Poly- containing nucleic acid bases

Synthesis of Poly-L-Lysine Containing Nucleic Acid Bases... 

Water soluble poly(ethyleneimine) derivatives containing nucleic acid bases were prepared by the method described in previous papers (Scheme... 

Interaction of the synthetic polymers and polynucleotides were estimated from the hypochromicity values in UV spectra. The UV spectra were measured with a JASCO UV-660 spectrometer equipped with a temperature controller at 20 C. Polynucleotides were obtained from Yamasa Shoyu Co. Ltd. Water soluble poly(ethyleneimine) derivatives containing nucleic acid bases and polynucleotides were dissolved in Kolthoff buffer (pH 7.0, O.IM KH2PO4 -0.05M Na2B40 -10H20). These solutions were stocked for 2 days at 20 C, and then mixed to give a polymer mixture of 10 total concentration of nucleic acid base units in aqueous solution. 

Natural and synthetic polynucleotides are known to form polymer complexes by specific base-base interactions between nucleic acid bases. The synthetic nucleic acid analogs such as poly (methacryamide), poly-(ethyleneimine) and poly(L-lysine) derivatives containing nucleic acid bases were also found to form polymer complexes with polynucleotides by specific base-base interactions. Since the solubilities of these nucleic acid analogs in water were low, the specific interactions should be studied in organic solvents or water-organic mixed solvents, such as dimethyl sulfoxide, ethylene glucol, and water-propylene glycol. 

The contents of the nucleic acid bases in the poly-L-lysine derivatives were determined by UV spectra of the polymers after hydrolysis The polymers were hydrolyzed in 6 N-hydrochloric acid at 105°C for 24 hr, into lysine dihydrochloride and the carboxyethyl derivatives of the nucleic acid bases. The quantitative calculation was made relative to the standard sample of the carboxyethyl derivative of the nucleic acid bases. The analytical data are listed in Table 1. It was found that the thymine and uracil derivatives was completely substituted to polylysine. Low value in case of adenine base in the polymer may be attributed to the unstability of the activated ester, Ade-PNP (2), and may also be explained in terms of the steric interaction among bulky pendant groups of the polymer. When the poly-L-lysine containing about 50 mol % adenine units was again treated with Ade-PNP, the adenine unit content in the polymer increased up to 74 mol %(,] ). 

Poly-L-lysine derivatives containing pendant nucleic acid bases were prepared by two different methods ... 

Water soluble nucleic acid analogs were prepared by grafting uracil, thymine, 5-fluorouracil, hypoxanthine, cytosine, and adenine derivatives containing a hydroxy group onto linear poly(ethyleneimine). These polymers contained about 90 unit% of the nucleic acid bases, and were easily soluble in water at neutral pH resign. The analogs were found to form complementary polymer complexes with each other and with polynucleotides. The interaction study was made on these polymers, and with polynucleotides poly(uridylic acid) poly(U), poly(adenylic acid) poly(A), poly(inosinic acid) poly(I) and poly(cytidylic acid) poly(C) in water. They were found to form polymer complexes with polynucleotide by specific base-base interaction in aqueous solution. 

Interactions between PEI-Hse-Hyp and poly(C) which contains the complimentary nucleic acid base can be clearly observed in aqueous solution at pH 7.0, as shown in Figure 3. The overall stoichiometry of the complex based on the nucleic acid base units was approximately 2 1 (hypoxanthine cytosine) under the conditions used. The maximum hypochromicity value (26%) was smaller than that of the poly (I) poly (C) (33%) system. 

Water soluble poly(ethyleneimine) derivatives containing both nucleic acid bases and homoserine units were prepared. The poly(ethyleneine) derivatives were found to form the 1 1 polymer complex by complementary base pairing in aqueous solution. These polymers also formed the polymer complexes with polynucleotides by specific interaction between complementary nucleic acid bases. 

The two types of natural polynucleotides (nucleic acids) are classified according to the sugars they contain. Ribonucleic acid (RNA) contains exclusively P-o-ribose, while the sugar in deoxyribonucleic acid (DNA) is P-2-deoxy-D-ribose. Different nucleic acids can have from around 80 nucleotides (nt), as in transfer RNA (tRNA), to over 10 nucleotide-pairs in a single eukaryotic chromosome. The unit for size of nucleic acid is the base (for single-stranded species) or the base-pair (bp, for double-stranded species), with the unit Kb (thousand base-pairs) and Mb (million base-pairs). Examples of synthetic homopolynucleotides are poly(uridylate) or poly(deoxyadenylate), in poly(U) or poly(dA)... 

A dipstick probe can be used to identify organisms in clinical or environmental specimens. It consists of adding a capture probe (containing a sequence of poly-dA or -dT bases that identifies it as a capture probe) coupled to dioxygenin as a reporter. Following destruction of unhybridized probe material, a dipstick that can hybridize with the capture probe base sequence is added. After all steps are completed, the presence of the capture probe is positive for the organism of interest. The theoretical sensitivity of a probe is < 1 pg of nucleic acid or 10 cells. However, by use of polymerase chain reaction (PCR), the DNA of a single cell can be amplified several millionfold. 

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