BIOL 3155 Lecture Notes - Lecture 3: Envelope, Tobacco Mosaic Virus, Viral Envelope
29 Jan 2015
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Quasi-equivalent interactions: very similar but not identical interactions. Size of capsid is increased by adding more subunits with 6-fold axes. Important for expanding the size of viral particles. They are arranged slightly differently (6-fold axes instead of 5-fold axes) hence the term. Fig 2. 2 (c) all 12 vertices are 5-fold so 12 vertices x 5 subunits = 60 total. Triangulation number (t) t = h2 + hk + k2 where h, k are any two integers, including 0. If we can calculate this we can calculate the total number of proteins present in capsid. Total number of proteins in a capsid = t x 60. Fig 2. 2 (c) example of t = 1 (60 subunits) Fig 2. 4 (a) example of t = 3 (180 subunits) Should be 7 x 60 or 420 subunits. Each subunit binds to 3 nt"s (see that each protein subunit is attached to 3 beads )
