GroEL structure

Seven GroES, 10,000 Da protein molecules, bind coincident with ATP binding at one end of the D7 GroEL structure to cap the structure and enclose a water-filled cavity of 175,000 A with the capacity to contain protein or peptide substrate inside of a size up to 70kDa. 

Figure 7.48. Stereo view of the aqueous chamber side of the GroES cap at the GroEL-GroES junction for the asymmetric (ADP)7-GroEL structure. The purpose is to estimate surface polarity by obtaining a sum over AGha for the face and to compare the value to the inner faces of GroEL as...

GroEL is a cylindrical structure with a central channel in which newly synthesized polypeptides bind... 

Enzymes assist formation of proper disulfide bonds during folding Isomerization of proline residues can be a rate-limiting step in protein folding Proteins can fold or unfold inside chaperonins GroEL is a cylindrical structure with a... 

Xu Z, Horwich AL, Sigler PB (1997) The crystal structure of the asymmetric GroEL-GroES-(ADP)7 chaperonin complex. Nature 388 741-750... 

A peptide of some 150 residues of GroEL (e.g., residues 191-345) folds stably into a monomer that is functionally active as a chaperone in vitro 97 Further, it can be covalently attached to agarose and other solid supports where the monodispersed fragment is extremely active as a chaperone.98 Crystal structures of recombinant minichaperones reveal that the active site is a flexible hydrophobic patch.99 It fits best to extended /3 strands. The basic function of GroEL is to provide a surface for binding exposed hydrophobic patches of denatured... 

The complex mechanism shown in Figure 19.23 summarizes these steps. In addition, some proteins may need to be sequestered inside the cage-like structure of GroEL, which can probably accommodate proteins up to 70 kDa.88 The... 

Chymotrypsinogen 480, 481 Chymotrypsin inhibitor 2 (CI2) folding kinetics 544-577, 577 GroEL binding 605 fragments 577, 578, 587, 588, 595 mechanism of folding 576-588 structure 576, 577 Circular dichroism (CD) 193-195 optimal absorbance for signal to noise 212-214... 

Figure 19.19 Reconstruction of the structure of GroEL from electron microscopy.

Sigler PB, Xu Z, Rye HS, Burston SG, Fenton WA, Horwich AL (1998) Structure and function in GroEL-mediated protein folding. Annu Rev Biochem 67 581-608 Silberman JD, Sogin ML, Leipe DD, Clark CG (1996) Human parasite finds taxonomic home. Nature 380 398... 

Only recently have heat shock proteins been used in the stabilization of nanoparticles. Aida et al. have demonstrated the inclusion of already preformed CdS nanoparticles within the chaperonin proteins of GroEL from Escherichia coli and T.th cpn from Thermus thermophilus HB8. These proteins were chosen as a result of sharing similar structural characteristics (1) tubular structure measuring 14.6nm in length, (2) cylindrical cavity with a 4.5-nm diameter, and (3) stability to adverse conditions (pH and temperature). T.th cpn, however, contains an additional bowl-shaped capping protein. 

Figure 11 Strategy for nanoparticle rnclusion/release by chaper-onin protein templates, (a) Structural representation of chaperonin proteins, GroEL, and T. th cpn. (b) Scheme depicting inclusion of CdS nanoparticles within chaperonin cavity and their triggered release from the cavity hy ATP. (Reproduced hy permission of Nature Puhlishing Group (www.nature.com))...

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