This is a quick test of the arc angle of the trimeric arms of three different collectins but mostly CL-43. The measures are made from publication(s) from other investigators but for this post, principally from Holmskov et al, 1995 so these are not my micrographs. Each molecule (individually) for CL-43 and bovine conglutinin and SP-D seem to display slightly curved trimeric arm(s) (totally unlike the diagrams of SP-D, conglutinin and CL-43. These diagrams are typically straight lines arranged as X s clearly not right. This discrepancy was something that grabbed my interest). Quickly measured arc angle of CL-43 molecules (n= 35) shows an arc angle of 38.3+/1 1.79. This was not significantly different than a couple of dodecamers of SP-D measured similarly (using the best fit circle and arc length to determine the angle) which was n=11 molecules, x=35.7+/- 1.71. I will add the arc angle of conglutinin molecules and a couple of measures for mutant SP-D from papers published in the scientific literature. But here is the single image (replicated 3 times for different measures of the arc angle of CL-43 as shown in the black lines and degree text in each image. The insets are SP-D and conglutinin, with just one molecule each in that inset. Molecules were rotary shadowed according to the authors M&M.
A paired dataset, now with many more samples of SP-D angles than CL-43 shows the two very nearly the same.
currently: ONLINE calculator gives these values
Surfactant protein-D
(19 dodecamers – 4 arms measured independently)
N1: 75
df1 = N – 1 = 75 – 1 = 74
M1: 38.11
SS1: 10426.67
s21 = SS1/(N – 1) = 10426.67/(75-1) = 140.9
CL-43
(36 measures = 6 dodecamers – 4 arms measured independently)
N2: 35
df2 = N – 1 = 35 – 1 = 34
M2: 38.32
SS2: 3847.39
s22 = SS2/(N – 1) = 3847.39/(35-1) = 113.16
The results are show no significant difference in the arc angle in the collagen portion between these two molecule types. The next thing would be to compare the aa sequences and aa length of the collagen domain of the arms of these two different collectins. In fact with the current dataset…. the SP-D is right on 38.1 degrees just like CL-43. The calculations us each of the four angles per dodecamer as an N so n= “arc angle”
THE FINAL t-test are as follows:
N1: 35
df1 = N – 1 = 35 – 1 = 34
M1: 38.32
SS1: 3847.39
s21 = SS1/(N – 1) = 3847.39/(35-1) = 113.16
Treatment 2
N2: 129
df2 = N – 1 = 129 – 1 = 128
M2: 35.72
SS2: 20437.31
s22 = SS2/(N – 1) = 20437.31/(129-1) = 159.67
WHETHER calculated with the n of SP-D molecules individually (that is 4 per dodecamer – yes there was one molecule where i could only measure the arc angle of three arms) or whether the t test was done using the mean of the arc angles for the dodecamer as N, where n=30 for SP-D, the results were almost identical.
it will be interesting also to see whether conglutinin is similar…