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by Eric Martz
Black spots are mutations of concern in SARS-CoV-2 spike protein reported by UK scientists in December, 2020. RNA viruses mutate quickly so mutations are expected. These mutations may speed up contagion, but are unlikely to cause more severe COVID-19 and unlikely to reduce vaccine effectiveness. ACE2 binding residues. Animation shows priming via cleavage by furin.
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by Eric Martz
A historical review on sculptures and physical models of macromolecules.

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F Wang, Y Gu, JP O'Brien, SM Yi, SE Yalcin, V Srikanth, C Shen, D Vu, NL Ing, AI Hochbaum, EH Egelman, NS Malvankar. Cell 2019 doi: 10.1016/j.cell.2019.03.029
Bacteria living in anaerobic environments (no oxygen) need alternative electron acceptors in order to get energy from their food. An acceptor abundant in the earth's crust is red iron oxide ("rust"), which gets reduced to black iron oxide (magnetite). Many bacteria, such as Geobacter, get their metabolic energy by transferring electrons to acceptors that are multiple cell diameters distant, using protein nanowires. These were long thought to be pili. But when the structure of the nanowires was solved in 2019, to everyone's surprise, they turned out to be unprecedented linear polymers of multi-heme cytochromes. The hemes form an electrically conductive chain in the cores of these nanowires.

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by Eric Martz
The Ramachandran Principle says that alpha helices, beta strands, and turns are the most likely conformations for a polypeptide chain to adopt, because most other conformations are impossible due to steric collisions between atoms. Check Show Clashes to see where non-bonded atoms are overlapping, and thus in physically impossible positions.

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