Specifications Grading has Improved my Courses!

Specifications grading is a way of restoring rigor, motivating students, and saving faculty time as stated in the title of Linda Nilson\u27s book promoting this method. While there are many variations across disciplines, I will present how I am using specifications grading in my Organic Chemistry courses. I label course objectives as essential or non-essential, and students must master these with a quiz score of 80% or greater to obtain the points. Students are allowed multiple attempts to master course objectives

Effect of an arginine-to-isoleucine active site mutation on Escherichia coli malate dehydrogenase enzymatic activity

Citric acid cycle enzymes function in an environment with numerous substrate analogues and therefore contain active site residue organizations that confer high substrate specificity. Extensive research into the catalytic mechanism of Escherichia coli malate dehydrogenase (eMDH) has identified arginine81 as being crucial to catalysis. In this investigation, an engineered eMDH having an Ile81 rather than an Arg81 (R81I) was isolated using a hexahistadine (His6) tag. Enzymatic activity of the R81I mutant with respect to malate, lactate, and pyruvate was explored. The R81I mutant did show significant activity toward malate, but did not show significant activity toward lactate or pyruvate. Investigations into an R81F mutant eMDH and an R81W/M85E dimutant eMDH may provide more insight into the eMDH catalytic mechanism

Site-Directed Mutagenesis of Malate Dehydrogenase: A Class Project

Malate dehydrogenase (MDH) is an important enzyme in an organism’s metabolic pathways. MDH is found in almost all living cells and catalyzes the conversion of malate to oxaloacetate which also involves nicotinamide dehydrogenase (NAD) as a coenzyme. A method to study how an enzyme operates is to alter one of its amino acids and compare the activity of the enzyme before and after the mutation. As a class project in Advanced Biochemistry during the spring semester of 2018, we are working as a team to propose and carry out a point-based mutation on MDH

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Dielectric Response and Conductivity of Poly(Propylene Oxide) Sodium Poly-Iodide Complexes. Discussion of Charge Transport by an Ion Relay Mechanism

The addition of iodine to poly(propylene oxide), PPO, with or without Nal results in the formation of polyiodides as evidenced by a resonance Raman band at 170 cm 1. The conductivities of these complexes, measured with ac and dc methods, show both ohmic and nonohmic responses characteristic of electronic and ionic conductors, respectively. The conductivity rises with both increasing iodine and salt concentrations. Low-temperature conductivity data showed a very small inflection in the vicinity of Tg for the host polymer, indicating that dynamics of the host polymer are only weakly coupled to the mechanism for conductivity in the polyiodide system. An ion relay along polyiodide chains is consistent with these observations. For comparison purposes, Raman spectra and conductivities were studied for structurally characterized metal compounds containing infinite I3 species. In these structures the conductivity is very low, and this is attributed to structural pinning of the polyiodides, which would block ion relay or carrier hopping charge transport

Soluble epoxide hydrolase is a susceptibility factor for heart failure in a rat model of human disease

We aimed to identify genetic variants associated with heart failure by using a rat model of the human disease. We performed invasive cardiac hemodynamic measurements in F(2) crosses between spontaneously hypertensive heart failure (SHHF) rats and reference strains. We combined linkage analyses with genome-wide expression profiling and identified Ephx2 as a heart failure susceptibility gene in SHHF rats. Specifically, we found that cis variation at Ephx2 segregated with heart failure and with increased transcript expression, protein expression and enzyme activity, leading to a more rapid hydrolysis of cardioprotective epoxyeicosatrienoic acids. To confirm our results, we tested the role of Ephx2 in heart failure using knockout mice. Ephx2 gene ablation protected from pressure overload-induced heart failure and cardiac arrhythmias. We further demonstrated differential regulation of EPHX2 in human heart failure, suggesting a cross-species role for Ephx2 in this complex disease