pH-dependent interactions of biologically important metal ions with hen egg white lysozyme based on its hydration properties: Thermodynamic and mechanistic insights.

Importance of metal ion selectivity in biomolecules and their key role in proteins are widely explored. However, understanding the thermodynamics of how hydrated metal ions alter the protein hydration and their conformation is also important. In this study, the interaction of some biologically important Ca2+, Mn2+, Co2+, Cu2+, and Zn2+ ions with hen egg white lysozyme at pH 2.1, 3.0, 4.5 and 7.4 has been investigated. Intrinsic fluorescence studies have been employed for metal ion-induced protein conformational changes analysis. Thermostability based on protein hydration has been investigated using differential scanning calorimetry (DSC). Thermodynamic parameters emphasizing on metal ion-protein binding mechanistic insights have been well discussed using isothermal titration calorimetry (ITC). Overall, these experiments have reported that their interactions are pH-dependent and entropically driven. This research also reports the strongly hydrated metal ions as water structure breaker unlike osmolytes based on DSC studies. These experimental results have highlighted higher concentrations of different metal ions effect on the protein hydration and thermostability which might be helpful in understanding their interactions in aqueous solutions.

Color vision in civil aviation.

Color vision deficiency (CVD) is a condition that results in individuals being unable to distinguish differences between certain colors. Occupational color vision standards were introduced in aviation in 1919 by The Aeronautical Commission of the International Civil Air Navigation Authority. Concern has been expressed during the last few years that the current color vision standards in aviation may be too stringent and, at the same time, also variable across the world. The tests employed do not always reflect the tasks pilots encounter in today's aviation environment. This ambiguity leads to the possible exclusion of deserving applicants for selection as aircrew. The compatibility of CVD with aircraft crew is assessed by medical personnel using clinical diagnosis tests on the ground level. These clinical tests were developed specifically to detect the presence, nature, and severity of CVD. No clinical tests yet provide a measure of operational performance in operating an aircraft. Arbitrary pass marks have been assigned to clinical tests such that a failing candidate will either be subject to operational restrictions or excluded completely. The prescribed clinical tests and associated pass marks vary considerably between regulators. While an individual may be subject to no restrictions in one jurisdiction, they may be excluded in another. This article highlights newer diagnostic techniques adopted by different countries for assessing color vision to see for the scope of evidence-based guidelines for minimum color vision requirements for flight crew as well as for civil aviation in India.