- Pka Of The Side Chain R Groups D 3 9 E 4 2 H 6 0 C 8 3 Y 10 1 K 10 5 And R 12 5 Pka Of Amino Ac 1 (29.47 KiB) Viewed 69 times
2. In the SARS-CoV-2 virus, the spike protein mediates attachment and fusion of the virus to the host cell membrane via ACE2, enabling entry inside. During its lifecycle, after the synthesis of new viral proteins, proteolytic cleavage occurs via a furin site separating the nascent spike protein into two subunits: S1 and S2. The furin site absent in other group-2B coronaviruses is characterized by four amino acids (RRAR) forming an RXXR cleavage motif for serine proteases via a 4mer insertion (PRRA). It is a small solvent-exposed coil on the spike. Scientists would like to study some of the biochemical behaviors of this site and have synthesized the region containing the cleavage motif as an oligopeptide: SPRRARS. • (a) Draw the structure of SPRRARS that would predominate at physiological pH 7.4 (partial charge is denoted with a delta, 8). • (b) Calculate the overall net charge of SPRRARS oligopeptide at pH 7.4 to the nearest 0.01. • (c) In running through an ion-exchange column of sulfate S-resin, what pH fraction would this X be exected in a gradient of acid-to-base elution?