Ribonucleic acid ribozyme

Enzymes are biological catalysts—i. e substances of biological origin that accelerate chemical reactions (see p. 24). The orderly course of metabolic processes is only possible because each cell is equipped with its own genetically determined set of enzymes. It is only this that allows coordinated sequences of reactions (metabolic pathways see p. 112). Enzymes are also involved in many regulatory mechanisms that allow the metabolism to adapt to changing conditions (see p.ll4). Almost all enzymes are proteins. However, there are also catalytically active ribonucleic acids, the ribozymes" (see pp. 246, 252). 

Enzymatically active ribonucleic acid segments (some of which are known as ribozymes) with the capacity to catalyze RNA self-splicing or peptide bond formation. The overall catalytic rate enhancement is around 10 ... 

Ribozymes are RNA molecules with catalytic activity (ribo- like ribonucleic acid, -zyme like enzyme). Despite having only four different chemical... 

Enzymes are biological catalysts, all of which are proteins, except for a class of RNA-modifying catalysts known as ribozymes ribozymes are molecules of ribonucleic acid that catalyse reactions on the phosphodiester bond of other RNAs. The International Union of Biochemistry and Molecular Biology have developed a nomenclature for enzymes, the EC numbers each enzyme is described by a sequence of one of four numbers preceded by EC . The first number broadly classifies the enzyme based on its mechanism. 

All enzymes are proteins, with the exception of the recently discovered ribozymes. Ribozymes are special ribonucleic acids performing catalytic functions in the processing of RNA which will not be considered here. Proteins are polar macromolecules with molecular mass in the range 104-106. They are linear polymers, defined by the sequence of amino acids, which are linked by peptide bonds ... 

Although enzymes are considered to be proteins, enzyme activity has recently been found in ribonucleic acid (RNA) in certain organisms. These ribozymes may yield clues to the origins of life on Earth. DNA needs... 

In recent years, the traditional definition of biocatalysts with enzymes that are proteins having catalytic functions in biological systems was expanded to a point where a series of ribonucleic acids, called ribozymes, also acts as a biocatalyst. Much effort was devoted to developing artificial ribozymes as well. In such approaches a combination of strategies to mimic ribonucleases and to simulate complementary molecular recognition of nucleic acids is essential. 

Higher order structures are necessary to understand the function of ribozymes (ribonucleic acid enzymes). Ribozymes function in diverse ways, from hydrol5ftic reactions in cleaving nucleic acids to peptidyl-transferase activity in building proteins. How the ribozyme folds into its 3-D structure determines which caXaXytic sites such as metal ions and hydroxyl residues are available [8]. Though a wide array of RNAs are undergoing clinical trials for therapeutic applications (for a review, see [9]), a cited clinical study showed favorable results for a therapeutic ribozyme [10]. 

Enzymes, as you probably know, are proteins that can make chemical reactions happen in a more selective and faster way. At the end of each reaction cycle the enzymes remain unchanged so they act as catalysts. Since they occur in the living world we call them biocatalysts. Aside from proteins, ribonucleic acids and their fragments can act as catalysts and are called ribozymes, by analogy to enzymes. Enzymes are extracted from living tissues, for example, milk, saliva, liver, muscle have to be stored under carefully maintained conditions and, once outside living tissue, lose their activity fast. Isolation and purification of enzymes and assaying their activity have been major operations in biochemical and biomedical laboratories. Today,... 

Ribozyme (Section 25.5B) A ribonucleic acid that acts as a reaction catalyst. 

In cellular biological organisms nearly all chemical reactions are catalyzed by enzymes. For example, the enzyme urease catalyzes the hydrolysis of urea and the enzyme protease catalyzes the hydrolysis of proteins. Most enzymes are proteins, although some ribonucleic acids have been found to exhibit catalytic activity and have been called ribozymes. Ribozymes usually catalyze the combination of other RNA fragments, and require the presence of divalent metal ions such as Mg +. It has been thought that divalent metal ions were necessary to the function of ribozymes, but... 

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