Saturation analysis

Ekins, R.P., Radioimmunoassay and saturation analysis. Basic principles and theory, Br. Med. Bull, 30, 3, 1974. 

Another problem associated with saturation analysis is that abnormally low results may be obtained unless cyanide is present when the vitamin is freed from its binder. It appears that forms other than cyanocobalamin are difficult to separate completely from the binding protein. Early studies that failed to recognize this not infrequently found that results from patients with pernicious anemia gave negative values (R9). A recent study by Brown et al. (B6) examined the effect of varying the concentration of cyanide used in the test. They found that an excess of cyanide resulted in a significant increase in apparent vitamin B12 levels in sera from patients who were deficient in the vitamin, but it had little effect on sera from normal patients. They found the mean of 12 vitamin B12-deficient sera to be 49 ng/liter when 3 mg/liter of cyanide was used in the extraction mixture, 104 ng/liter in the presence of 30 mg/liter of cyanide, and 196 ng/liter when 300 mg/liter of cyanide was used. The authors emphasized that cyanide was necessary to convert all of the several forms of vitamin B12 present in serum to cyanocobalamin but warned that the concentration should not be greater than 5 mg/liter. 

Zl. Zacharalds, R., Muir, M., and Chanarin, I., Comparison of serum vitamin B12 estimation by saturation analysis with intrinsic factor and with R-protein as binding agents. J. Clin. Pathol. 34, 357-360 (1981). 

Fig. 1. Assay for progestin receptors in human breast cancer cytosol. A. Saturation analysis. Total ( — ) and aspecific (o—o) binding are measured Specific binding (solid line) is calculated by subtraction. B. Scatchard plot derived from the binding data by the method of Chamness and McGuire [8]. Numerical data protein concentration of cytosol. 1.8 mg/ml assay volume, 100 /d cytosol volume, 50 /ul. Calculated values Kd = 0.76 nmol/l progestin receptor content, 510 fmol/mg protein.

SAR structure-activity relationship, sarcoma A malignant type of neoplasm, a cancerous growth, which arises in the connective tissue of skin etc. saturation analysis Where the amount of radioactivity... 

Dibenzoyl peroxide, CsHjCOOCCeHs. Mol. wt. 242.22, m.p. 107. Suppliers E, F, MCB. Commercial material can be purified by dissolving it in cold chloroform and adding methanol to the point of saturation. Analysis. ... 

The development of various EIA procedures has led to confusing terminology and classifications, which are often misleading concerning their fundamental features and tend to obscure their relative merits. Not surprisingly, many comparative studies produced inconclusive results. The frequent comparison of the relative merits of radioactive and enzyme labels, as evaluated in RIA by saturation analysis and in ELISA by immunometric analysis, is basically faulty since the underlying principles of these assays are different (Ekins, 1980). Here, EIA will be classified according to their essential differences to expose the inherent limitations and potentials of each assay EIA are based either on Activity Amplification (AA) or Activity Modulation (AM). 

The detectability of AM assays is not better than that of saturation analysis RIA, in contrast to AA assays. 

Sequential saturation analysis tion reaction can be formulated as ... 

A Zettner, PE Duly. Principles of competitive binding assays (saturation analysis) II. Sequential saturation. Chn Chem 20 5, 1974. 

AV Tembo, MA Schork, JG Wagner. Statistical survey of saturation analysis calibration curve data for prednisolone, prednisone and digoxin. Steroids 28 387,... 

HPLC is a method for the analysis and characterization of steroid receptors based on characteristics such as molecular weight. Qualitative relationships and multiple forms of the receptor can be maintained by the rapid gel-exclusion system, and contaminants can be readily identified (P2). Advantages of using HPLC include rapid analysis time, minimal receptor modification, improved resolution, and high reproducibility. Unfortunately the HPLC assay is tedious, requiring saturation analysis for each sample and quantitative validity has not been established for this procedure. Other disadvantages associated with HPLC methods include the requirement for expensive equipment and sophisticated technical skills. Therefore, HPLC analysis of receptor proteins is currently used only in research studies. 

G22, Cuardn, A., Determination of serum thyroxine by saturation analysis of thyroxine binding proteins. J. Nucl. Med. 10, 532-539 (1969). 

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