Aggregation peptide sequences

What was not known by us at that time was that some peptide sequences have a tendency to change conformation when the a-amine hydrochloride or trifluoroacetate is neutralized. In these cases, neutralization in the presence of the incoming activated amino acid reduces the time during which the free a-amine is present, and appears to minimize the conformational change to a (3-sheet structure that can cause aggregation and lead to in-... 

NHA NHS NHSCnSH NIL NIR NLO NLS carbon nanohorn aggregate V- h ycl to x v su cc i n i m i de / yl 11 -mercaptoundecanoyl-A-hydroxysuccinimide ester nanoimprint lithography near infrared nonlinear optics nuclear localization sequence (peptide sequence for nuclear targeting)... 

Many natural channels, particularly those for simple ions, form at the confluence of complex proteins. This mechanism has been simplified by the Gokel group which has prepared alkyl-terminated hexapeptides that contain a short proline containing peptide sequence, GGGPGGG, similar to that found in natural Cl -selective channels [14], These compounds give Cl- selectivity when anchored in phospholipid vesicles. It is assumed that channels form by supramolecular aggregation of the hexapeptides around the proline motif, shown in Fig. 5.6. Such a simple transport mechanism has yet to be seen in Nature but it would not be too surprising if one were to be found. 

We recently demonstrated a method that reproducibly exploits hot spots in metal nanoparticle aggregates for the trace detection of disease-specific enzymes by design [187]. The scheme, shown in Fig. 10.16a, involves the functionalization of gold nanoparticle with thiolated short peptide sequences terminated by an N-(fluorenyl-9-methoxycarbonyl) (FMOC) group. Nanoparticle aggregation is then driven by n-n interactions between the terminating FMOC groups [157]. Hot spots... 

The absolute control over the genes that encode for the proteins readily allows the introduction of different functionalities that can be attached to synthetic polymers. Kopecek et al. [88,89] used this methodology to produce coiled-coil peptide sequences, e.g. (VSSLESK)n containing a histidine tag on the end. The hydrophobic interaction between the side groups of the valines and leucines in the sequence causes the protein to as-siune a helical or coil type structure. These hydrophobic interactions then cause several coils to further aggregate to form so called coiled coils. This coiled coil aggregation can be disrupted by temperature, pH and solvent. A copolymer of poly[N-(2-hydroxy-propyl) methacrylamide- co-(N, N"-dicarboxymethylaminopropyl)methacrylamide], (p[HPMA-co-DAMA]) with... 

This review covers the literature on the aggregation of (homo)polypeptide hybrid copolymers and copolypeptides in dilute solution, which was published up to June 2005 a recent review on amphiphiles consisting of peptide sequences is given elsewhere in [12]. It was a particular concern to give a comprehensive overview on secondary structure effects in the self-assembly of these copolymers. Briefly presented are also structures in concentrated solutions (lyotropic phases) and in heterophase systems (see also [14]). 

The peptide sequences employed for this study are shown in Table 1. Each peptide is based on a general AAAX repeating sequence, where the high helical propensity of alanine facilitates the formation of an or-helix 24, 25). Lysine residues were introduced to impart water solubility and prevent peptide aggregation. Tyrosine was placed at the C-terminus of the peptide to allow concentration determination. The placement of Phe and Phe analogues at /, /+4... 

Because longer peptides enable more coverage of a protein and better ability to study its interactions, the ability to synthesize longer chains is highly desirable. Conventional Fmoc SPPS has enabled routine assembly of peptide sequences of up to 30 to 40 amino acids when aggregation is not an important issue. 

---