Here we investigate a novel signal-on electrochemical DNA sensor based on the use of a clamp-like DNA probe that binds a complementary target sequence through two distinct and sequential events, which lead to the formation of a triplex DNA structure. We demonstrate that this target-binding mechanism can improve both the affinity and specificity of recognition as opposed to classic probes solely...

Many people believe that American biologist James Watson and English physicist Francis Crick discovered DNA in the 1950s. In reality, this is not the case. Rather, DNA was first identified in the late 1860s by Swiss chemist Friedrich Miescher. Then, in the decades following Miescher's discovery, other scientists--notably, Phoebus Levene and Erwin Chargaff--carried out a series of research effor...

Franklin William Stahl studied DNA replication, bacteriophages, and genetic recombination in the US during the mid-twentieth and early twenty-first centuries. With his colleague Matthew Meselson, Stahl performed an experiment called the Meselson-Stahl experiment, which provided evidence for a process called semi-conservative DNA replication. Semi-conservative replication is a process in which e...

We consider stateless counter machines which mix the features of one-head counter machines and a special type of two-head Watson-Crick automata (WK-automata). Our Watson-Crick counter machines are biologically motivated. They have two heads that read the input starting from the two extremes. The reading process is finished when there are no more symbols between the heads, i.e., every letter of ...

The nucleotide sequence dependence of the DNA and RNA secondary structure is a problem of current interest in molecular biophysics. The key role of stacking interactions in determining this dependence is widely accepted [1, 2], It is be­ lieved that the propeller twisting of base pairs, ob­ served in the structure of both nucleic acids and crystals of nucleosides and nucleotides is a direct man...

Cooperativity in oligonucleotide-directed sequence-specific recognition of DNA by triple helix formation can be enhanced by the addition of discrete dimerization domains. The equilibrium association constants for cooperative binding of oligonucleotides that dimerize by Watson-Crick hydrogen bonds and occupy adjacent sites on double helical DNA by triple helix formation have been measured by qua...

The crystal structure of the rare-cutting HNH restriction endonuclease PacI in complex with its eight-base-pair target recognition sequence 5'-TTAATTAA-3' has been determined to 1.9 A resolution. The enzyme forms an extended homodimer, with each subunit containing two zinc-bound motifs surrounding a betabetaalpha-metal catalytic site. The latter is unusual in that a tyrosine residue likely init...

Novel Janus-type nucleoside analogues (1a-d) were synthesized. Their pyrimido[4,5-d]pyrimidine base moiety has one face with a bidentate Watson-Crick donor-acceptor (DA) H-bond array of adenine and the other face with an acceptor-donor (AD) H-bond array of thymine. These nucleosides may self-associate through the self-complementary base pair. Indeed, in the solid state, compound 6d displayed a ...

one of the great intellectual achievements of 20th century biological science: deciphering of the DNA code by Jim Watson and Francis Crick (Watson & Crick, 1953). It is also the month and year in which The National Human Genome Research Institute announced completing the human genome (Collins et al, 2003). Is this the time to hold a memorial mass to bury social psychiatry, an outmoded corpus of...

The X-ray crystallographic structure of the RNA duplex [r(CGCAIGCG)]2 has been refined to 2.5 A. It shows a symmetric internal loop of two non-Watson-Crick base pairs which form in the middle of the duplex. The tandem A-I/I-A pairs are related by a crystallographic two-fold axis. Both A(anti)-I(anti) mismatches are in a head-to-head conformation forming hydrogen bonds using the Watson-Crick pos...