[Study of the substrate specificity of T4 RNA ligase: interaction of the enzyme with ATP analogs modified through the ribose residue and with affinity sorbents]. / Issledovanie substratnoi spetsifichnosti T4 RNK-ligazy: vzaimodeistvie fermenta s modifitsirovannymi po riboznomu ostatku analogami ATP i s affinnymi sorbentami.

To elucidate the role of the ribose moiety in substrate binding, various ATP derivatives modified in ribose moiety were studied as probes for the T4 RNA ligase first stage reaction. The kinetic parameters for competitive inhibition were determined. Inhibition experiments using substrate analogs demonstrated that the major binding determinants of ATP analogs were purine and triphosphate moieties of ATP; modification of the ribose moiety was not critical. Adenosine triphosphates attached to agarose were used as affinity adsorbent for purification of T4 RNA ligase. These derivatives had been successfully used in reversible binding of the enzyme. Best results were achieved with agarose coupled via N6 of the purine moiety of ATP.

[Isolation and some properties of polynucleotide phosphorylase from E. coli]. / Vydelenie polinukleotidfosforilazy iz E. coli i nekotorye ee svoistba.

A new method for isolation of polynucleotide phosphorylase from E. coli, including ion-exchange chromatography and gel-filtration has been developed. The method results in 300-fold purification of the enzyme, which being devoid of nuclease and phosphatase activities can further be utilized for oligonucleotide synthesis. It was shown that upon storage the enzyme loses the primer-independent activity and in the absence of NaCl can be used for further syntheses. An addition of NaCl stimulates the elongation of the oligonucleotide chain. Some advantages of polynucleotide phosphorylase from E. coli in comparison with the M. luteus enzyme are discussed.

[Purification and certain properties of pyruvate decarboxylase from bovine brain]. / Ochistka i nekotorye svoistva piruvatdekarboksilazy iz mozga byka.

A procedure of isolation and purification of pyruvate decarboxylase (PDC) from bovine brain is worked out. 350-fold purified enzyme preparation was homogenous under polyacrylamide gel electrophoresis. Molecular weight of PDC from bovine brain was estimated to be 180 000 by means of gel chromatography through Sephadex G-200. The protein was eluted in two peaks (with molecular weight of 180 000 and 90 000 respectively). After the treatment of the enzyme preparation with 6 M guanidine chloride. Probably, partial dissociation of the enzyme molecule into two subunits takes place in this case. Data on paper chromatography confirmed that highly purified PDC preparations from bovine brain were isolated as apoenzyme, since they were almost free of TPP.