Melting studies on spin-labeled polyadenylic–polyuridylic complexes

✍ Scribed by Yu-Ching E. Pan; Albert M. Bobst

• Publisher: Wiley (John Wiley & Sons)
• Year: 1973
• Tongue: English
• Weight: 280 KB
• Volume: 12
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1973.360120213

✦ Synopsis

Abstract

Temperature‐dependent conformational transitions of spin‐labeled poly rA, spin‐labeled poly rU and the two‐stranded helical complexes consisting either of spin‐labeled rA·poly rU or spin‐labeled poly rU·poly rA have been measured by electron spin resonance spectrocopy. The polynucleotides were spin labeled with 4‐(2‐iodoacetamido)2,2,6,6‐tetramethylpiperidinooxyl and the spin label to nucleotide base ratio was approximately 1:600. The relationship between the log of tumbling time τ and the reciprocal absolute temperature for the spin‐labeled single and double‐stranded polynucleotides is presented. An agreement between T~m~^OD^ (optical density melting) and T~m~^sp^ (spin melting) is found for the complexes, which strongly supports the conclusion that the same temperature‐dependent structural changes are monitored with both techniques.