Peptide surface

Fig. 3. (A) Disposition of afi unit in the membrane, based on sequence information [14,15], selective proteolytic digestion of the a subunit [5,6] and hydrophobic labelling (Table 1). The model for the (S subunit is based on sequencing of surface peptides and identification of S-S bridges [64,65]. T, T2 and C3 show location of proteolytic splits. CHO are glycosylated asparagines in the P subunit. (B) Peptide fragments remaining in the membrane after extensive tryptic digestion of membrane-bound Na,K-ATPase from outer medulla of pig kidney as described by Karlish et al. [7,58].

Fig. 3. Analysis of peptide-lipid interactions using ProteinChip arrays. Vesicles are absorbed to H50 ProteinChip arrays via interactions with C8 functional groups, creating a supported lipid monolayer on the chip surface (A, B). Samples are applied to the chip, incubated for 5 min (C), and washed to remove nonspecifically bound proteins (D). Matrix is added (E), and the array is introduced into the ProteinChip reader, where the laser is fired onto the chip surface. Peptides retained on the surface are finally resolved by TOF-MS, displaying mass-to-charge versus signal intensity (F, G). (Adapted from ProteinChip technology training course, Bio-Rad Laboratories.)...

Houseman et al. prepared a peptide chip by Diels-Alder-mediated reaction of kinase-peptide substrates with a self-assembled monolayer of alkanethiolates on gold surface. Peptide phosphorylation was determined by incubating the peptide microarrays with c-src protein-tyrosine kinase followed by quantitation with a phos-phoryl imager. In the presence of soluble inhibitors at a range of concentrations, dose-dependent inhibition of phosphorylation against a number of peptide substrates could be determined on a single chip. ... 

Tuchsen, E., and Woodward, C., Mechanism of surface peptide proton exchange in bovine pancreatic trypsin inhibitor. Salt effects and O-protonation, J. Mol. Biol. 185,421-430 (1985). 

Figure 32.2 Cell surface peptide hydrolysis (A) and amino acid oxidation (B) using the fluorescent compound Lucifer "Vellow Anhydride (LYA)-tetraalanine and lysine, respectively. Fluorescent products are measured along with the added tracer hy high performance liquid chromatography (HPLC) and products can be further degraded or taken up by cells.

Morra M (2006) Biochemical modification of titanium surfaces peptides and ECM proteins. Eur Cell Mater 12 1-15... 

The hydrated electrons react with the carbonyl groups of the peptide chain or with disulfides and the protonated imidazole ring of histidine. It is assumed that the main sites of electron attachment are the surface peptide groups, and this is followed by internal electron migration into a potential sink, either to histidine or to a disulfide bridge (Mae 1987). As a final result of irradiation action on peptides in aqueous systems (and also in solid state) fragmentation of the peptide chain and cross-Unking takes place. 

Figure 5.29 Vancomycin dimers targeting cell surface peptides. X—X = S—S, CH=CH.

Some (broad) range of surface peptide concentration should be targeted, below which the cells may not recognize the peptide and above which the surface may be excessively adhesive. 

Another approach comes from Professor Christopher T. Walsh s laboratory at Harvard Medical School. The Walsh laboratory studies the biosynthesis of natural products (natural products are small molecules created by nature). What does natural product biosynthesis have to do with cellular imaging Like the AGT method where a DNA repair protein is used, it turns out that some of the proteins involved in natural product assembly are useful for labeling the cell surface. Peptide carrier proteins (PCPs) are 80- to 120-amino acid domains of nonribosom peptide synthetases (NRPSs). NRPSs are protein megacomplexes used by many microbial species, like Pseudomonas and Streptomyces, to biosynthesize natural products from common amino acid precursors. An enzyme called a phosphop-antetheinyl transferase will covalently attach the 4 -phosphopantethei-nyl moiety of coenzyme A to a specific serine residue in the PCP domain. One phosphopantetheinyl transferase, Sfp from a microbe... 

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