The authors are with the Sch. Med., Indiana Univ., Indianapolis, Indiana. A student lab experiment was described for the measurement of triglycerides in biological samples. The procedure demonstrates extraction and later transesteriflcation of the triglycerides to yield glycerol, periodate oxidation; the formation of 1,4-dihydro-3, 5-diacetyl lutidine, and quanti-tation by absorbence measurement at 410 mm. -- AATA
The surfaces of mammalian cells are coated with complex carbohydrates, many terminated with a negatively charged N-acetylneuraminic acid residue. This motif is specifically targeted by pathogens, including influenza viruses and many pathogenic bacteria, to gain entry into the cell. A necessary step in the influenza virus life cycle is the release of viral particles from the cell surface; this is achieved by cleaving N-acetylneuraminic acid from cell surface glycans with a virally-produced neuraminidase. Here we present a laboratory exercise to model this process using a glycoprotein as a glycan carrier and using real time nuclear magnetic resonance (NMR) spectroscopy to monitor N-acetylneuraminic acid release as catalyzed by neuraminidase. A time-resolved two dimensional data processing technique, statistical total correlation spectroscopy (STOCSY), enhances the resolution of the complicated 1D glycoprotein spectrum and isolates characteristic peaks corresponding to substrates and products. This exercise is relatively straightforward and leads students through a wide range of biologically and chemically relevant procedures, including use of NMR spectroscopy, enzymology and data processing techniques.
There are several ways to approach the subject of environmental education for the professional chemist. In this paper the author briefly discusses the general approaches that seem to be necessary in bridging the gap between a strict academic approach to chemistry and the practical aspects of problem solving in pollution abatement and control. Also, in view of diminishing graduate training grants, the approach of the Environmental Protection Agency to preparation of pollution abatement and control personnel at the graduate level is discussed.
An experimental system for detecting infrared absorption using the photoacoustic (PA) effect is described. It is aimed for use at high-school level to illustrate the difference in infrared (IR) absorption among the gases contained in the atmosphere in connection with the greenhouse effect. The experimental system can be built with readily available components and is suitable for small-group experiments. The PA signal from a greenhouse gas (GHG), such as CO(2), H(2)O, and CH(4), can be detected down to a concentration of 0.1%. Since the basic theory of the PA effect in gases due to IR absorption is straightforward, the experiments with this PA system are accessible to students. It can be shown that there is a significant difference in IR absorption between GHGs and the major components of the atmosphere, N(2), O(2), and Ar, which helps students understand that the minor components, that is, the GHGs, determine the IR absorptivity of the atmosphere.
The nutritional importance of trace amounts of certain metals in foodstuffs is is well established. This undergraduate analytical service course allows students to go through the entire process of sampling, sample preparation, final measurement, and data reduction with a programmable calculator.
The accident experience during 1960-1969 in the clinical laboratories of a university hospital and a private hospital were compared. The frequency rates per million man hours for disabling injuries was 2.21 and the severity rate was 14.1 in the university hospital laboratory. These two rates were zero in the private hospital. Minor accidents which did not cause loss of time were also reviewed. In both laboratories the personnel most frequently involved in minor accidents were medical technologists. The areas of the body most frequently affected were fingers, hands and arms. Improper handling of glass was the major cause of these minor accidents.
The following set of exercises provides a simple visual method of demonstrations some of the characteristics of enzymes in general, such as heat and pH lability and inhibition, as well as some specific properties of bromelain intide hydrolysis. These experiments can be used with freshman in introductory courses and juniors in biochemistry.
A chemical research program at a public high school has been developed. The full-year Advanced Chemical Research class (ACR) in the high school enrolls 20 to 30 seniors each year, engaging them in long-term experimental projects. Through partnerships involving university scientists, ACR high school students have had the opportunity to explore a number of highly sophisticated original research projects. As an example of the quality of experimental work made possible through these high school-university partnerships, this article describes the development of a novel method for the oxidation of ethidium bromide, a mutagen commonly used in molecular biology. Data collected from ACR alumni show that the ACR program is instrumental in encouraging students to pursue careers in scientific fields and in creating life-long problem-solvers.
Many high school laboratory experiments demonstrate concepts related to biological evolution, but few exist that allow students to investigate life's chemical origins. This series of laboratory experiments has been developed to allow students to explore and appreciate the deep connection that exists between prebiotic chemistry, chemical evolution, and contemporary biological systems. In the first experiment of the series, students synthesize adenine, one of the purine nucleobases of DNA and RNA, from plausibly prebiotic precursor molecules. Students compare their product to authentic standards using thin-layer chromatography. The second and third experiments of the series allow students to extract DNA from a familiar organism, the strawberry, and hydrolyze it, releasing adenine, which they can then compare to the previously chemically-synthesized adenine. A fourth, optional experiment is included where the technique of thin-layer chromatography is introduced and chromatographic skills are developed for use in the other three experiments that comprise this series. Concepts relating to organic and analytical chemistry, as well as biochemistry and DNA structure, are incorporated throughout, allowing this series of laboratory experiments to be easily inserted into existing laboratory courses and to reinforce concepts already included in any high school chemistry or biology curriculum.
Protein folding is an exploding area of research in biophysics and physical chemistry. Here, we describe the integration of several techniques, including absorption spectroscopy, fluorescence spectroscopy, and Förster resonance energy transfer (FRET) measurements, to probe important topics in protein folding. Cytochrome c is used as a model protein; comparison of conformational stabilities ( ΔGH2O∘) measured via two chemical denaturants, urea and guanidinium hydrochloride, illustrate important concepts in protein folding and intermolecular interactions. In addition, the determination of intraprotein distances based upon the FRET pair Trp-59 and the heme group for unfolded states of cytochrome c highlights the evolution of the protein structure under unfolding conditions. Analysis and discussion of these results provide opportunities to gain in-depth understanding of models for protein folding while enhancing students' skills with optical techniques. Collectively, the combination of optical spectroscopy, rigorous quantitative analysis, and a focus on biophysics illustrates the significance of fundamental research at the growing intersection of chemistry, biology, and physics.
High-Performance Liquid Chromatography (HPLC) simulation software has long been recognized as an effective educational tool, yet we found that existing HPLC simulators are either too expensive, out-dated, or lack many important features we deemed necessary to make them widely useful for educational purposes. Here we describe a free, open-source HPLC simulator we developed that we believe meets this need. The web-based simulator is uniquely sophisticated, yet accessible to a diverse user group with varied expertise in HPLC. It features intuitive controls and indicators for a wide range of experimental conditions, and it displays a graphical chromatogram to provide immediate feedback when conditions are changed. The simulator can be found at hplcsimulator.org. At that website, we also provide a number of example problem sets that can be used by educators to more easily incorporate the simulator into their curriculum. Comments from students who used the simulator in an undergraduate Analytical Chemistry class were very positive.