DNA-based

Other biomoleciiles imaged have included all DNA bases [44], polysaccharides [45] and proteins [46, 4lZ]. In many cases there is strong evidence that the imaging process is facilitated by the presence of iiltrathin (conducting) water films on the surface of the sample [48, 49 and 50],... 

Ionov R, De Coninok J and Angelova A 1996 On the origin of the long-range attraotion between surfaoe-eonfined DNA bases Thin Solid Films 284-285 347-51... 

Voss R F 1992 Evolution of long-range fraotal oorrelations and 1/f noise in DNA base sequenoes Phys. Rev. Lett. 68 3805-8... 

Mirkin C A ef a/1996 A DNA-based method for rationally assembling nanopartioles into maorosoopio materials Nature 382 607... 

Loweth C J ef a/1999 DNA-based assembly of gold nanoorystals Angew. Chem. Int Ed. 38 1808... 

The DNA base pairs guanine (G), cytosine (C), adenine (A) and thymine (T). The uracil-2,6-diaminopyridine pair can also form three hydrogen bonds but has a much lower association constant than G-C. 

CR Polymerase Chain Reaction. Widely used method for amplifying a DNA base sequence... 

By similar logic, protein affinity Hbraries have been constmcted to identify protein—protein combining sites, as in antibody—antigen interaction (19) and recombinant Hbraries have been made which produce a repertoire of antibodies in E. coli (20). In another case, a potential DNA-based therapeutic strategy has been studied (21). DNAs from a partially randomized Hbrary were selected to bind thrombin in vitro. Oligonucleotides, termed aptamers that bound thrombin shared a conserved sequence 14—17 nucleotides long. 

The primary stmcture of DNA is based on repeating nucleotide units, where each nucleotide is made up of the sugar, ie, 2 -deoxyribose, a phosphate, and a heterocycHc base, N. The most common DNA bases are the purines, adenine (A) and guanine (G), and the pyrimidines, thymine (T) and cytosine (C) (Fig. 1). The base, N, is bound at the I -position of the ribose unit through a heterocycHc nitrogen. 

Results on DNA-based biosensors will be presented they have been used mainly for two kind of applications 1) for the determination of low-molecular weight compounds witlr affinity for nucleic acids and 2) for the detection of hybridization reaction. 

Figure 9.11 Amino acid sequences of homeodomains from four differenf franscription factors Anfp is from fhe Antennapedia gene in the fruitfly Drosophila, a2 is from the yeast Mat o2 gene, eng is from fhe engrailed gene in Drosophila and POU is from fhe POU homeodomain in the mammalian gene Oct-1. Residues colored green form the hydrophobic core of the homeodomain, blue form nonspecific interactions with the DNA backbone and red form contacts with the edges of the DNA bases.

Figure 9.12 Schematic diagram of the structure of the heterodimeric yeast transcription factor Mat a2-Mat al bound to DNA. Both Mat o2 and Mat al are homeodomains containing the helix-turn-helix motif. The first helix in this motif is colored blue and the second, the recognition helix, is red. (a) The assumed structure of the Mat al homeodomain in the absence of DNA, based on Its sequence similarity to other homeodomains of known structure, (b) The structure of the Mat o2 homeodomain. The C-terminal tail (dotted) is flexible in the monomer and has no defined structure, (c) The structure of the Mat a 1-Mat a2-DNA complex. The C-terminal domain of Mat a2 (yellow) folds into an a helix (4) in the complex and interacts with the first two helices of Mat a2, to form a heterodimer that binds to DNA. (Adapted from B.J. Andrews and M.S. Donoviel, Science 270 251-253, 1995.)...

When the RNA of a retrovirus is transcribed, what DNA base is the complement of the uracil in the viral RNA J... 

Pairing properties of 2-hydroxyadenine and 8-oxoadenine with four standard DNA bases were studied at the Hartree-Fock level [99JST59] and adenine-hydrogen peroxide complexes at the MP2 and DFT levels [99JPC(A)4755]. 

From what DNA base sequence was the following RNA sequence transcribed ... 

Crosslinks result from the reaction of a bifunctional electrophilic species with DNA bases and imply a covalent link between two adjacent DNA strands which inhibits DNA replication. Primary targets within bases are N7 and 06 in guanine and N3 in cytosine. The initial lesions are removed by the suicide enzyme alkyltrans-ferase, whereas nucleotide excision repair is needed for frilly established crosslinks. 

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