Enzymes RNAs functioning like

Some RNAs Function Like Enzymes Some RNAs Are Self-Splicing Some Ribonucleases Are RNAs Ribosomal RNA Catalyzes Peptide Bond Formation Catalytic RNA May Have Evolutionary Significance Inhibitors of RNA Metabolism... 

FRET is an extremely useful phenomenon when it comes to the analysis of molecular conformations and interactions. F or the analysis of interactions, in which two separate molecules are labeled with an appropriate pair of fluorophores, an interaction can be shown by observing FRET. Further, FRET can be used as a type of spectroscopic ruler to measure the closeness of interactions. Proteins, lipids, enzymes, DNA, and RNA can all be labeled and interactions documented. This general method can be applied not only to questions of cellular function like kinase dynamics [3] but also to disease pathways, for example, the APP-PS1 interaction that is important in Alzheimer s disease (AD) [4], Alternatively, two parts of a molecule of interest can be labeled with a donor and acceptor fluorophore. Using this technique, changes in protein conformation and differences between isoforms of proteins can be measured, as well as protein cleavage. 

Among the retroviruses " are types B and C oncoviruses which induce malignant tumors in mammals and birds and the human immunodeficiency virus (HIV), the apparent causative agent of AIDS. Their RNA functions in a surprising way. Each virion contains a reverse transcriptase, an enzyme that transcribes copies of circular dsDNA copies from the one or two mRNA-like molecules that make up the virus genome. Following action of the reverse transcriptase, one of the transcribed DNA circles becomes covalently spliced into the host s own cellular DNA. There it remains permanently as a provirus. RNA molecules transcribed from the provirus serve as mRNA for virus-encoded proteins and also as the genomes for new virus particles. 

Cerklewski and Forbes 1976). Also, excess zinc protects zinc-containing enzymes like ALAS, ferrochelatase, and ALAD. In vivo, aqueous solution containing zinc administered to rats significantly reduced the genotoxic effects induced by lead (Kowalska-Wochna et al. 1988). It was postulated that zinc s protective action may be related to its functioning in DNA and RNA polymerases and consequent enhancement of cell repair processes. 

RNA polymerase II represents a multi-enzyme complex of at least 12 proteins, but whose exact composition is difficult to determine. Hiis is due to the instabUity of the holo-complex, which makes the pmification and characterization of the enzyme difficult. Furthermore, it is likely that multiple forms of RNA polymerase II exist, each of slightly different composition and performing different functions. 

Like bacteria, eukaryotes have several types of DNA polymerases. Some have been linked to particular functions, such as the replication of mitochondrial DNA. The replication of nuclear chromosomes involves DNA polymerase a, in association with DNA polymerase S. DNA polymerase a is typically a multisubunit enzyme with similar structure and properties in all eukaryotic cells. One subunit has a primase activity, and the largest subunit (Afr -180,000) contains the polymerization activity. However, this polymerase has no proofreading 3 —>5 exonuclease activity, making it unsuitable for high-fidelity DNA replication. DNA polymerase a is believed to function only in the synthesis of short primers (containing either RNA or DNA) for Okazaki fragments on the lagging strand. These primers... 

There are 48 structural and cross-linking amino acids concerned with the shape of the protein but over half of the amino adds have functional groups sticking out of the chain—amino, hydroxy, acid groups, and the like. In fact, the enzyme uses only a few of these functional groups in the reaction it catalyses (the hydrolysis of RNA)—probably only two histidines and one lysine—but it is typical of enzymes that they have a vast array of functional groups available for chemical reactions. 

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