Stereodifferentiation--the effect of P chirality of oligo(nucleoside phosphorothioates) on the activity of bacterial RNase H.
P stereoregular phosphorothioate analogs of pentadecamer 5'-d(AGATGTTTGAGCTCT)-3' were synthesized by the oxathiaphospholane method. Their diastereomeric purity was assigned by means of enzymatic degradation with nuclease P1 and, independently, with snake venom phosphodiesterase. DNA-RNA hybrids formed by phosphorothioate oligonucleotides (PS-oligos) with the corresponding complementary pentadecaribonucleotide were treated with bacterial RNase H. The DNA-RNA complex containing the PS-oligo of [all-RP] configuration was found to be more susceptible to RNase H-dependent degradation of the pentadecaribonucleotide compared with hybrids containing either the [all-SP] counterpart or the so called 'random mixture of diastereomers' of the pentadeca(nucleoside phosphorothioate). This stereodependence of RNase H action was also observed for a polyribonucleotide (475 nt) hybridized with these phosphorothioate oligonucleotides. The results of melting studies of PS-oligo-RNA hybrids allowed a rationalization of the observed stereodifferentiation in terms of the higher stability of heterodimers formed between oligoribonucleotides and [all-RP]-oligo(nucleoside phosphorothioates), compared with the less stable heterodimers formed with [all-SP]-oligo(nucleoside phosphorothioates) or the random mixture of diastereomers.
Koziolkiewicz
M
M
Polish Academy of Sciences, Department of Bioorganic Chemistry, Lódz, Poland.
Krakowiak
A
A
Kwinkowski
M
M
Boczkowska
M
M
Stec
W J
WJ
D001419:Bacteria / Q000378:metabolism; D001483:Base Sequence; D004789:Enzyme Activation; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D016914:Ribonuclease H / Q000378:metabolism*; D013237:Stereoisomerism
D009841:Oligonucleotides; D016914:Ribonuclease H