Physical and coding properties of poly(5-methoxyuridylic) acid.

The synthesis of poly(mo5U) requires a high concentration (2.7 mg/ml) of polynucleotide phosphorylase as well as a long reaction time (48 h). The resulting polynucleotide has a chain length of approximately 100 nucleotides. It shows no indication of a stable secondary structure. When poly(mo5U) is mixed with poly(A), a triple-stranded complex poly(A) . 2poly(mo5U) is formed. This complex has a melting temperature of 68.5 +/- 0.5 degrees C at 150 mMNa+ and exhibits a hysteresis loop between melting and reformation of the complex having a delta Tm of 11.5 degrees C. Poly-5-methoxyuridylic acid stimulates the binding of Phe-tRNA to 70-S ribosomes but is inactive in directing poly(Phe) synthesis.