Biophysics Commons^™

Effects Of Pore-Forming Peptides (Melittin And Magainin 2) On The Phospholipid Bilayer Interior, Elmukhtar Ehmed Alhatmi

Dissertations and Theses

Antimicrobial peptides (AMPs) are one of the most promising solutions to drug-resistant bacteria. Melittin and magainin 2 are two of the most representative and extensively studied AMPs. In this research, I investigated the interaction of these two AMPs with three models of cell membranes: 80% POPC 20% POPG, 40%POPC 40% POPE and 20% POPG, and 80%POPC 20%POPG plus 30% mole fraction of cholesterol. Time-resolved fluorescence emission and fluorescence anisotropy decays of the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH) were analyzed to determine the effects of AMPs on the bilayer headgroup packing and changes in the interior of the phospholipid bilayer during the …

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 …

No Oxygen, No Water: The Unique Physiology Of Annual Killifish Embryos Across Development, Daniel Erik Zajic

Dissertations and Theses

For most vertebrates, an abundance of oxygen is necessary for the production of ATP and the maintenance of cellular homeostasis. The absence of oxygen, even for brief periods, quickly leads to ATP depletion which can lead to irreparable damages to sensitive organs, such as the brain and heart. However, certain vertebrates demonstrate an extraordinary ability to thrive and recover fully from periods of no oxygen (anoxia). The annual killifish (Austrofundulus limnaeus) lives in ephemeral ponds in the Maracaibo basin of Venezuela and their embryos have the remarkable ability to not only survive anoxic periods for months, but also …

The Effect Of Styrene-Maleic Acid (Sma) Copolymers On Solubilizing Lipid Bilayers And Forming Nanodiscs, Ghada Alramadan

Dissertations and Theses

Cell membranes, or plasma membranes, play an essential role in the structure and the function of living cells. In 1972, the fluid mosaic membrane model was the first unifying paradigm of membrane structure. It is no longer considered adequate because evidence of many non-homogeneous lipid structures in both natural and model membranes have been discovered over the past thirty years. The field of membrane biophysics now uses updated versions of the mosaic model, which consists of the complex mixture of different lipid species. The lipid species found in natural membranes produce a range of dynamic, laterally segregated, non-homogeneous domains, which …

The Effect Of Docosahexaenoic Acid (Dha)-Containing Phosphatidylcholine (Pc) On Liquid-Ordered And Liquid-Disordered Coexistence, Yongwen Gu

Dissertations and Theses

Plasma membranes are essential to both the structure and function of mammalian cells. The first unifying paradigm of membrane structure, the Fluid Mosaic Model, is no longer considered adequate to describe the many non-homogeneous lipid structures that have been observed in both natural and model membranes over the past approximately thirty years. The field of membrane biophysics now appreciates that the complex mixture of different lipid species found in natural membranes produces a range of dynamic, laterally segregated, non-homogeneous structures which exist on time scales ranging from microseconds to minutes.

When sphingomyelin (SM), POPC and cholesterol are all present in …

Calcium Transport Inhibition, Stimulation, And Light Dependent Modulation Of The Skeletal Calcium Release Channel (Ryr1) By The Prototropic Forms Of Pelargonidin, Thomas Joseph Dornan

Dissertations and Theses

The principle calcium regulator in the muscle cell is the calcium ion release channel (RyR). Improper calcium homeostasis in the muscle cell is the foundation of many pathological states and has been targeted as a contributing factor to ventricular tachycardia, which is known to precede sudden cardiac arrest.

Numerous endogenous and exogenous compounds can affect the way RyR regulates calcium. In this study the anthocyanidin Pelargonidin (Pg), an important natural colorant and dietary antioxidant, is evaluated for its effect on regulating the transport of calcium through the RyR1 of skeletal muscle sarcoplasmic reticulum. Pelargonidin undergoes time dependent structural changes in …