Hybrid selection procedures

A number of functional studies have shown that the partially ligated species and valency hybrid Hbs exhibit slowly interconverting conformation states. Some of them have properties that are intermediate between those associated with the T- and R-quaternary conformations (Cassoly and Gibson, 1972 Samaja et al., 1987 Sharma, 1989 Berjis et al., 1990). Thus, one needs to be careful in making correlations between a given crystal structure of a specific Hb species and its functional properties. It should be kept in mind that crystallization is a selective procedure, i.e., it selects those proteins with specific structures that are crystallizable under a given set of crystallization conditions. The structures of these crystallized proteins may not be the dominant ones when function is measured under solution conditions different from those used in crystallizing the proteins. 

As shown in figure 2, skin-derived fibroblasts serve reliably as standards for prenatal diagnosis of severe or partial HG-PRT deficiencies. The heteropolykaryon test has principal advantages compared to the more conventional macro-technique with hybrid cell strains isolated by selective procedures ... 

For monoclonal antibodies, inbred rats were immunized with post-Mono Q receptor. Fusions and hybrid myeloma selection procedures were based on those of Galfre and Milstein [2]. Initial screening of culture supernatants was by ELISA using pure receptor. Strong positives were further screened by immunoblotting against post-DEAE receptor after SDS-PAGE. 

Colombatti, M., Nabholz, M., Gros, O., and Brown, C. (1983) Selective killing of target cells by anti-body-ricin A-chain or antibody-gelonin hybrid molecules Comparison of cytotoxic potency and use in immunoselection procedures./. Immunol. 131, 3091. 

Various novel imprinting techniques have also been presented recently. For instance, latex particles surfaces were imprinted with a cholesterol derivative in a core-shell emulsion polymerization. This was performed in a two-step procedure starting with polymerizing DVB over a polystyrene core followed by a second polymerization with a vinyl surfactant and a surfactant/cholesterol-hybrid molecule as monomer and template, respectively. The submicrometer particles did bind cholesterol in a mixture of 2-propanol (60%) and water [134]. Also new is a technique for the orientated immobilization of templates on silica surfaces [ 135]. Molecular imprinting was performed in this case by generating a polymer covering the silica as well as templates. This step was followed by the dissolution of the silica support with hydrofluoric acid. Theophylline selective MIP were obtained. 

Acridinium ester—labeled chemiluminescent probes have been utilized to detect the specific protein-coding transcripts and to distinguish between transcripts that code for the 190-kDa protein and the two closely related 210-kDa proteins. The assay is called the hybridization protection assay (D3). In this assay, RNA isolated from the patient s white blood cells is first amplified by PCR. The amplified product is incubated with the chemiluminescent probe. The unhybridized probe is removed by selective hydrolysis in sodium tetraborate buffer, containing surfactant Triton X-100 at pH 8.5, in an incubation step at 60°C for 6 min. After the sample is cooled to room temperature, the chemiluminescence of the hybridized probe is measured in a luminometer. The procedure is reported to detect one leukemic cell in a population of a million or more normal cells. It is also rapid, requiring less than 30 min. Its reliability has been attested to by correlation with results obtained on karyotypic and Southern blot analysis (D3). 

Screen selected colonies for desired DNA fragment. In one procedure a small sample from each of the selected colonies is placed onto spots on a nitrocellulose filter. Several colonies can be placed on one filter and the bacteria lysed, hybridized with a radio-... 

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