Aggregation, of peptides

Catalytic hydrolysis of ester was achieved on the snrface of nanofibers formed by the aggregation of peptide-alkyl chain amphiphiles. The esterase activity was determined using 2,4-dinitrophenylacetate (DNPA) as model substrate, and histidine residues were incorporated within the peptide backbone of the amphiphiles to mimic esterase properties. The high density of the reactive sites displayed on the surface of the self-assemblies, together with their high internal order, considerably increases the hydrolysis rate of these catalytic particles compared to catalysts in solution and in spherical aggregates, which should have less order (Figure 13)." ... 

Lee JJ, Albrecht M, Rice CA, Suhm MA (2013) Adaptive aggregation of peptide model systems. J Phys Chem A 117 7050... 

Conformational free energy simulations are being widely used in modeling of complex molecular systems [1]. Recent examples of applications include study of torsions in n-butane [2] and peptide sidechains [3, 4], as well as aggregation of methane [5] and a helix bundle protein in water [6]. Calculating free energy differences between molecular states is valuable because they are observable thermodynamic quantities, related to equilibrium constants and... 

The most recent advance in treating HIV infections has been to simultaneously attack the virus on a second front using a protease inhibitor. Recall from Section 27.10 that proteases are enzymes that catalyze the hydrolysis of proteins at specific points. When HIV uses a cell s DNA to synthesize its own proteins, the initial product is a long polypeptide that contains several different proteins joined together. To be useful, the individual proteins must be separated from the aggregate by protease-catalyzed hydrolysis of peptide bonds. Protease inhibitors prevent this hydrolysis and, in combination with reverse transcriptase inhibitors, slow the reproduction of HIV. Dramatic reductions in the viral load in HIV-infected patients have been achieved with this approach. 

To prevent insolubility resulting from uncontrolled aggregation of extended strands, two adjacent parallel or antiparallel yS-peptide strands can be connected with an appropriate turn segment to form a hairpin. The / -hairpin motif is a functionally important secondary structural element in proteins which has also been used extensively to form stable and soluble a-peptide y9-sheet arrangements in model systems (for reviews, see [1, 4, 5] and references therein). The need for stable turns that can bring the peptide strands into a defined orientation is thus a prerequisite for hairpin formation. For example, type F or II" turns formed by D-Pro-Gly and Asn-Gly dipeptide sequences have been found to promote tight a-pep-tide hairpin folding in aqueous solution. Similarly, various connectors have been... 

Tomski SJ, Murphy RM. Kinetics of aggregation of synthetic beta-amyloid peptide. Arch Biochem Biophys 1992 294 630-638. 

Wood SJ, Maleeff B, Hart T, Wetzel R (1996) Physical, morphological and functional differences between pH 5.8 and 7.4 aggregates of the Alzheimer s amyloid peptide A. J Mol Biol 256(5) 870-877... 

Udupa, P.E., and Sharma, K.K. (2005) Effect of oxidized betaB3-crystallin peptide (152-166) on thermal aggregation of bovine lens gamma-crystallins identification of peptide interacting sites. Exp. Eye. Res. 80(2), 185-196. 

Perutz, M. F., Pope, B. J., Owen, D., Wanker, E. E., and Scherzinger, E. (2002b). Aggregation of proteins with expanded glutamine and alanine repeats of the glutamine-rich and asparagine-rich domains of Sup35 and of the amyloid /1-peptide of amyloid plaques. Proc. Natl. Acad. Sci. USA 99, 5596-5600. 

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