AMT helps in ocular surface reconstruction, promotes rapid epithelial healing and partially restores limbal stem cell function. It can be considered as an effective modality for the ocular surface restoration in chemical and thermal injuries in selected cases. Success rates in acute and chronic cases are comparable.

Flt-1 intraceptors, which are endoplasmic reticulum retention signal-coupled VEGF receptors, significantly suppress hypoxia-induced VEGF secretion by corneal epithelial cells in vitro. In vivo, delivery of naked plasmids expressing these intraceptors inhibits injury-induced upregulation of VEGF, leukocyte infiltration, and corneal neovascularization.

Phosphodiester bond hydrolysis in nucleic acids is a ubiquitous reaction that can be facilitated by enzymes called nucleases, which often use metal ions to achieve catalytic function. While a two-metal-mediated pathway has been well established for many enzymes, there is growing support that some enzymes require only one metal for the catalytic step. Using human apurinic/ apyrimidinic endonuclease (APE1) as a prototypical example and cluster models, this study clarifies the impact of DFT functional, cluster model size, and implicit solvation on single-metal-mediated phosphodiester bond cleavage and provides insight into how to efficiently model this chemistry. Initially, a model containing 69 atoms built from a high-resolution X-ray crystal structure is used to explore the reaction pathway mapped by a range of DFT functionals and basis sets, which provides support for the use of standard functionals (M06-2X and B3LYP-D3) to study this reaction. Subsequently, systematically increasing the model size to 185 atoms by including additional amino acids and altering residue truncation points highlights that small models containing only a few amino acids or β carbon truncation points introduce model strains and lead to incorrect metal coordination. Indeed, a model that contains all key residues (general base and acid, residues that stabilize the substrate, and amino acids that maintain the metal coordination) is required for an accurate structural depiction of the one-metal-mediated phosphodiester bond hydrolysis by APE1, which results in 185 atoms. The additional inclusion of the broader enzyme environment through continuum solvation models has negligible effects. The insights gained in the present work can be used to direct future computational studies of other one-metal-dependent nucleases to provide a greater understanding of how nature achieves this difficult chemistry.

Nucleases catalyze the cleavage of phosphodiester bonds in nucleic acids using a range of metal cofactors. Although it is well accepted that many nucleases rely on two metal ions, the...

The information contained within DNA as a sequence of nucleobases is required for life of most organisms, yet can get altered when the nucleobases are damaged upon exposure to many internal (hormones) and external (ultraviolet sunlight, pollutants) sources. As a result, repair pathways exist to combat the potentially detrimental effects of DNA damage. Nonbulky nucleobase damage (nucleobase oxidation, alkylation and deamination) is commonly removed by the base excision repair (BER) pathway, which involves several enzymes. The first BER enzymes are the DNA glycosylases, which are responsible for identifying the damaged base, flipping the base into the enzyme active site and removing the damaged nucleobase from the sugar–phosphate backbone. Due to the stability of many forms of damaged DNA, the DNA glycosylases must achieve great catalytic power. Understanding the mechanistic details associated with DNA glycosylases is essential for developing detection and treatment strategies for many diseases as abnormal glycosylase function has been associated with cancers, metabolic dysfunctions, neurodegeneration and epigenetic programming during embryo development. Molecular level insight into the function of a wide range of DNA glycosylases has been obtained from computational chemistry, including quantum mechanical cluster calculations, combined quantum mechanics‐molecular mechanics approaches and molecular dynamics simulations. By discussing some of the modeling that has been performed to date on monofunctional DNA glycosylases, the key contributions of the field of computational chemistry to broadening our understanding of the function of this important enzyme family, as well as the critical interplay between traditional biochemical experiments and computer calculations, is highlighted. This article is categorized under: Structure and Mechanism > Reaction Mechanisms and Catalysis Structure and Mechanism > Computational Biochemistry and Biophysics Electronic Structure Theory > Combined QM/MM Methods