Turkey egg white lysozyme. Free energy, enthalpy, and steady state kinetics of reaction with N-acetylglucosamine oligosaccharides

An inquiry-based biochemistry laboratory structure emphasizing competency in the scientific process: a guided approach with an electronic notebook format

The laboratory setting is an exciting and gratifying place to teach because you can actively engage the students in the learning process through hands-on activities; it is a dynamic environment amenable to collaborative work, critical thinking, problem-solving and discovery. The guided inquiry-based approach described here guides the students through their laboratory work at a steady pace that encourages them to focus on quality observations, careful data collection and thought processes surrounding the chemistry involved. It motivates students to work in a collaborative manner with frequent opportunities for feedback, reflection, and modification of their ideas. Each laboratory activity has four stages to keep the students' efforts on track: pre-lab work, an in-lab discussion, in-lab work, and a post-lab assignment. Students are guided at each stage by an instructor created template that directs their learning while giving them the opportunity and flexibility to explore new information, ideas, and questions. These templates are easily transferred into an electronic journal (termed the E-notebook) and form the basic structural framework of the final lab reports the students submit electronically, via a learning management system. The guided-inquiry based approach presented here uses a single laboratory activity for undergraduate Introductory Biochemistry as an example. After implementation of this guided learning approach student surveys reported a higher level of course satisfaction and there was a statistically significant improvement in the quality of the student work. Therefore we firmly believe the described format to be highly effective in promoting student learning and engagement.

Oxindolealanine-62 lysozyme: equilibrium, calorimetric, and kinetic studies of the reaction with N-acetylglucosamine oligosaccharides

Oxindolealanine-62 lysozyme, formed by reaction with N-bromosuccinimide and purified by using affinity chromatography, was examined in its binding of homologous oligosaccharides of N-acetylglucosamine and in its catalysis of hydrolysis and of transglycosylation of the hexasaccharide of N-acetylglucosamine. Equilibrium binding constants were determined by changes in absorbance or fluorescence associated with ligand binding. Enthalpies of binding were measured calorimetrically. The pattern of variation of delta Go and delta Ho of binding with ligand chain length and pH was different for oxindolealanine-62 lysozyme compared with native lysozyme. These results indicate that the interactions of the ABC region of the active site with substrates are substantially altered by Trp-62 oxidation, more than expected for loss only of the Trp-62 interactions. The partitioning of the glycosyl enzyme intermediate between reaction with a saccharide acceptor (transglycosylation) and reaction with water is unaffected by oxidation of Trp-62. Similarly, the pattern of cleavage of the hexasaccharide, predominantly to tetra- and disaccharide, is unaffected by oxidation of Trp-62. The 2000-fold slower rate of catalytic reaction (relative to free enzyme and substrate) apparently reflects a sterically hindered fit of the substrate into the active site of the modified enzyme and not a special catalytic importance of Trp-62. The geometry of the transition state for oligosaccharide hydrolysis is inferred to be the same for native and oxidized enzymes.

Isolation of lysozyme on chitosan

Lysozyme has been immobilized on chitosan, a polyaminosaccharide, without using any intermediate reagent. The best pH conditions for operating the chitosan columns have been determined and the best eluting agent was found to be a 2% solution of propylamine. The lysozyme activity was determined after reacting lysozyme with the product of glycolchitin and Remazol Brilliant Blue R. The recovery of lysozyme from chicken egg white yields lysozyme with 55% activity.

Tryptophan fluorescence and homology in lysozymes and alpha-lactalbumins

Steady-state and transient fluorescence properties of turkey lysozyme, human lysozyme, and bovine alpha-lactalbumin are compared to those of hen lysozyme and hen lysozyme derivatives. Tryptophan fluorescence appears to be sufficiently sensitive to environment so that a small divergence in sequence can alter the fluorescence properties of one or more of the sequentially equivalent tryptophans in these proteins. Thus, an understanding of the fluorescence of one protein cannot necessarily be extended to a homologous protein in a simple manner, and the use of fluorescence to document structural similarity in homologous proteins is likely to be difficult. In addition, the results with alpha-lactalbumin and human lysozyme suggest that multiple conformations of these proteins exist in solution, and that interconversion of these conformations is slow compared to the fluorescence lifetime.