다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

A versatile means of intracellular labeling: injection of biocytin and its detection with avidin conjugates

Metal ions are essential to many chemical, biological, and environmental processes. In the past two decades, many DNA-based metal sensors have emerged. While the main biological role of DNA is to store genetic information, its chemical structure is ideal for metal binding via both the phosphate backbone and nucleobases. DNA is highly stable, cost-effective, easy to modify, and amenable to combinatorial selection. Two main classes of functional DNA were developed for metal sensing: aptamers and DNAzymes. While a few metal binding aptamers are known, it is generally quite difficult to isolate such aptamers. On the other hand, DNAzymes are powerful tools for metal sensing since they are selected based on catalytic activity, thus bypassing the need for metal immobilization. In the last five years, a new surge of development has been made on isolating new metal-sensing DNA sequences. To date, many important metals can be selectively detected by DNA often down to the low parts-per-billion level. Herein, each me...

Metal Sensing by DNA

From the metal ions and metal compounds that are known to bind to DNA, many anticancer Pt(II) and Ru(II)/Ru(III) compounds are known to have ligand-exchange kinetics in the same order of magnitude as the division of tumor cells. The present article discusses this process in detail with special attention to cisplatin and related compounds and the cellular binding sites and processes of such compounds. Detailed platinated DNA structures are presented and discussed in light of the mechanistic studies of metal antitumor compounds. It is now known that platinum antitumor drugs eventually end up on the DNA. However, it remains a challenge to understand how (fast) they reach the DNA and how they are removed. The kinetics of ligand exchange around platinum appear to play a crucial role, and the possible role of other ligands as intermediates, especially those with S-donor sites, is of great interest. New types of Pt compounds with additional functionalities influencing DNA binding and kinetics are discussed in the context of steric and H-bonding properties. A comparison is made with more sterically crowded Ru complexes. The effects on activity and correlations with structural and kinetic properties are clues in understanding the biological activities of these classes of compounds.

https://www.pnas.org/content/pnas/100/7/3611.full.pdf

New clues for platinum antitumor chemistry: Kinetically controlled metal binding to DNA

Fenton-like copper redox chemistry revisited: Hydrogen peroxide and superoxide mediation of copper-catalyzed oxidant production

Adenosine 5′-triphosphate (ATP4−) and related nucleoside 5′-triphosphates (NTP4−) serve as substrates in the form of metal ion complexes in enzymic reactions taking part thus in central metabolic processes. With this in mind, the coordination chemistry of NTPs is critically reviewed and the conditions are defined for studies aiming to describe the properties of monomeric complexes because at higher concentrations (>1 mM) self-stacking may take place. The metal ion (M2+) complexes of purine–NTPs are more stable than those of pyrimidine–NTPs; this stability enhancement is attributed, in accord with NMR studies, to macrochelate formation of the phosphate-coordinated M2+ with N7 of the purine residue and the formation degrees of the resulting isomeric complexes are listed. Furthermore, the formation of mixed-ligand complexes (including also those with buffer molecules), the effect of a reduced solvent polarity on complex stability and structure (giving rise to selectivity), the use of nucleotide analogues as antiviral agents, and the effect of metal ions on group transfer reactions are summarized.

Nucleoside 5′-triphosphates: self-association, acid–base, and metal ion-binding properties in solution

Ternary complexes in solution. VIII. Complex formation between the copper(II)-2,2'-bipyridyl 1:1 complex and ligands containing oxygen and/or nitrogen donor atoms

Guanine is an important nucleobase residue in nucleic acids; for example, the anticancer drug cisplatin, cis-[(NH3)2PtCl2], preferably binds to N7 of this site. In this study the effect of (N7)-coordinated Ni2+ (which is expected to correspond to that of Zn2+), Cu2+, and cis-a2Pt2+ or trans-a2Pt2+ (where a = NH3 or CH3NH2) on the acid–base properties of guanine derivatives (see diagram) is quantified. Several related purines are included for comparison. Micro-acidity-constant evaluations are presented and more than 60 acidity constants are listed.

Effects of (N7)-Coordinated Nickel(II), Copper(II), or Platinum(II) on the Acid–Base Properties of Guanine Derivatives and Other Related Purines[≠]

Ternary complexes in solution. XI. Complex formation between the cobalt(II)-, nickel(II)-, copper(II)-, and zinc(II)-2,2'-bipyridyl 1:1 complexes and ethylenediamine, glycinate, or pyrocatecholate

The acidity constants of protonated 7,9-dimethylguanine, 7-methylguanosine, 7,9-dimethylhypoxanthine, 7-methylinosine, 9-methyladenine, 1,9-dimethyladenine, 7,9-dimethyladenine and 1-methyladenosine were determined in aqueous solution at 25 °C and I
= 0.1 M (NaNO3). In those instances where pKa > 2 potentiometric pH titrations were used for the determinations; when pKa < 2, UV spectrophotometric and 1H-NMR shift measurements were employed (25 °C). In these latter instances, where I is often larger than 0.1 M, the H0 scale was applied to define the H+ activity of the strong acid (HClO4; HNO3). A combination of the present results with values taken from our earlier work allowed us to quantify the intrinsic acidic properties in aqueous solution of the (N1)H0 or
+ and (N7)H+ sites via
micro acidity constant schemes for seven purine derivatives and to calculate the tautomeric ratios regarding the monoprotonated species, that is N7–N1·H versus H·N7–N1 meaning that in one isomer H+ is at the N1 site and in the other at N7. A plot of the micro acidity constants pkN7–N1H·N7–N1, which quantify the acidity of the (N7)H+ site, versus the macro acidity constants pKa/(N1)H, which largely refer to the release of the proton from the (N1)H unit, results in a straight line for the guanine and hypoxanthine derivatives. This fact allows estimation of the micro acidity constant for any related derivative provided a value for pKa/(N1)H is known. The presented results are also meaningful for nucleic acids because they quantify the acid–base properties of their individual sites.

Rolf Griesser

Papers

Nucleoside 5′-triphosphates: self-association, acid–base, and metal ion-binding properties in solution

Ternary complexes in solution. VIII. Complex formation between the copper(II)-2,2'-bipyridyl 1:1 complex and ligands containing oxygen and/or nitrogen donor atoms

Effects of (N7)-Coordinated Nickel(II), Copper(II), or Platinum(II) on the Acid–Base Properties of Guanine Derivatives and Other Related Purines[≠]

Ternary complexes in solution. XI. Complex formation between the cobalt(II)-, nickel(II)-, copper(II)-, and zinc(II)-2,2'-bipyridyl 1:1 complexes and ethylenediamine, glycinate, or pyrocatecholate

Comparison of the acid–base properties of purine derivatives in aqueous solution. Determination of intrinsic proton affinities of various basic sites