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The high resolution proton nuclear magnetic resonance (NMR) spectra of the synthetic DNA block polymer d(C15A15)-d(T15G15) were studied in order to more completely understand telestability in DNA, and to provide fundamental NMR data on DNA helices and random coils. Spectra were measured in the spectral region from 0 to 15 ppm downfield from the usual standard, sodium 4,4-dimethyl-4-silapentane-1-sulfonate(DSS), at various temperatures (24-98 degrees C) in solution containing either moderate or high ionic strength. The effect of actinomycin binding to the block polymer also was studied. The major conclusions derived from this study are as follows: (1) The majority of base pairs in the AT helix of the block polymer have the same conformation as in d(A)n-d(T)25 and d(A)21-d(T)21. (2) The conformation of the GC helix in the block polymer is different from the AT helix and this perturbs the conformation of three or four A-T base pairs at the junction of the AT-GC helix. (3) The conformation of the AT helix is unaffected by salt over the range examined (approximately 0.04 - approximately 2 M), but the conformation of the GC helix changes. (4) There are subtle changes in the conformation of the AT helix as the temperature is increased and resonances characteristic of the random coil and the double-helical state can be simultaneously observed. (5) Binding of actinomycin, which is specific for the GC helix, induces quite large (over 1 ppm) upfield shifts of the resonances from the GC base pairs. This is consistent with an intercalation model in which actinomycin D (Am) is assymetrically sandwiched between two GC base pairs in such a manner that overlap with the guanosine residues is greater than with the neighboring cytidines. (6) The presence of the drug may also perturb A-T base pairs located near the AT-GC junction, but it has no effect on the majority of the AT pairs. However, as expected, Am elevated the Tm of the AT helix, even though it binds to the other end of the DNA.

We have developed a chemiluminescent immunoenzymometric system. The first commercial application of this chemiluminescent assay (CLA) is the measurement of total IgE and allergen-specific IgE in human serum. The CLA system is a second-generation adaptation of the MAST RIA allergy profiling system. The MAST CLA system assay protocol consists of three steps: overnight incubation of serum, a 4-h incubation with enzyme-labeled antibody, and a 30-min chemiluminescent reaction, which produces a visible image (immunograph) on high-speed Polaroid instant film. The densities of the bands produced on the film are quantified with an inexpensive microprocessor-controlled infrared transmittance densitometer. The novel luminogenic substrates used yield a constant light output for over 2 h with an intensity at least 10-fold greater than that of commercial chemiluminescent reagents. The MAST CLA system exhibits sensitivity, specificity, and precision equal to that of the MAST RIA system (r = 0.96 for 40 serum samples analyzed with 25 allergens). As many as 35 different allergens per sample can be quantified in a single assay. The MAST CLA system requires no standard curve or volume-dependent pipetting steps, incorporates both positive and negative controls for each sample, and quantifies allergen-specific IgE at picomolar concentrations.

Abbreviations: (AGE) advanced glycation end product, (IR) infrared, (DFA) 1-deoxyfructosyl glycation adduct, (LED) light-emitting diode, (UV) ultraviolet Keywords: advanced glycation end products, biomicroscope, diabetes mellitus, fluorescence ratio, lens autofluorescence