Controlling the rate of organic reactions: rational design of allosteric Diels-Alderase ribozymes.

Allosteric mechanisms are widely used in nature to control the rates of enzymatic reactions, but little is known about RNA catalysts controlled by these principles. The only natural allosteric ribozyme reported to date catalyzes an RNA cleavage reaction, and so do almost all artificial systems. RNA has, however, been shown to accelerate a much wider range of chemical reactions.

Selection of a RNA aptamer that binds to human activated protein C and inhibits its protease function.

A high-affinity RNA aptamer to human activated protein C (APC) was selected from a pool of random sequences using in vitro selection. Activated protein C, a trypsin-like serine protease plays an important role along with thrombin as a regulator in blood clotting cascade. After seven rounds of selection and amplification, a single predominant nucleic acid sequence APC-167, a 167-base oligonucleotide with a random sequence core of 120 bases, was obtained.

Catalytic activities of hammerhead ribozymes with a triterpenoid linker instead of stem/loop II.

A minizyme is a hammerhead ribozyme with short oligonucleotide linkers instead of stem/loop II. In a previous study we demonstrated that a minizyme with high-level activity forms a dimeric structure with a common stem II (Amontov and Taira, J. Am.

Characterization of several kinds of dimer minizyme: simultaneous cleavage at two sites in HIV-1 tat mRNA by dimer minizymes.

A minizyme is a hammerhead ribozyme with short oligonucleotide linkers instead of stem-loop II. In a previous study we demonstrated that a minizyme with high activity forms a dimeric structure with a common stem II. Because of their dimeric structure, minizymes are potentially capable of cleaving a substrate at two different sites simultaneously.

Dependence on Mg2+ ions of the activities of dimeric hammerhead minizymes.

A minizyme is a hammerhead ribozyme with short oligonucleotide linkers instead of stem/loop II. In a previous study we demonstrated that a minizyme with high-level activity forms a dimeric structure with a common stem II [Amontov and Taira (1996) J. Am.