Biochemistry, Biophysics, and Structural Biology Commons^™

Mechanisms Of Connexin-46 And -50 Intercellular Channel Function And Stability By Molecular Dynamics Simulations, Bassam George Haddad

Dissertations and Theses

Gap junctions make up a class of intercellular channels that characteristically connect the cytoplasm of directly apposed cells through large assemblies, or plaques, constituted by a multitude of intercellular channels. Gap junction mediated intercellular communication is critical for a variety of physiological functions, from coordinating electrical impulses in the heart and brain to maintaining homeostasis in most tissues. There are 21 isoforms of connexins, the constituent subunit of the gap junction, expressed in a tissue dependent manner. Gap junctions formed from different isoforms exhibit distinct biophysical properties, such as gating kinetics and sensitivity, as well as unique permeability and selectivity …

Modulation Of Protein Dynamics By Ligand Binding And Solvent Composition, Richard J. Lindsay

Doctoral Dissertations

Many proteins undergo conformational switching in order to perform their cellular functions. A multitude of factors may shift the energy landscape and alter protein dynamics with varying effects on the conformations they explore. We apply atomistic molecular dynamics simulations to a variety of biomolecular systems in order to investigate how factors such as pressure, the chemical environment, and ligand binding at distant binding pockets affect the structure and dynamics of these protein systems. Further, we examine how such changes should be characterized. We first investigate how pressure and solvent modulate ligand access to the active site of a bacterial lipase …

Bridging The 12-6-4 Model And The Fluctuating Charge Model, Pengfei Li

Chemistry: Faculty Publications and Other Works

Metal ions play important roles in various biological systems. Molecular dynamics (MD) using classical force field has become a popular research tool to study biological systems at the atomic level. However, meaningful MD simulations require reliable models and parameters. Previously we showed that the 12-6 Lennard-Jones nonbonded model for ions could not reproduce the experimental hydration free energy (HFE) and ion-oxygen distance (IOD) values simultaneously when ion has a charge of +2 or higher. We discussed that this deficiency arises from the overlook of the ion-induced dipole interaction in the 12-6 model, and this term is proportional to 1/r …

Simulated Breathing: Application Of Molecular Dynamics Simulations To Pulmonary Lung Surfactant, Maksymilian Dziura, Basel Mansour, Mitchell Dipasquale, P. Charukeshi Chandrasekera, James W. Gauld, Drew Marquardt

Chemistry and Biochemistry Publications

In this review, we delve into the topic of the pulmonary surfactant (PS) system, which is present in the respiratory system. The total composition of the PS has been presented and explored, from the types of cells involved in its synthesis and secretion, down to the specific building blocks used, such as the various lipid and protein components. The lipid and protein composition varies across species and between individuals, but ultimately produces a PS monolayer with the same role. As such, the composition has been investigated for the ways in which it imposes function and confers peculiar biophysical characteristics to …

Computational Analysis Of Type 3 Iodothyronine Deiodinase: Potential Inhibitors, Substrate Binding, And Dimer Structure, Eric Scott Marsan

Chemistry & Biochemistry Theses & Dissertations

Thyroid hormones (THs) in mammalian tissues are crucial for development and maintaining metabolic homeostasis. Iodothyronine deiodinases (Dios) remove iodines from THs by a selenocysteine (Sec) residue, which either activates or inactivates them. Halogen bonding (XB) has been proposed to describe the interaction between the Se and I atoms of the T4-Dio complex. Disruption of TH homeostasis by xenobiotics, such as polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) can cause deleterious effects on the endocrine system. Experimental studies have indicated that PBDEs and PCBs could disrupt TH homeostasis by inhibiting Dio through XB formation. However, no current quantitative study exists …

Functional Role Of The N-Terminal Domain In Connexin 46/50 By In Silico Mutagenesis And Molecular Dynamics Simulation, Umair Khan

University Honors Theses

Connexins form intercellular channels known as gap junctions that facilitate diverse physiological roles, from long-range electrical and chemical coupling to nutrient exchange. Recent structural studies on Cx46 and Cx50 have defined a novel and stable open state and implicated the amino-terminal (NT) domain as a major contributor to functional differences between connexin isoforms. This thesis presents two studies which use molecular dynamics simulations with these new structures to provide mechanistic insight into the function and behavior of the NTH in Cx46 and Cx50. In the first, residues in the NTH that differ between Cx46 and Cx50 are swapped between the …

Molecular Dynamic Simulation Of The Complex Folding Patterns Of Apolipoprotein A1 In Various Concentrations Of Potassium Chloride, Hannah Holmberg

Honors Theses

Apopliprotein or ApoA-1 is a complex lipoprotein that functions in the removal of cholesterol from the blood, removing cholesterol from the area around white blood cells and promoting the excretion of lipids through the lymphatic system. Previous research has found that ApoA-1 shows both folded and unfolded conformations depending on the concentration of NaCl in solution in the water around it. The protein was studied using molecular dynamics simulations. Once this state of equilibrium was reached, various structural properties of the protein were measured including the radius of gyration and the radial distribution function. The goal of the project was …

The Effect Of The Apolipoprotein A1 (Apoa1): The Stability And Folding In Potassium Chloride Environment, Alexandra Paladian

Honors Theses

Healthy levels of potassium chloride (KCl) can significantly affect the workings of the cholesterol level of the human body and how they pertain to an individual person. The search for a better salt additive for the human diet can provide a better option for people who experience high cholesterol levels and heart disease. The study focuses on the experimental design of the Molecular Dynamic (MD) simulation of the Apolipoprotein A1 (APOA1) in the potassium ion solution environment to determine the stability and folding of the protein. The study also compares its data to the previous experimental design of chloride ions …

Computational And Experimental Investigation Into The Determinants Of Protein Structure, Folding, And Stability In The Β-Grasp Superfamily, John T. Bedford Ii

Chemistry & Biochemistry Theses & Dissertations

Elucidating the mechanisms of protein folding and unfolding is one of the greatest scientific challenges in basic science. The overarching goal is to predict three-dimensional structures from their amino acid sequences. Understanding the determinants of protein folding and stability can be facilitated through the study of evolutionarily related but diverse proteins. Insights can also be gained through the study of proteins from extremophiles that may more closely resemble the primordial proteins. In this doctoral research, three aims were accomplished to characterize the structure, folding and unfolding behavior within the β-grasp superfamily. We propose that the determinants of structure, stability, and …

Understanding And Exploiting Protein Allostery And Dynamics Using Molecular Simulations, Sukrit Singh

Arts & Sciences Electronic Theses and Dissertations

Protein conformational landscapes contain much of the functionally relevant information that is useful for understanding biological processes at the chemical scale. Understanding and mapping out these conformational landscapescan provide valuable insight into protein behaviors and biological phenomena, and has relevance to the process of therapeutic design.

While structural biology methods have been transformative in studying protein dynamics, they are limited by technicallimitations and have inherent resolution limits. Molecular dynamics (MD) simulations are a powerful tool for exploring conformational landscapes, and provide atomic-scale information that is useful in understanding protein behaviors. With recent advances in generating datasets of large timescale simulations …

Structure Based Prediction Of A Novel Gpr120 Antagonist Based On Pharmacophore Screening And Molecular Dynamics Simulations, Ajay Pal Mr, James Curtin, Gemma K. Kinsella

Articles

The G-protein coupled receptor, GPR120, has ubiquitous expression and multifaceted roles in modulating metabolic and anti-inflammatory processes. Recent implications of its role in cancer progression have presented GPR120 as an attractive oncogenic drug target. GPR120 gene knockdown in breast cancer studies revealed a role of GPR120-induced chemoresistance in epirubicin and cisplatin-induced DNA damage in tumour cells. Higher expression and activation levels of GPR120 is also reported to promote tumour angiogenesis and cell migration in colorectal cancer. Some agonists targeting GPR120 have been reported, such as TUG891 and Compound39, but to date development of small-molecule inhibitors of GPR120 is limited. …

Understanding The Relationship Between Local Environmental Changes And The Function Of The Ph Low Insertion Peptide, Violetta Burns Casamayor

Graduate Theses, Dissertations, and Problem Reports

Cancer is the second leading cause of death in the US with over 1.7 million new cases each year. Current cancer treatments tend to also target healthy tissues due to similarities with cancerous ones, resulting in acute side effects. Early detection is the best approach towards defeating cancer, however, modern imaging techniques require sizeable samples, often implying a late stage in the disease. One common attribute of tumors is their acidic microenvironment, which can be taken advantage of.

The pH Low Insertion Peptide (pHLIP) is a membrane-active peptide that can take advantage of the acidic microenvironment surrounding cancer cells. pHLIP …