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The idea that tunneling is enhanced by the compression of the donor-acceptor distance has attracted significant interest. In particular, recent studies argued that this proposal is consistent with pressure effects on enzymatic reactions, and that the observed pressure effects support the idea of vibrationally enhanced catalysis. However, a careful analysis of the current works reveals serious inco

Recent years have seen dramatic improvements in computer power, allowing ever more challenging problems to be approached. In light of this, it is imperative to have a quantitative model for examining chemical reactivity, both in the condensed phase and in solution, as well as to accurately quantify physical organic chemistry (particularly as experimental approaches can often be inconclusive). Simi

ATP hydrolysis is the driving force of many life processes, yet the exact nature of and contributions to the energetics of this reaction are far from being clear. In particular, it is unclear how much of the driving force of this reaction is due to the separation of the already dissociated ADP + P(i) moieties rather than to the chemical event. This fundamental issue is explored here by ab initio c

Recent years have witnessed an explosion in computational power, leading to attempts to model ever more complex systems. Nevertheless, there remain cases for which the use of brute-force computer simulations is clearly not the solution. In such cases, great benefit can be obtained from the use of physically sound simplifications. The introduction of such coarse graining can be traced back to the e

In recent years, the EVB has become a widely used tool in the QM/MM modeling of reactions in condensed phases and in biological systems, with ever increasing popularity. However, despite the fact that its power and validity have been repeatedly established since 1980, a recent work (Valero, R.; et al. J. Chem. Theory Comput. 2009, 5, 1) has strongly criticized this approach, while not discussing t

Oxyanion holes play a major role in catalyzing enzymatic reactions, yet the corresponding energetics is frequently misunderstood. The main problem may be associated with the nontrivial nature of the electrostatic preorganization effect, without following the relevant formulation. That is, although the energetics of oxyanion holes have been fully quantified in early studies (which include both the

Enzymes play a key role in almost all biological processes, accelerating a variety of metabolic reactions as well as controlling energy transduction, the transcription, and translation of genetic information, and signaling. They possess the remarkable capacity to accelerate reactions by many orders of magnitude compared to their uncatalyzed counterparts, making feasible crucial processes that woul

Phosphate hydrolysis is ubiquitous in biology. However, despite intensive research on this class of reactions, the precise nature of the reaction mechanism remains controversial. Herein, we have examined the hydrolysis of three homologous phosphate diesters. The solvation free energy was simulated by means of either an implicit solvation model (COSMO), hybrid quantum mechanical/molecular mechanica

The idea that enzymes catalyze reactions by dynamical coupling between the conformational motions and the chemical coordinates has recently attracted major experimental and theoretical interest. However, experimental studies have not directly established that the conformational motions transfer energy to the chemical coordinate, and simulating enzyme catalysis on the relevant timescales has been i

DNA polymerases make up a family of enzymes responsible for regulating DNA replication and repair, which in turn maintains the integrity of the genome. However, despite intensive kinetic, crystallographic, and computational studies, elucidation of the detailed enzymatic mechanism still presents a significant challenge. We recently developed an alternative strategy for exploring the fidelity and me

Phosphate monoester and anhydride hydrolysis is ubiquitous in biology, being involved in, amongst other things, signal transduction, energy production, and the regulation of protein function. Therefore, this reaction has understandably been the focus of intensive research. Nevertheless, the precise mechanism by which phosphate monoester hydrolysis proceeds remains controversial. Traditionally, it

Many phosphatases make use of metal ions to aid catalysis of phosphate ester hydrolysis. Here, we investigate the impact of metal ions on the potential energy surface (PES), and hence the preferred reaction mechanism, for a simple model for hydrolysis of phosphate ester monoanions. We show that, while both associative (A(N) + D(N)) and dissociative (D(N) + A(N)) mechanisms are represented on the p

The hydrolysis of phosphate esters is crucially important to biological systems, being involved in, among other things, signaling, energy transduction, biosynthesis, and the regulation of protein function. Despite this, there are many questions that remain unanswered in this important field, particularly with regard to the preferred mechanism of hydrolysis of phosphate esters, which can proceed th

Hybrid quantum mechanical/molecular mechanical (QM/MM) approaches have been used to provide a general scheme for chemical reactions in proteins. However, such approaches still present a major challenge to computational chemists, not only because of the need for very large computer time in order to evaluate the QM energy but also because of the need for proper computational sampling. This review fo

Phosphate ester hydrolysis is ubiquitous in biology, playing a central role in energy production, signaling, biosynthesis, and the regulation of protein function among other things. Although the mechanism of action of the enzymes regulating this reaction has been the focus of intensive research in the past few decades, the correct description of this apparently simple reaction remains controversia

Protein tyrosine phosphatase 1B (PTP1B) is an important drug target for the treatment of type II diabetes and obesity. There are strong indications that a novel class of allosteric inhibitors act by preventing the closure of the WPD-loop [C. Wiesmann, K.J. Barr, J. Kung, J. Zhu, D.A. Erlanson, W. Shen, B.J. Fahr, M. Zhong, L. Taylor, M. Randall, R.S. McDowell, S.K. Hansen, Allosteric inhibition of

Targeted molecular dynamics was used to examine the mechanism of WPD loop closure in PTP1B, which is essential for the activity of the enzyme. Two important regions are identified: the R-loop (residues 113-118), which assists in substrate binding, and the S-loop (residues 198-209), which undergoes a conformational change that appears to be vital for the movement of the WPD loop. The S-loop is adja

Non-islet cell tumor hypoglycemia (NICTH) is one of the paraneoplastic syndromes manifesting severe hypoglycemia caused by aberrant production of high-molecular-weight insulin-like growth factor 2 (big-IGF2). Two surgical cases of extremely large thoracic solitary fibrous tumors (SFT) with unusual history of NICTH are presented. One case manifested severe hypoglycemia after four years of the first

BACKGROUND: Tumor-produced high molecular weight insulin-like growth factor-II (big insulin-like growth factor-II) is considered to cause non-islet cell tumor hypoglycemia. This paper presents a case of surgically resected retroperitoneal liposarcoma that produced big insulin-like growth factor-II.CASE PRESENTATION: Here, we report the case of a 62-year-old woman who presented with an abdominal ma