Bases pair formation

The mode of action has been a subject for research for a number of years. While it was originally thought that maleic hydrazide replaced uracil in the RNA sequence, it has been deterrnined that the molecule may be a pyrimidine or purine analogue and therefore base-pair formation is possible with uracil and thymine and there exists the probabiHty of base-pair formation with adenine however, if maleic hydrazide occurs in an in vivo system as the diketo species, then there remains the possibiHty of base-pairing with guanine (50). Whatever the mechanism, it is apparent that the inhibitory effects are the result of a shutdown of the de novo synthesis of protein. 

Fluorescence probes possessing the PyU base 46 selectively emit fluorescence only when the complementary base is adenine. In this case, the chromophore of is extruded to the outside of the duplex because of Watson-Crick base pair formation, and exposed to a highly polar aqueous phase. On the contrary, the duplex containing a PyU/N (N = G, C and T) mismatched base pair shows a structure in which the glycosyl bond of uridine is rotated to the syn conformation. In this conformation, the fluorophore is located at a hydrophobic site of the duplex. The control of base-specific fluorescence emission is based on the polarity change in the microenvironment where the fluorophore locates are dependent on the l>yU/A base-pair formation. 

Santamaria, R., and A. Vasquez. 1994. Structural and Electronic Property Changes of the Nucleic Acid Bases upon Base Pair Formation. J. Comp. Chem. 15,981. 

With AH -7 kcal/mol, a fairly typical value for base pair formation, and a melting temperature (where s l) of 80 C, Py is typically of order 10 or less (Figure 3). 

Applications in infrared spectroscopy A and B bands, iron-coordinated CO, 232, 186-187 application to allosteric mechanisms, 249, 566 bacteriorhodopsin, 246, 9, 380-381 caged compounds, 246, 6, 520-521 DNA [base pair formation, 246, 506 conformation, 246, 506-507 denaturation thermodynamics, 246, 506 ligand interactions, 246, 6, 507 sample requirements, 246, 506] fatty acyl ester determination in small cell samples, 233,... 

Base pair formation by hydrogen bonding seems also possible after the platination, as reflected by the appearance of iminoproton resonances. For the central GG sequence, these signals are only observed at low temperature, although shifted to lower field and broadened. 

The activation barrier for the slow phase and its average relaxation time suggest that we are observing base pair formation. The fact that the relaxation recorded at 1620 cm-1 is slightly faster than the relaxation at... 

AG° term can be determined from the knowledge of enthalpy and entropy of the base pair formation, A/ and A5 , using the usual equation ... 

Yanson et al. [41] using field-ionization mass spectrometry studied the formation of gas-phase GC, CC, AT and TT pairs. From measurements of temperature dependence of equilibrium constants, an interaction enthalpy for the base pair formation was derived. This technique was sometimes questioned because the determination of enthalpy from the slopes of appropriate van t Hoff curves might not be unambiguous. From Table 6 it is evident that the agreement with the present theoretical values is good, and concerns not only the relative interaction enthalpies but even the absolute values the average absolute error is less than 1.5 kcal/mol. 

Base-pair formation in mRNA is eliminated in any segment of the mRNA that is in contact with the ribosome. 

Figure 2836 Oxoguanine-adenine base pair. When guanine is oxidized to 8-oxoguanine, the damaged base can form a base pair with adenine through an edge of the base that does not normally participate in base-pair formation.

Ribonucleic acid is a class of polynucleotides, nearly all of which are involved in some aspect of protein synthesis. RNA molecules are synthesized in a process referred to as transcription. During transcription, new RNA molecules are produced by a mechanism similar to DNA synthesis, that is, through complementary base pair formation. The sequence of bases in RNA is therefore specified by the base sequence in one of the two strands in DNA. For example, the DNA sequence 5 -CC(1ATT ACG-3 is transcribed into the RNA sequence 3 -GGCUAAUGC-5. (Complementary DNA and RNA sequences are antiparallel.)... 

As opposed to classical E. coli DNA polymerases Pol I, Pol II, and Pol III core, Pol IV is devoid of any intrinsic 3 to 5 exonuclease (proofreading) activity (Wagner et al, 1999). This implies that the Pol IV fidelity is achieved solely by its capacity to discriminate between correct and incorrect base-pair formation. As shown in Fig. 2, Pol IV preferentially catalyses the incorporation of the correct nucleotides opposite all four template bases. 

Figure 25.19 (a) Base-pair formation by adenine and thymine and by cytosine and guanine, p) The double-helical strand of a DNA molecule held together by hydrogen bonds (and other intermolecular forces) between base pairs A-T and C-G. 

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