Tailoring trehalose for biomedical and biotechnological applications

Trehalose is a non-reducing sugar whose ability to stabilize biomolecules has brought about its widespread use in biological preservation applications. Trehalose is also an essential metabolite in a number of pathogens, most significantly the global pathogen Mycobacterium tuberculosis, though it is absent in humans and other mammals. Recently, there has been a surge of interest in modifying the structure of trehalose to generate analogs that have applications in biomedical research and biotechnology. Non-degradable trehalose analogs could have a number of advantages as bioprotectants and food additives. Trehalose-based imaging probes and inhibitors are already useful as research tools and may have future value in the diagnosis and treatment of tuberculosis, among other uses. Underlying the advancements made in these areas are novel synthetic methods that facilitate access to and evaluation of trehalose analogs. In this review, we focus on both aspects of the development of this class of molecules. First, we consider the chemical and chemoenzymatic methods that have been used to prepare trehalose analogs and discuss their prospects for synthesis on commercially relevant scales. Second, we describe ongoing efforts to develop and deploy detectable trehalose analogs, trehalose-based inhibitors, and non-digestible trehalose analogs. The current and potential future uses of these compounds are discussed, with an emphasis on their roles in understanding and combatting mycobacterial infection.

A comparison of mass measurements with the stem using the wet-film technique with and without polylysine treatment

The wet film technique of injection of a specimen into a drop on a thin carbon film (for eventual freeze-drying and mass analysis in the STEM) has been described and shown to give a uniform background and, in general, good biological preservation of specimens. However, an occasional specimen either does not absorb well or is of necessity very dilute. Many specimens absorb to polylysine-treated grids nearly 10-fold better than to thin C alone. We describe here our adaptation of the polylysine treatment originally described by Williams, and our finding that polylysine-treated thin C does not give significantly worse errors in mass measurements than thin C alone.To prepare a specimen, thin C is floated off cleaved NaCl onto a dish of water. Grids covered with holey film are dropped onto the thin C. A grid is picked up, inverted and washed with water, buffer, specimen, buffer. For poly lysine grids, after washing with water, 5 μl of 10 μg/ml poly lysine is injected for 1 minute.