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Naturally Occurring Polymers—Animals
Published in Charles E. Carraher, Carraher's Polymer Chemistry, 2017
There are two different classes of chaperonins. Class I includes eukaryotic cells and class II includes certain prokaryotic cells. Eukaryotic cells have nuclei and include our cells. Prokaryotic cells do not contain nuclei and other organelles. We will focus on eukaryotic cells. Much of the information we have on chaperonins is derived from studying bacteria such as E. coli. The chaperonin in E. coli is given the designation GroES–GroEL. The GroEl is composed of two stacked seven-membered rings of 60 kDa mass that form a cylinder about 15 nm high and 14 nm wide, with a 5 nm central cavity capable of holding proteins to 60 kDa. GroES is a cochaperonin that acts as a dome or cap for one end of the GroEL portion. It is composed of a single seven-membered ring of about 10 kDa mass. Thus, much is known concerning the structures of at least a few of the molecules involved in the folding process. Much is also known concerning the function of these molecules, but this is beyond the present scope.
Metabolic Regulation in Response to Growth Environment
Published in Kazuyuki Shimizu, Metabolic Regulation and Metabolic Engineering for Biofuel and Biochemical Production, 2017
The organisms respond to a sudden temperature up-shift by increasing the synthesis of a set of proteins. This phenomenon is called as heat shock response, where this does not restrict to the temperature up-shift, but also other stresses such as solvent stress. The heat shock proteins play important roles in the assembly and disassembly of macromolecular complex such as GroE, for the intracellular transport such as Hsp70, for the transcription such as a70, for the proteolysis such as Lon, and for the translation such as lysyl tRNA synthetase. The heat shock response in E. coli is mediated by a32 encoded by rpoH. Among them, groEL, dnaK, and htpG encode major chaperones such as Hsp60, Hsp70, and Hsp90. ClpP, Lon, and HtrC are involved in the proteolysis. DnaK, DnaJ, GrpE, and RpoH are involved in the autoregulation of heat shock response. DnaK prevents the formation of inclusion bodies by reducing aggregation and promotion of proteolysis of misfolded proteins. A bichaperone system involving DnaK and ClpB mediates the solubilization or disaggregation of proteins. GroEL plays an important role for the protein transit between soluble and insoluble protein fractions, and participates positively in disaggregation and inclusion body formation. Small heat shock proteins such as IbpA and IbpB protect heat- denatured proteins from irreversible changes in association with inclusion bodies (Kitagawa et al. 2002, Sorensen and Mortenses 2005).
Photoinduced movement: how photoirradiation induced the movements of matter
Published in Science and Technology of Advanced Materials, 2022
Tetsuo Yamaguchi, Makoto Ogawa
GroEl, which is a tubular assembly of 14 identical protein subunits [171], incorporates denatured proteins and assists the refolding of the proteins in presence of adenosine triphosphate (ATP). ATP has a role in opening the cavity of GroEL to release the refolded protein. A cysteine at 231st in GroEL was functionalized with 4-carboxyl-AZ to control the release of incorporated proteins from GroEL [166,167]. Green fluorescence protein (GFP) was incorporated in the AZ functionalized GroEL in a tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) buffer. The release of GFP was monitored by fluorescence. The release of GFP from the AZ functionalized GroEL was initiated by the addition of ATP. The cis-AZ functionalized GroEL showed three times more efficient release of GFP than that from the trans-AZ functionalized GroEL, although unfunctionalized GroEL did not refold GFP. The difference in the accessibility of ATP to the trans- and cis-AZ functionalized GroELs was shown to affect the release of GFP.