Carboxylic Groups of Bovine Serum Albumin

Modification of Carboxylic Groups of Bovine Serum Albumin 

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Fig. 17. Titration data for the carboxyl groups of bovine serum albumin, at 25°C and ionic strengths 0.01 (lowest curve), 0.03, 0.08, and 0.15 (upper curve), plotted according to Eq. (14) (Tanford et al., 1955b).

Figure 17 shows an even more striking anomaly. It represents the titration of the carboxyl groups of bovine serum albumin (Tanford et al., 1955b), and it is seen that a constant value of w will not fit the data at all, the plots of pH — log[a /(l — a )] versus Z being curved. It should be noted however that the steepest parts of the plots (near Z = 0) are linear, and that the slopes give w values of 0.054, 0.036, 0.028, and 0.023, respec-... 

C. Modification of Carboxylic Groups of Bovine Serum Albumin... 

Fig. 23. Variation of pKobt with pH for the carboxyl groups of bovine serum albumin. Curve A, expected behavior [Eq. (II-17)] assuming w constant (0.023) and pK" 4.6 curve B, same as curve A except that w was assumed to vary slightly with pH according to the hydrodynamic behavior curve C, experimental curve of Tanford et al. (1955c) at ionic strength 0.15 (Loeb and Scheraga, 1956).

There are at least two explanations which can account for the abnormal ionization behavior of the carboxyl groups of bovine serum albumin either electrostatic effects or hydrogen bonding can give rise to such abnormalities. By attributing the abnormality to electrostatic effects, the slope of the pK vs. pH curve could be accounted for by a pH-dependent w factor however, this explanation cannot account for the magnitude of pK° (i.e., an observed pK° of 4.0 compared to the normal value of 4.6). Further,... 

Coupling of F(ab ) fragments to amino-groups on bovine serum albumin-cellulose acetate membranes using succinimidyl 4-(N-maleimidomethyl)-cyclohexane-1 -carboxylate, and attachment to platinum electrodes human IgG [6]... 

NOTE The carboxylic acid group of the hapten was coupled to bovine serum albumin... 

Figure 271 Canonized BSA is formed by the reaction of ethylene diamine with bovine serum albumin using the water-soluble carbodiimide EDC. Blocking of the carboxylate groups on the protein combined with the addition of terminal primary amines raises the pi of the molecule to highly basic values.

They experimented with four other proteins as carriers rabbit serum albumin, bovine serum albumin, bovine fibrinogen fraction I, and bovine )8-globulin fraction III. The structurally related derivatives of DDT and malathion, DDA, and 0,0-dimethyl S-carboxy-carboxyethyl phosphoro-dithioate (malathion half ester), respectively, were used as the specific haptens attached to these carrier proteins. These compounds contain free carboxyl groups, which when they reacted with thionylchloride, provide a means of coupling of the hapten to the amino groups of the protein carrier. 

To act as immunogens, PGs are covalently linked to an antigenic carrier. The chemical action selected must enable an adequate number of molecules to be bound to the carrier, and maintain the structural integrity of the molecule (except for the group involved in the covalent bond with the antigenic carrier). In our experiments, we used bovine serum albumin (BSA) as the carrier the free carboxyl function of the hapten, activated by a carbodi-imide, forms a peptide bond with the free NH2 groups of the antigenic carrier (8). Under our conditions (shov/n... 

In an interesting study on antibody-catalysed prodrug activation, the phosphonate 205 was prepared by Mitsunobu condensation of the phosphonic acid with the 3 -t2-Tbdms derivative of FdU. This hapten was linked to keyhole limpet hemocyanin and bovine serum albumin via the carboxylate group. The monoclonal antibodies specific for 205 were found to catalyse the hydrolysis of 5 -C -(/V-acetyl-D-valyl)-FdU, an FdU prodrug that was not hydrolysed by endogenous esterases, and a combination of 205 and antibody was as effective as FdU itself in preventing the growth of E.coli in vitro. ... 

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