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In this review, we focus on the biophysical and structural aspects of the oligomeric states of physiologically intrinsically disordered proteins and peptides tau, amyloid-β and α-synuclein and partly disordered prion protein and their isolations from animal models and human brains. These protein states may be the most toxic agents in the pathogenesis of Alzheimer's and Parkinson's disease. It was shown that oligomers are important players in the aggregation cascade of these proteins. The structural information about these structural states has been provided by methods such as solution and solid-state NMR, cryo-EM, crosslinking mass spectrometry, AFM, TEM, etc., as well as from hybrid structural biology approaches combining experiments with computational modelling and simulations. The reliable structural models of these protein states may provide valuable information for future drug design and therapies. [ABSTRACT FROM AUTHOR]

Since Coronavirus disease 2019 (COVID-19) still presents a considerable threat, it is beneficial to provide therapeutic supplements against it. In this respect, glycoprotein lactoferrin (LF) and lactoferricin (LFC), a natural bioactive peptide yielded upon digestion from the N-terminus of LF, are of utmost interest, since both have been shown to reduce infections of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the virus responsible for COVID-19, in particular via blockade of the virus priming and binding. Here, we, by means of biochemical and biophysical methods, reveal that LF directly binds to the S-protein of SARS-CoV-2. We determined thermodynamic and kinetic characteristics of the complex formation and mapped the mutual binding sites involved in this interaction, namely the N-terminal region of LF and the receptor-binding domain of the S-protein (RBD). These results may not only explain many of the observed protective effects of LF and LFC in SARS-CoV-2 infection but may also be instrumental in proposing potent and cost-effective supplemental tools in the management of COVID-19. [ABSTRACT FROM AUTHOR]

Lactoferrin is an iron-binding glycoprotein present in most human exocrine fluids, particularly breast milk. Lactoferrin is also released from neutrophil granules, and its concentration increases rapidly at the site of inflammation. Immune cells of both the innate and the adaptive immune system express receptors for lactoferrin to modulate their functions in response to it. On the basis of these interactions, lactoferrin plays many roles in host defense, ranging from augmenting or calming inflammatory pathways to direct killing of pathogens. Complex biological activities of lactoferrin are determined by its ability to sequester iron and by its highly basic N-terminus, via which lactoferrin binds to a plethora of negatively charged surfaces of microorganisms and viruses, as well as to mammalian cells, both normal and cancerous. Proteolytic cleavage of lactoferrin in the digestive tract generates smaller peptides, such as N-terminally derived lactoferricin. Lactoferricin shares some of the properties of lactoferrin, but also exhibits unique characteristics and functions. In this review, we discuss the structure, functions, and potential therapeutic uses of lactoferrin, lactoferricin, and other lactoferrin-derived bioactive peptides in treating various infections and inflammatory conditions. Furthermore, we summarize clinical trials examining the effect of lactoferrin supplementation in disease treatment, with a special focus on its potential use in treating COVID-19. [ABSTRACT FROM AUTHOR]

Nanolitre-sized drops are characteristic of high-throughput protein crystallization screening. Traditionally, reliable nanolitre drop dispensing has required the use of robotics. This work describes the design and development of a protocol for the reproducible manual assembly of nanolitre-sized protein vapour-diffusion crystallization trials in a 96/192-drop format. The protocol exploits the repetitive-pipetting mode of handheld motorized pipettes together with simple tools available in standard laboratories. The method saves precious protein material without sacrificing the effectiveness of the screening process. To verify the approach, two monoclonal antibody Fab fragments were crystallized alone and in a complex with tau peptide antigens in 0.2-0.5 µl drops. Crystals grown directly from the screen conditions in sitting drops on 96-well plates diffracted up to 1.6 Å resolution on a synchrotron source. The results proved that successful crystallization in nanolitre high-throughput format is affordable even in the absence of expensive robotic instrumentation. [ABSTRACT FROM AUTHOR]