<title>Probing protein: DNA interactions using a uniform monolayer of DNA and surface plasmon resonance</title>

Abstract

A method is described for immobilizing double-stranded DNAs to a planar gold surface with high density (1-3x10'2 DNA/cm2, depending on their length) and uniform spacing (-4 nm closest possible DNA-DNA separation). This is accomplished by adsorbing biotinylated DNAs onto a nearly close-packed monolayer of the protein streptavidin. This streptavidin monolayer, which offers -5x1O'2 biotin sites per cm2, is prepared first by adsorbing it onto a mixed sell-assembled monolayer on gold which contains biotin-terminated and oligo(ethylene glycol)-terminated alkylthiolates in a 3/7 ratio. This DNA-functionalized surface resists non-specific protein adsorption and is useful for probing the kinetics and equilibrium binding of proteins to DNA with surface plasmon resonance. This is demonstrated with the Mnt protein, which is found to bind in 3.8:1 ratio to its immobilized DNA operator sequence. This is consistent with its behavior in homogeneous solution. where it binds as a tetramer to its DNA. A sequence with a single base-pair mutation shows nearly as much Mnt binding, but a completely random DNA sequence shows only 5% of this binding. This proves that DNA-binding proteins bind sequence-specifically to double-stranded DNAs which are immobilized to gold with this streptavidin linker layer.

ToF-SIMS and XPS Studies of the Adsorption Characteristics of a Zn-Porphyrin on TiO2

“…Titanium dioxide − modified by self-assembled monolayers is technologically of great interest due to the possibility to adjust surface properties such as wetting behavior, , protein adsorption, , cell interaction in biomedical applications, , and controlled drug release. − …”

“…[10][11][12][13][14][15][16] The orientation of the SAMs on the surface can in many cases determine the surface properties. [17][18][19] Titanium dioxide [20][21][22] modified by self-assembled monolayers is technologically of great interest due to the possibility to adjust surface properties such as wetting behavior, 23,24 protein adsorption, 25,26 cell interaction in biomedical applications, 27,28 and controlled drug release. [29][30][31] SAMs consisting of porphyrin molecules provide ideal archetypes of 2D structures for fundamental studies on one hand, and they can be useful in a host of technology applications on the other hand.…”

Advances in the development of a novel method to be used in proteomics using gold nanobeads

“…DNA replication 1,2 , DNA repair, transcription and many other cellular processes are the result of a complex network between various biological components. Motor proteins, for instance, bind to other molecules and regulate their function.…”

“…The study 1,2,3 of the interaction of proteins with DNA (double or single stranded) covers a broad range of research and includes, the screening of DNA-binding proteins, the identification of a DNA recognition sequence, the analysis of binding affinities between protein and DNA, and the investigation of DNA binding events controlling specific tasks like gene expression. There are a number 1,2 of different methods for the analysis of DNA-protein interactions such as DNA footprinting, electrophoretic mobility shift assays (EMSA), and DNA-protein photocrosslinking, These are standard methods for DNA-protein interaction research.…”

A new optical method for characterizing single molecule interactions based on dark field microscopy

“…The study of DNA-protein interactions includes the screening for DNA-binding protein, the analysis of reaction kinetics, and the determination of the influence of changing environmental conditions on the DNA binding event [2][3][4] .…”