Biomaterial Database

Cryoenzymology of the hammerhead ribozyme. 1998

A L Feig, and G E Ammons, and O C Uhlenbeck

Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309, USA.

The technique of cryoenzymology has been applied to the hammerhead ribozyme in an attempt to uncover a structural rearrangement step prior to cleavage. Several cryosolvents were tested and 40% (v/v) methanol in water was found to perturb the system only minimally. This solvent allowed the measurement of ribozyme activity between 30 and -33 degrees C. Eyring plots are linear down to -27 degrees C, but a drastic reduction in activity occurs below this temperature. However, even at extremely low temperatures, the rate is still quite pH dependent, suggesting that the chemical step rather than a structural rearrangement is still rate-limiting. The nonlinearity of the Eyring plot may be the result of a transition to a cold-denatured state or a glassed state.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D009843	Oligoribonucleotides	A group of ribonucleotides (up to 12) in which the phosphate residues of each ribonucleotide act as bridges in forming diester linkages between the ribose moieties.
D003080	Cold Temperature	An absence of warmth or heat or a temperature notably below an accustomed norm.	Cold,Cold Temperatures,Temperature, Cold,Temperatures, Cold
D003451	Cryoprotective Agents	Substances that provide protection against the harmful effects of freezing temperatures.	Cryoprotective Agent,Cryoprotective Effect,Cryoprotective Effects,Agent, Cryoprotective,Agents, Cryoprotective,Effect, Cryoprotective,Effects, Cryoprotective
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000432	Methanol	A colorless, flammable liquid used in the manufacture of FORMALDEHYDE and ACETIC ACID, in chemical synthesis, antifreeze, and as a solvent. Ingestion of methanol is toxic and may cause blindness.	Alcohol, Methyl,Carbinol,Sodium Methoxide,Wood Alcohol,Alcohol, Wood,Methoxide, Sodium,Methyl Alcohol
D016337	RNA, Catalytic	RNA that has catalytic activity. The catalytic RNA sequence folds to form a complex surface that can function as an enzyme in reactions with itself and other molecules. It may function even in the absence of protein. There are numerous examples of RNA species that are acted upon by catalytic RNA, however the scope of this enzyme class is not limited to a particular type of substrate.	Catalytic RNA,Ribozyme,Ribozymes