Trimers of surfactant protein D gathered from a single image produced by Arroyo et al have been lined up and measured by discontinuous lines sums (to accommodate the curvature of some of the molecules). CRD are on the right hand sides of each of the 9 images, Ntermini on the left. It is clear that the 5-peak grayscale (LUT plot) motif is present on those images with a green spot but not really present on the images with the pink spot — where the Nterminus and the first part (peak) of the collagen-like domain appear as a “bent” or “scrunched” bright (in terms of grayscale) area and they are also significantly different (n=3 56.66nm+/- 3.23 vs n=6 71.82nm +/- 6.6, p=0.008). The selection looks biased (and is) but is based on the number of bright peaks perceived by naked eye. I will plot each and see reevaluate in next post. Also the shortest set have a greater brightness indicating greater height in AFM.

Another interesting thing is that the Ntermini in the trimers is NOT the brightest peak (which it is in all the multimers above that (hexamers, dodecamers, fuzzyballs) and this to me means that there is a side-to-side attachment of the Ntermini… but which looks different than the CRD’s obvious 3-lump images, it looks more like an overlapping splice joint  rather than half lap or side to side joint.