Introduction of ω-carboxyl spacers onto cross-linked agarose gel beads by O-alkylation for the preparation of affinity adsorbents

Synthesis and characterization of quaternized agar in KOH/urea aqueous solution

Quaternized agar (QA) is synthesized in KOH/urea aqueous solution and shows low melting and gelling temperatures and antibacterial properties.

Molecular cloning and nucleotide sequence of Streptomyces griseus trypsin gene

Streptomyces griseus trypsin (E.C. 3.4.21.4) is one of the major extracellular proteinase, which is secreted by S. griseus. The gene encoding S. griseus trypsin was isolated from a S. griseus genomic library by using a synthetic oligonucleotide probe. Fragments containing the gene for S. griseus trypsin were characterized by hybridization and demonstration of proteolytic activity in S. lividans. Deduced amino acid sequence from the nucleotide sequence suggests that S. griseus trypsin is produced as a precursor, consisting of three portions; an amino-terminal pre sequence (32 amino acid residues), a pro sequence (4 residues), and the mature trypsin. The S. griseus trypsin consists of 223 amino acids with a computed molecular weight of 23,112. The existence of proline at the pro and mature junction suggests that the processing of S. griseus trypsin is non-autocatalytic.

Progress in affinophoresis

The use of polyionic polymers as mobile affinity matrices in electrophoresis has led to the development of a specific separation method for biological substances, affinophoresis. The conjugate of a polyionic polymer and an affinity ligand is called an affinophore. Electrophoresis of proteins in the presence of an affinophore results in a change in the mobility of a specific protein due to the difference between the mobility of the protein and that of the protein-affinophore complex. Polylysine is useful as a base polymer of affinophores and has been used successfully as an anionic matrix after succinylation. Affinophoresis of proteases, lectins and antibodies has been carried out in agarose gel and the mobility of the protein having affinity to each ligand was specifically changed. Two-dimensional affinophoresis, in which an affinophore was included only in the second-dimensional electrophoresis, was effective for the separation of the components of a complex mixture of proteins even if the change of mobility was not large. Red blood cells were successively treated with homologous antiserum, biotinylated second antibody, avidin and biotinylated succinylpolylysine as an affinophore. Specific acceleration of the homologous cells to the antiserum was observed even when the affinophoresis was applied to mixed red blood cells from different species.

Affinity gel titration: quantitative analysis of the binding equilibrium between immobilized protein and free ligand by a continuous titration procedure

A new method, called affinity gel titration, for analyzing the specific interaction between an immobilized protein and a ligand molecule is presented. Only one or two experimental runs permit the determination of not only the equilibrium constant but also the amount of immobilized protein. A suspension of the immobilized protein on agarose gel beads is confined in a constant volume mixing cell. A solution of a specific ligand molecule of constant concentration is introduced into the cell so that its concentration in the cell increases continuously (as in a mixing chamber for forming a convex gradient). The correlation between the concentration of the ligand in the efflux and the cumulative volume of the efflux can be analyzed either by regression to a theoretical curve or by a graphical method. Specific binding of p-aminobenzamidine to immobilized Streptomyces griseus trypsin was studied by this method. The dissociation constant and the amount of active trypsin were determined. The values obtained were in good agreement with the inhibition constant obtained by a kinetic experiment with free trypsin and with the amount of active site measured by using p-nitrophenyl p'-guanidinobenzoate, respectively. A single run of the titration procedure could be completed within 1 h.