control of its synthesis. The subject of the genomic repression of the synthesis of AFP seen in fetal life upon maturation of the liver and the reoccurrence of synthesis upon malignant conversion of hepatocytes and of certain germ cells are of particular interest. The regulation of the closely related AFP and albumin genes is providing a powerful and attractive model to examine molecular events in the activation and inactivation of specific genes during development and in oncogenic processes. Extensive measurements of AFP during pregnancy and in the course of neoplasias, notably hepatoma, are being made to aid in following changes in such developments. Various specific physiological roles for this protein are also being proposed. One of these is its possible action in the regulation of immune processes.(ABSTRACT TRUNCATED AT 400 WORDS)

The use of dye-ligand affinity chromatography for the purification of non-enzymatic human plasma proteins

Literature data are analysed in this review on the use of immobilized triazine dyes for the characterization, isolation and purification of non-enzymatic human plasma proteins in both conventional and high-pressure liquid chromatography systems. Attention is focused on the mode of interaction between the dyes and these proteins, as well as on the advantages over previously reported techniques. Future developments are discussed.

Affinity chromatography and affinity partition of human serum pre-albumin using immobilized Remazol Yellow GGL. Evidence that albumin increases binding of pre-albumin to the dye

Pre-albumin was isolated from human serum or plasma by ammonium sulphate fractionation and by chromatography on dye-substituted Sephadex G-100 to a high degree of purity. The interaction of the pre-albumin with the dye Remazol Yellow GGL was studied in more detail by means of affinity partitioning in an aqueous two-phase system composed of dextran and poly(ethylene glycol). In the presence of dye-substituted poly(ethylene glycol) the partition coefficient of pre-albumin increases, indicating an interaction with the dye. Human serum albumin was found to enhance this interaction considerably. A similar effect was also shown by bovine albumin but not by egg albumin.

Affinity partitioning of albumin and alpha-fetoprotein in an aqueous two-phase system using poly(ethylene glycol)-bound triazine dyes

Human albumin and alpha-fetoprotein are partitioned in an aqueous two-phase system composed of 10% (w/w) Dextran and 7.5% (w/w) poly(ethylene glycol). When a small amount of poly(ethylene glycol) is replaced by Cibacron Blue F3G-A-liganded poly(ethylene glycol) the partition coefficient, K, of albumin increases by the factor of about 4000 whereas the K value of alpha-fetoprotein undergoes only a small change. The change of the partition coefficient in a logarithmic scale induced by increasing dye-polymer concentrations turned out as a useful measure for the affinity of albumin and alpha-fetoprotein to the dyes. The effect of pH and salt concentration on the affinity partition of albumin and alpha-fetoprotein is demonstrated. The partition of the two proteins in presence of Cibacron Blue F3G-A-liganded poly(ethylene glycol) is compared with seven other triazine dye-poly(ethylene glycol) derivatives.