Inhibition of Precipitation

Inskeep and Bloom (1986) measured inhibition of calcite precipitation by organic ligands in simulated soil solutions prepared from CaCl2,KHC03 and seeds of CaCOs, and maintained at constant pH and CO2 pressure. The data fitted the rate equation  

Simultaneously, in all the soils the concentrations of P and dissolved organic carbon (DOC) in the soil solution increased as the pH increased, and this will have inhibited CaCOs precipitation. By analysing the combined data by multiple regression, Huang (1990) developed a rate equation for the three soils allowing for inhibition by P and DOC. The rate equation was developed from an earlier equation developed from studies in solution systems  

Interchange of Solntes between Solid, Liqnid and Gas Phases 

This sensitivity of precipitation in soil to organic ligands and other inhibitors explains why the soil solutions of submerged soils may be as much as a hundredfold over-satmated with respect to solid phases in the first few weeks following submergence (Chapter 4). 

---

The specificity of the antiserum raised against the Lea neoglycoprotein (9) was determined by hapten-inhibition studies using synthetic oligosaccharides,72 and derivatives of bovine and horse serum-albumin to which the Lea trisaccharide had been attached.73 On the basis of hapten inhibition of precipitation, this antiserum was shown to be highly specific for the carbohydrate portion of the synthetic antigen,... 

Figure 2. Immunochemical studies ofthe specificity ofrabbit antibodies elicited against Parp(al—3)D-Manp-BSA glycoconjugates (02). Top structures of the Salmonella O-antigen-specific saccharides used. Center Inhibition of precipitation in mixtures of anti-PM-BSA serum andS. paratyphi A PS. Key Center V, Octasaccharide S. paratyphi A. var. Durazzo ft.. Dodecasaccharide S. paratyphi A. var. Durazzo (II) , Parp D-Manp 4 OMe a., Parp -jpi- D-Manp O-0-NHCSNH(CH2)5COOH (VIII) m. Parp -j-i- D-Manp O-0-NHCOCF. (VII) U, Parp OMe A, Dodecasaccharide...

All data normalized to D-mannose = 1.0.4F rom Ref. 123 molarity required to produce 50% inhibition of precipitation of lentil lectin with phosphonomannan or glycoprotein. From Ref. 143 minimum amounts (mg/ml) completely inhibiting 4 hemagglutinating doses of lentil lectin, x, no inhibition at 20 mg/ml. "From Ref 213 millimolarity needed to produce 50% inhibition of agglutination. 

Sugar Minimum amount completely inhibiting 4 hemagglutinating doses (mg/ml) Amount giving 50% inhibition of precipitation (junoles)... 

At least part of the reason for these observations must be that precipitation is severely inhibited by organics such as humic acids (Berner et ai, 1978). Mitterer and co-authors (e.g., Mitterer and Cunningham, 1985) have explored the possible role of organic matter in cement formation. These authors suggested that, whereas some types of organic matter inhibit precipitation, other types, particularly those rich in aspartic acid, favor precipitation by complexing calcium. Inhibition of precipitation, coupled with slow transfer of fresh supersaturated seawater into sediment pores, seems to account for the lack of extensive early cementation. 

Ravichandran M., Aiken G. R., Ryan J. N., and Reddy M. M. (1999) Inhibition of precipitation and aggregation of metacinnabar (mercuric sulfide) by dissolved organic matter... 

Other proteins involved in the inhibition of precipitation have many tyrosine and proline residues. 

The first value was obtained by competition in equilibrium dialysis the second by inhibition of precipitation. 

Pauling, L. and Pressman, D. (1945) The serological properties of simple substances. IX. Hapten inhibition of precipitation of antisera homologous to the 0-, m-, and p-azophenylarsonic acid groups. J. Am. Chem. Soc., 67, 1003-1012. 

The carbohydrate-binding specificity of the lima bean lectin studied by inhibition of precipitation, and a sulfhydryl group protection assay [161], revealed the type A trisaccharide GalNAc(al-3)[L-Fuc(al-2)]Gal to be the best inhibitor, 40 times more potent than GalNAc. The a-glycosides of GalNAc are 8 times more potent than the corresponding 3-anomers. 

During the course of the investigation of precipitation reactions of polyhaptenic simple substances reported in the preceding paper of this series we found it desirable to cany out a study of the effects of changed conditions of precipitation and washing on the amount of residual precipitate. We also made some experiments on the inhibition of precipitation by added haptens, in order to see how great would be the effects of monohaptenic impurities possibly present in the substances studied. The results obtained are presented and discussed in this paper. 

The Inhibition of Precipitation by Hapten.— It was discovered by Landsteiner that a hapten... 

A number of experiments other than those reported in Table II were carried out in which varying amounts of purified antibody were added to a constant amount of antigen in a constant volume of solution. A 5 to 10% decrease in precipitated protein was noted at the largest amounts of antibody in every experiment. This effect of inhibition of precipitation by antibody excess is similar to but not nearly so marked as the effect in serum, in which a four-fold increase in amount of antiserum above the optimum was found to decrease the amount of precipitate to a third of the maximum value. 

I. INHIBITION OF PRECIPITATION BY HAPTENS AND CHEMICAL MODIFICATION AS PROBES FOR ANTIBODY SPECIFICITY... 

Fig. 2.2. Hapten inhibition of precipitation of rabbit antibodies to the p-azophenylar-sonate group. The precipitating antigen is ovalbumin-p-(p -phenylazo)-phenylarsonate. Inhibiting haptens are ortho-, meta-, and para-nitro derivatives of phenylarsonate. Approximately 770 /ag of precipitate formed in the absence of hapten. The data are from Pauling et al. (2).

The symbol C represents the concentration of peptide required for 50% inhibition of precipitation. When 50% inhibition was not achieved the percentage inhibition at maximal peptide concentration tested is given in parentheses. All amino acids are L. The N-terminus is at the left. 

In one set of experiments (27) a copolymer with the general structure shown in Fig. 2.5 was used to immunize rabbits. Antiserum was eventually obtained which precipitated the immunogen specifically. Precipitation could be inhibited by the random copolymer poly(Tyr,Glu). Maximum inhibition was obtained when the ratio of tyrosine to glutamic acid in the copolymer was 1.0 1.1. When the ratio in the copolymer was 1 4, only partial inhibition was possible, even with very high concentrations of the inhibitor, and no inhibition of precipitation was obtained when the ratio was 1 9 [a ratio widely different from that in the immunogen (Fig. 2.5, legend)]. 

---