Engineering enhanced thermostability into the Geobacillus pallidus nitrile hydratase.

Nitrile hydratases (NHases) are important biocatalysts for the enzymatic conversion of nitriles to industrially-important amides such as acrylamide and nicotinamide. Although thermostability in this enzyme class is generally low, there is not sufficient understanding of its basis for rational enzyme design. The gene expressing the Co-type NHase from the moderate thermophile, Geobacillus pallidus RAPc8 (NRRL B-59396), was subjected to random mutagenesis. Four mutants were selected that were 3 to 15-fold more thermostable than the wild-type NHase, resulting in a 3.4-7.6 â€‹kJ/mol increase in the activation energy of thermal inactivation at 63 â€‹°C. High resolution X-ray crystal structures (1.15-1.80 â€‹Å) were obtained of the wild-type and four mutant enzymes. Mutant 9E, with a resolution of 1.15 â€‹Å, is the highest resolution crystal structure obtained for a nitrile hydratase to date. Structural comparisons between the wild-type and mutant enzymes illustrated the importance of salt bridges and hydrogen bonds in enhancing NHase thermostability. These additional interactions variously improved thermostability by increased intra- and inter-subunit interactions, preventing cooperative unfolding of α-helices and stabilising loop regions. Some hydrogen bonds were mediated via a water molecule, specifically highlighting the significance of structured water molecules in protein thermostability. Although knowledge of the mutant structures makes it possible to rationalize their behaviour, it would have been challenging to predict in advance that these mutants would be stabilising.

Systems Approach to Human Hair Fibers: Interdependence Between Physical, Mechanical, Biochemical and Geometric Properties of Natural Healthy Hair.

Contextual interpretation of hair fiber data is often blind to the effects of the dynamic complexity between different fiber properties. This intrinsic complexity requires systems thinking to decipher hair fiber accurately. Hair research, studied by various disciplines, follows a reductionist research approach, where elements of interest are studied from a local context with a certain amount of detachment from other elements or contexts. Following a systems approach, the authors are currently developing a cross-disciplinary taxonomy to provide a holistic view of fiber constituents and their interactions within large-scale dynamics. Based on the development process, this paper presents a review that explores the associated features, interrelationships and interactive complexities between physical, mechanical, biochemical and geometric features of natural, healthy hair fibers. Through the review, the importance of an appropriate taxonomy for interpreting hair fiber data across different disciplines is revealed. The review also demonstrates how seemingly unrelated fiber constituents are indeed interdependent and that these interdependencies may affect the behavior of the fiber. Finally, the review highlights how a non-integrative approach may have a negative impact on the reliability of hair data interpretation.

Emerging Diagnostic and Therapeutic Potentials of Human Hair Proteomics.

The use of noninvasive human substrates to interrogate pathophysiological conditions has become essential in the post- Human Genome Project era. Due to its high turnover rate, and its long term capability to incorporate exogenous and endogenous substances from the circulation, hair testing is emerging as a key player in monitoring long term drug compliance, chronic alcohol abuse, forensic toxicology, and biomarker discovery, among other things. Novel high-throughput 'omics based approaches like proteomics have been underutilized globally in comprehending human hair morphology and its evolving use as a diagnostic testing substrate in the era of precision medicine. There is paucity of scientific evidence that evaluates the difference in drug incorporation into hair based on lipid content, and very few studies have addressed hair growth rates, hair forms, and the biological consequences of hair grooming or bleaching. It is apparent that protein-based identification using the human hair proteome would play a major role in understanding these parameters akin to DNA single nucleotide polymorphism profiling, up to single amino acid polymorphism resolution. Hence, this work seeks to identify and discuss the progress made thus far in the field of molecular hair testing using proteomic approaches, and identify ways in which proteomics would improve the field of hair research, considering that the human hair is mostly composed of proteins. Gaps in hair proteomics research are identified and the potential of hair proteomics in establishing a historic medical repository of normal and disease-specific proteome is also discussed.

Intravenous glutathione for skin lightening: Inadequate safety data.

BACKGROUND: Glutathione (GSH) is the most abundant naturally occurring non-protein thiol that protects mammalian cells from oxidative stress. Intravenous (IV) GSH for skin lightening is advertised by clinics in South Africa and internationally online, yet to date no published review on the subject exists. Methods. We conducted a MEDLINE search (to 30 September 2015) of GSH use for skin lightening and of all indications in medicine, to evaluate its safety. Results. Two controlled clinical trials (GSH capsules: 60 patients; 2% glutathione disulphide lotion: 30 patients) and a case series (GSH lozenges: 30 patients) reported a significantly decreased melanin index. A case series (GSH soap: 15 patients) reported skin lightening based on photography. Two systematic reviews of IV GSH for preventing chemo-induced toxicity and a third review of adjuvant therapy for Parkinson's disease altogether included 10 trials. Most trials reported either no or minimal GSH adverse effects, but all had treatment durations of a few doses (IV) or 4 -12 weeks. No study reported long-term IV GSH use. Conclusion. In spite of widespread reported use, there are no studies of IV GSH use for skin lightening or of its safety for chronic use (for any indication). The switch from brown to red melanin production may increase the risk of sun-induced skin cancers in previously protected individuals. Regulatory assessment of systemic GSH administration for cosmetic use by the Medicines Control Council seems urgently warranted to protect consumers from potential side-effects and from complications of IV infusions. This is especially concerning because of reports of GSH bought online. Effective topical GSH may be useful for hyperpigmented skin disorders, but this requires scientific scrutiny. The debate on the merits of cosmetic skin lightening is best handled by multidisciplinary teams.