Unfolding pathway

Chen, B.-L., and King, J. (1991). Thermal unfolding pathway for the thermostable P22 tailspike endorhamnosidase. Biochemistry 30, 6260-6269. 

Oesterhelt F, Oesterhelt D, Pfeiffer M, Engel A, Gaub HE, Muller DJ. Unfolding pathways of individual bacteriorhodopsins. Science 2000 288 143-146. 

Cleavage of the polypeptide chain prior to partial reduction is an efficient way of controlling the reaction. For example, co-agatoxin IVB was completely reduced with TCEP, but upon treatment with trypsin, partially reduced species were detected under the same conditions 48 In contrast to these all or none characteristics in reduction, the four disulfide bonds of echistatin (1) can be reduced in a stepwise manner, which even allowed the elucidation of its reductive unfolding pathway 52 ... 

Oesterhelt et al.23 have reported unfolding pathways of individual wild type bR(w-bR) using AFM and DFS. A selection of typical unfolding profiles are shown in Figure 10-4 A (reproduced with permission from Oesterhelt et al.23)... 

Figure 10-6. Unfolding pathways of transmembrane -helices G and F. (a) Unfolding helices G and F in two steps, (b) Unfolding of helices G and F and their connecting loop in a three-step process, (c) Helices G and F and loop GF unfold in a four-step process, (d) Schematic drawing of the unfolding pathways of helices G and F and of loop FG.24...

Janovjk et al.25 have investigated the effect of temperature on the unfolding pathway. 

Figure 10-8. Upon exceeding an average pulling force of 80 17 pN, helix B and loop AB are unfolded (n = 31). (d) Helices C and B unfold in a three-step process. First, helix C unfolds at 108 26pN, thereby lengthening the stretched polypeptide to 158 aa (blue fit). Second, loop BC is pulled into the membrane at 116 33 pN (green fit). Third, helix B unfolds at pulling forces above 87 31 pN (n = 9). (e) Schematic drawing of the unfolding pathways found. The total number of force curves shown corresponds to 88...

Figure 10-12. Probability of unfolding pathways depends on temperature. The occurrence of main force peaks exhibiting no side peaks (solid lines) increased with increasing temperature. The probability of single structural elements, such as helices or loops, to unfold in a separate event decreases with increasing temperature...

Energy landscape of bacteriorhodopsin from AFM studies has been reviewed in this review. Recently we have embarked on a project to determine the unfolding pathway of bR mutants where mutations in F and G helices were introduced by site-directed mutagenesis,e.g. [E9Q/E194Q/E204Q] bR. This mutant was designed... 

Best RB, Fowler SB, Toca-Herrera JL, Clarke J (2002) A simple method for probing the mechanical unfolding pathway of proteins in detail. Proc. Natl. Acad. Sci. USA 99 12143—12148... 

Janovjak H, Kessler M, Oesterhelt D, Gubb G, Muller DJ (2003) Unfolding pathways of native bacteriorhodopsin depend on temperature. The EMBO J. 22 5220-5229... 

Cluster Analysis, Unfolding Pathway, and Transition State... 

Twenty MD unfolding trajectories were obtained at 498 K, i.e., 10 for the authentic protein and the remaining 10 for the recombinant protein [25]. Each trajectory was characterized by flows between different clusters of the MD structure ensemble. Such trajectory flows may thus represent the unfolding pathway. 

During the forward folding pathway the newly synthesized chain forms a partially folded single chain intermediate (5435). This folds further to a species with sufficient structure for chain recognition. Three of these intermediates associate into a protrimer in which the chains are associated but not fully folded (36). This species then folds further to the thermostable detergent and protease resistant native trimer. There are no known covalent modifications in the process. A similar process occurs in refolding urea denatured chains in vitro (37). Thermal Unfolding Pathway of Tailspike... 

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