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Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Coordinated Effects Of Distal Mutations On Environmentally Coupled Tunneling In Dihydrofolate Reductase, Lin Wang, Nina M. Goodey, Stephen J. Benkovic, Amnon Kohen Jan 2006

Coordinated Effects Of Distal Mutations On Environmentally Coupled Tunneling In Dihydrofolate Reductase, Lin Wang, Nina M. Goodey, Stephen J. Benkovic, Amnon Kohen

Department of Chemistry and Biochemistry Faculty Scholarship and Creative Works

One of the most intriguing questions in modern enzymology is whether enzyme dynamics evolved to enhance the catalyzed chemical transformation. In this study, dihydrofolate reductase, a small monomeric protein that catalyzes a single C-H-C transfer, is used as a model system to address this question. Experimental and computational studies have proposed a dynamic network that includes two residues remote from the active site (G121 and M42). The current study compares the nature of the H-transfer step of the WT enzyme, two single mutants, and their double mutant. The contribution of quantum mechanical tunneling and enzyme dynamics to the H-transfer step ...


A Modular Data Analysis Pipeline For The Discovery Of Novel Rna Motifs , Justin Schonfeld Jan 2006

A Modular Data Analysis Pipeline For The Discovery Of Novel Rna Motifs , Justin Schonfeld

Retrospective Theses and Dissertations

This dissertation presents a modular software pipeline that searches collections of RNA sequences for novel RNA motifs. In this case the motifs incorporate elements of primary and secondary structure. The motif search pipeline breaks up sets of RNA sequences into shortened segments of RNA primary sequence. The shortened segments are then folded to obtain low energy secondary structures. The distance estimation module of the pipeline then calculates distances between the folded bricks, and then analyzes the resulting distance matrices for patterns;An initial implementation of the pipeline is applied to synthetic and biological data sets. This implementation introduces a new ...


A Penalty Function Method For Constrained Molecular Dynamics , Ajith Gunaratne Jan 2006

A Penalty Function Method For Constrained Molecular Dynamics , Ajith Gunaratne

Retrospective Theses and Dissertations

We propose a penalty-function method for constrained molecular dynamic simulation by defining a quadratic penalty function for the constraints. The simulation with such a method can be done by using a conventional, unconstrained solver only with the penalty parameter increased in an appropriate manner as the simulation proceeds. More specifically, we scale the constraints with their force constants when forming the penalty terms. The resulting force function can then be viewed as a smooth continuation of the original force field as the penalty parameter increases. The penalty function method is easy to implement and costs less than a Lagrange multiplier ...


Distance-Based Nmr Structure Determination And Refinement, Feng Cui Jan 2005

Distance-Based Nmr Structure Determination And Refinement, Feng Cui

Retrospective Theses and Dissertations

Protein structures play a pivotal role in understanding protein functions. X-ray crystallography and nuclear magnetic resonance spectroscopy (NMR) are two main experimental approaches for protein structure determination. The structures determined by NMR are not as accurate as those by X-ray crystallography in general, due to limited distance data (e.g. NOEs) that can be generated from NMR experiments. The NMR modeling algorithms are not well developed either, to produce high-quality structures with desired accuracy and efficiency. To address the NMR modeling issues, a so-called geometric build-up approach for NMR modeling has been developed, which remarkably reduces computing time in determining ...


Two Dimensional Models Of Tumor Angiogenesis , Serdal Pamuk Jan 2000

Two Dimensional Models Of Tumor Angiogenesis , Serdal Pamuk

Retrospective Theses and Dissertations

Angiogenesis, the formation of new capillaries from pre-existing vessels, is essential for tumor progression. It is critical for the growth of primary cancers. In this thesis we present a new approach to angiogenesis, based on the theory of reinforced random walks, coupled with a Michaelis-Menten type mechanism. This views the endothelial cell receptors as the catalyst for transforming angiogenic factor into proteolytic enzyme in order to model the first stage. In our model we use a curvature-induced proliferation term for the endothelial cell equation. Our numerical results indicate that the proliferation of endothelial cells is high at the tip. Also ...


Genetic Variation And Evolution Of Equine Infectious Anemia Virus Rev Quasispecies During Long Term Persistent Infection , Prasith Baccam Jan 2000

Genetic Variation And Evolution Of Equine Infectious Anemia Virus Rev Quasispecies During Long Term Persistent Infection , Prasith Baccam

Retrospective Theses and Dissertations

Genetic variation has been observed in many viruses. Viruses that carry their genetic information in the form of RNA exhibit high mutation rates because the viral polymerase lacks proof-reading mechanisms commonly found in DNA polymerase complexes. The combination of high mutation rates, small genome size, and high replication rates results in a population of closely related viral genotypes, which are commonly referred to as a quasispecies. A consequence of the genetic variation in viruses is possible variation in viral phenotype of the quasispecies population. Furthermore, changes in viral phenotype may be a biologically important factor in progression of disease. Here ...


Study Of Secondary Structure Of Protein Sequences By Linear Algebra , Wei-Hua Hsieh Jan 1991

Study Of Secondary Structure Of Protein Sequences By Linear Algebra , Wei-Hua Hsieh

Retrospective Theses and Dissertations

Using encoding schemes, we study the relation between amino acids and protein structure in linear spaces;Local protein-structure prediction schemes use the amino acid sequences in a short subchain of a protein to predict the protein secondary structure of the middle residue of the chain;Two relatively reliable, objective and quantitative local prediction schemes are Robson et al.'s information theory method and and Qian & Sejnowski's neural network models. The latter achieved 64% accuracy for three-state predictions in 1989, the best prediction performance yet recorded;We assign to the 20 amino acids, through a one-to-one correspondence, the 20 columns (unit vectors) of the 20 x 20 identity matrix. Then any chain of k amino acids may be represented as a ...