Aggregation of trypsin and trypsin inhibitor by Al cation

Small angle X-ray scattering investigation of ionic liquid effect on the aggregation behavior of globular proteins

Globular proteins are well-folded model proteins, where ions can substantially influence their structure and aggregation. Ionic liquids (ILs) are salts in the liquid state with versatile ion combinations. Understanding the IL effect on protein behavior remains a major challenge. Here, we employed small angle X-ray scattering to investigate the effect of aqueous ILs on the structure and aggregation of globular proteins, namely, hen egg white lysozyme (Lys), human lysozyme (HLys), myoglobin (Mb), β-lactoglobulin (βLg), trypsin (Tryp) and superfolder green fluorescent protein (sfGFP). The ILs contain ammonium-based cations paired with the mesylate, acetate or nitrate anion. Results showed that only Lys was monomeric, whereas the other proteins formed small or large aggregates in buffer. Solutions with over 17 mol% IL resulted in significant changes in the protein structure and aggregation. The Lys structure was expanded at 1 mol% but compact at 17 mol% with structural changes in loop regions. HLys formed small aggregates, with the IL effect similar to Lys. Mb and βLg mostly had distinct monomer and dimer distributions depending on IL type and IL concentration. Complex aggregation was noted for Tryp and sfGFP. While the anion had the largest ion effect, changing the cation also induced the structural expansion and protein aggregation.

Examining the Availability and Accessibility of Rehabilitation Services in a Rural District of South Africa: A Mixed-Methods Study

Introduction: Rehabilitation services aim to optimise individuals’ functioning and reduce disability. However, people with disabilities, who represent a key population of users of rehabilitation services, continue to have unmet needs for rehabilitation services that include the provision of assistive devices. This paper examines the availability and accessibility of rehabilitation services in a rural district of South Africa in order to explore why unmet needs for rehabilitation services persist. Methods: All nine district hospitals in a rural district of South Africa were included in the study. Rehabilitation services capacity was assessed by examining the available assistive devices, consumables and human resources at the level of the health facility. Data collection was conducted using the Global Co-operative Assistive Technology [GATE] Assistive Products List, AT2030’s ATScale priority list and the South African National Catalogue of Commodities for Primary Health Care Facilities. Descriptive statistics were then used for the analysis. For the qualitative component, semi-structured interviews were conducted with adults with physical disabilities at household level to explore barriers to accessing assistive device inclusive rehabilitation services and the consequences thereof in the same rural district. An interview guide based on the WHO health system building blocks was used. Thematic content analysis guided the analysis of the interview transcripts. Findings: The findings of the research demonstrate that rehabilitation service capacity in the district was constrained as a result of low availability of assistive devices [2–22%] and consumables [2–47%], as well as, possibly, a shortage of rehabilitation providers [n = 30] with an unequal distribution across health facilities [n = 9]. In addition, people with physical disabilities reported poor referral pathways, financial constraints, transport and road consideration and equipment unavailability as barriers to accessing rehabilitation services. Moreover, these barriers to access predisposed individuals to finance-, health- and person-related harm. Conclusion: Rehabilitation service availability is constrained by a lack of service capacity in rural South Africa. In addition, the rehabilitation services in district hospitals are not adequately accessible because of existing barriers to enable key populations to achieve optimised functioning.

The interaction of graphene oxide-silver nanoparticles with trypsin: Insights from adsorption behaviors, conformational structure and enzymatic activity investigations

In this work, we synthesized graphene oxide-silver nanoparticles (GO-AgNPs) hybrids by one-pot method. Since there are relatively few reports on whether GO-AgNPs bind and change the structure and function of trypsin, A variety of methods were employed to systematically characterize the molecular interaction between GO-AgNPs and trypsin. Results exhibited that GO-AgNPs bound with trypsin to form a ground state complex. GO-AgNPs had higher adsorption capacity for trypsin compared with single GO. Langmuir-Blodgett assembly method was used to confirm that AgNPs did not interfere with the adsorption of trypsin by GO. The secondary structure and the microenvironment of amino acid residues of trypsin were altered after interacting with GO-AgNPs. In addition, GO-AgNPs can enhance the activity of trypsin and promote the hydrolysis of bovine serum protein (BSA) by trypsin. These findings provide important support for the application of GO-based nanocomposites in the efficient immobilization of enzymes.