Open AccessThe Synthesis of the Alternating Copolymer Poly [r(A‐s 4 U)] by RNA Polymerase of Escherichia coli
Author(s) -
Cramer Friedrich,
Gottschalk Ellen M.,
Matzura Hans,
Scheit KarlHeinz,
Sternbach Hans
Publication year - 1971
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1971.tb01327.x
Subject(s) - hyperchromicity , rna polymerase , escherichia coli , enzyme , polynucleotide , chemistry , transcription (linguistics) , copolymer , polymerization , crystallography , microbiology and biotechnology , stereochemistry , biochemistry , biology , polymer , dna , gene , organic chemistry , linguistics , philosophy
The transcription of poly [d(A‐T)] by RNA polymerase from Escherichia coli in the presence of ATP and 4‐thiouridine triphosphate (s 4 UTP) lead to the synthesis of poly[r(A‐s 4 U)]. The investigation of the polymerisation kinetics furnished the kinetic parameter K m (ATP‐s 4 UTP) = 0.33 mM and V max (ATP‐s 4 UTP) = 204 nmoles AMP × mg enzyme −1 × min −1 . The structure of poly[r(A‐s 4 U)] was proved by nearest neighbour analysis and calculation of the AMP/s 4 UMP ratio from the absorption spectrum of poly[r(A‐s 4 U)]. As shown by sedimentation velocity analysis poly[r(A‐s 4 U)] exhibited a mean s 20, w value of 12 S. Enzymatic hydrolysis and thermal denaturation of poly[r(A‐s 4 U)] revealed the existence of a large hyperchromicity in the absorption spectrum. The absorption‐temperature profile of poly [r(A‐s 4 U)] measured at 0.08 M Na + showe a sharp cooperative transition with a T m of 52°C.