caa a22 4500 475744543 CHVBK 20180406123509.0 cr unu---uuuuu 170329e20000701xx s 000 0 eng 10.1023/A:1026414928279 doi (NATIONALLICENCE)springer-10.1023/A:1026414928279 Binding Patterns and Kinetics of RNase A Interaction with RNA [Elektronische Daten] [Shahrokh Safarian, Ali Moosavi-Movahedi] Kinetics and binding studies of RNase A and its natural polymeric substrate (RNA), as well as the natural mixture of free 3′-ribonucleotides, were performed by difference spectrophotometry. The obtained kinetic saturation curve, with an anomalous nonhyperbolic shape and a distinct transition point, showed the interchange between the two conformational forms of the enzyme. This occurred in a narrow range of substrate concentration. At low substrate concentration, in spite of the existence of one catalytic cleft, RNase A behaves as a cooperative system, perhaps due to the interactions among the four cooperative binding subsites in the active cleft. At high substrate concentration, the conformational change did occur and was accompanied by a decrease in cooperativity and increment of the catalytic constant. The multiphasic shape of the binding curve, which, in the presence of the enzyme, produced 3′-ribonucleotides (as the ligand molecules), shows four binding subsites. The first three subsites are specific for the attachment of phosphate, ribose, and base moieties belonging to the first bound 3′-ribonucleotide in the direction of 3′-phosphate → ribose → base-5′. The fourth subsite relates to the second phosphate group of the second bound 3′-ribonucleotide. The binding direction also converts to 5′-phosphate → ribose → base-3′ for the ribonucleotide monomers in the RNA structure. Plenum Publishing Corporation, 2000 RNase A nationallicence RNA nationallicence 3′-ribonucleotides nationallicence kinetics and binding studies nationallicence binding subsites nationallicence binding pattern nationallicence Safarian Shahrokh Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran aut Moosavi-Movahedi Ali Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran aut Journal of Protein Chemistry Kluwer Academic Publishers-Plenum Publishers 19/5(2000-07-01), 335-344 0277-8033 19:5<335 2000 19 10930 https://doi.org/10.1023/A:1026414928279 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1026414928279 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Safarian Shahrokh Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran aut NATIONALLICENCE 700 1- Moosavi-Movahedi Ali Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran aut NATIONALLICENCE 773 0- Journal of Protein Chemistry Kluwer Academic Publishers-Plenum Publishers 19/5(2000-07-01), 335-344 0277-8033 19:5<335 2000 19 10930 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer