Chemical modifications, expressed proteins

The proteome is the set of expressed proteins at a given time under defined conditions it is dynamic and varies according to the cell type and functional state. One of the main differences when working with proteins is that there is not an amplification methodology for proteins comparable to PCR. Physical and chemical diversity of proteins are also higher than nucleic acids. They differ among individuals, cell types, and within the same cell depending on cell activity and state. In addition, there are hundreds of different types of post-translational modifications (PTMs), which evidently will influence chemical properties and functions of proteins. PTMs are key to the control and... 

The proteins produced by recombinant DNA technology are frequently accompanied by structural variants resulting from expression errors, in vivo modifications, posttranslational errors, improper folding, aggregation, and chemical modifications that occur during purification. The presence of vari-... 

Although the natural products of aromatic PKSs can be much more challenging to predict, their enzymes are much smaller and are often considered to be more tractable to routine heterologous expression, genetic modification and protein structure determination. Indeed, because large modular systems are so much more difficult to work with in vitro, much of what we now know about modular systems has been inferred from direct analogy to biochemical studies of aromatic systems. Aromatic PKSs can now be classified into several specialised families based upon both chemical product type and domain structure. Notably, NRPS analogues of the aromatic PKSs have not been observed. 

Chromatin is the complex combination of DNA, RNA and protein that makes up chromosomes inside the nuclei of eukaryotic cells it is divided between heterochromatin (condensed) and euchromatin (extended) forms. The functions of chromatin are to package DNA into a smaller volume to fit into the cell, to support the DNA to allow mitosis and meiosis, and to serve as a mechanism to control expression and DNA replication. Changes in chromatin strncture are affected by chemical modifications of histone proteins, such as methylation (DNA and proteins) and acetylation (proteins), and by non-histone DNA-binding proteins. Chromatin is easily visualised by staining, hence its name, which literally means coloured, lightened material. 

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