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Polypeptide Sequences (polypeptide + sequence)

Distribution by Scientific Domains

Chemistry	80%

Selected Abstracts

Biomimetic synthesis of gold nanoparticles and their aggregates using a polypeptide sequence

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 8 2007
Zheng Wang
Abstract The polypeptide sequence MS14 (MHGKTQATSGTIQS) was used to explore a new method for biomimetic preparation of gold nanoparticles and their aggregates. Self-congregation of gold nanoparticles into aggregates in MS14 aqueous solution and self-assembly of gold crystallites onto the designed complex of MS14-PET film [protonated poly(ethylene terephthalate)] proved the specific gold-binding characteristic of the single-copy peptide MS14 in vitro. In aqueous solution MS14 could recover Au(III) to Au(0), tested by means of TEM, EDX and XPS. Further research suggested that the pH of the solution and the concentration of Au(III) influenced the morphology and size of the gold nanoparticles formed. In addition, extra reducing agent, sodium citrate, was introduced into the HAuCl4,MS14 system and uniformly dispersed nanoparticles under neutral condition were obtained. Finally, we discuss the possible mechanism of this biomimetic synthesis. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Structural characterization of the N-terminal mineral modification domains from the molluscan crystal-modulating biomineralization proteins, AP7 and AP24

BIOPOLYMERS, Issue 5 2004
Brandon A. Wustman
Abstract The AP7 and AP24 proteins represent a class of mineral-interaction polypeptides that are found in the aragonite-containing nacre layer of mollusk shell (H. rufescens). These proteins have been shown to preferentially interfere with calcium carbonate mineral growth in vitro. It is believed that both proteins play an important role in aragonite polymorph selection in the mollusk shell. Previously, we demonstrated the 1,30 amino acid (AA) N-terminal sequences of AP7 and AP24 represent mineral interaction/modification domains in both proteins, as evidenced by their ability to frustrate calcium carbonate crystal growth at step edge regions. In this present report, using free N-terminal, C, -amide "capped" synthetic polypeptides representing the 1,30 AA regions of AP7 (AP7-1 polypeptide) and AP24 (AP24-1 polypeptide) and NMR spectroscopy, we confirm that both N-terminal sequences possess putative Ca (II) interaction polyanionic sequence regions (2 × ,DD, in AP7-1, ,DDDED, in AP24-1) that are random coil-like in structure. However, with regard to the remaining sequences regions, each polypeptide features unique structural differences. AP7-1 possesses an extended ,-strand or polyproline type II-like structure within the A11,M10, S12,V13, and S28,I27 sequence regions, with the remaining sequence regions adopting a random-coil-like structure, a trait common to other polyelectrolyte mineral-associated polypeptide sequences. Conversely, AP24-1 possesses random coil-like structure within A1,S9 and Q14,N16 sequence regions, and evidence for turn-like, bend, or loop conformation within the G10,N13, Q17,N24, and M29,F30 sequence regions, similar to the structures identified within the putative elastomeric proteins Lustrin A and sea urchin spicule matrix proteins. The similarities and differences in AP7 and AP24 N-terminal domain structure are discussed with regard to joint AP7,AP24 protein modification of calcium carbonate growth. © 2004 Wiley Periodicals, Inc. Biopolymers 2004 [source]

Investigation of de novo Totally Random Biosequences, Part I

CHEMISTRY & BIODIVERSITY, Issue 8 2006
A General Method for in vitro Selection of Folded Domains from a Random Polypeptide Library Displayed on Phage
Abstract This paper reports the initial phase of a research aimed at investigating the folding frequency within a large library of polypeptides generated with a totally random sequence by phage-display technique. Resistance to proteolytic digestion has been used as a first, rudimentary folding criterion. The present paper describes, in particular, the development of a phage-display vector which has a selectable N-terminal affinity tag so that, after controlled proteolysis, the tag is cleaved from the phage. This enables the positive selection of phages that carry proteolytically resistant proteins. To test this system, avian pancreatic polypeptide (APP), one of the smallest proteins with a known structure, was chosen as a model, and its gene was inserted in a plasmid that was then used for phage display. A sequence of three amino acids, corresponding to a substrate for thrombin, was introduced at different locations within the APP sequence without significantly modifying the tertiary structure, as determined by circular dichroism (CD) analysis. These sequences were then used to show that the target tripeptide sequence was protected against proteolysis by the overall folding of the chain. Thus, these results show that the method permits the discrimination between folded and unfolded protein domains displayed on phage. The application of this protocol to a large library of totally random polypeptide chains is discussed as a preliminary to successive work, dealing with the production of totally random polypeptide sequences. [source]

Circular dichroism studies on repeating polypeptide sequences of abductin,

CHIRALITY, Issue 7 2005
Brigida Bochicchio
Abstract The secondary structure of abductin was investigated by CD and NMR studies of several synthetic peptides. Results obtained with these peptides showed the dominant conformations to be the polyproline II (PPII) structure in aqueous solution and different types of ,-turns in the less polar solvent trifluoroethanol. Accordingly, a preliminary structure,elasticity relationship for abductin, not unlike that currently accepted for elastin, is proposed. Chirality 17:364,372, 2005. © 2005 Wiley-Liss, Inc. [source]

Isolation and characterization of a wound inducible phenylalanine ammonia-lyase gene (LsPAL1) from Romaine lettuce leaves

PHYSIOLOGIA PLANTARUM, Issue 3 2004
Reinaldo Campos
Phenylalanine ammonia-lyase (PAL) catalyses the first step controlling the rate of phenylpropanoid metabolism. Wounding is a ubiquitous stress in nature and in the harvesting and preparation of fruits and vegetables that induces an increase in PAL activity, an accumulation of phenolic compounds and subsequent tissue browning. A wound-inducible PAL gene (LsPAL1) was isolated from Romaine lettuce by RT-PCR. The putative protein encoded by LsPAL1 is similar to predictive polypeptides sequences for other PALs. The kinetics of PAL mRNA accumulation is similar to those of induced PAL enzyme activity, with enzyme activity following mRNA accumulation by 12 h. Wound-induced PAL transcripts accumulated in cells close to the wound sites. Tissue printing showed that PAL mRNA was associated with tissue next to the epidermis and vascular bundles. A heterologous PAL protein was expressed in E. coli and was found to show significant PAL activity. [source]