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Piez, Wendell

doi:10.1023/a:1014321125006

Cited by 1 publication

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“…Compared to positive staining patterns, this negative staining dark band corresponds roughly to dark‐band c 1 . The fact that the two staining procedures reveal extra densities for different bands is not contradictory for banding depends on electrical charge axial distribution of the sequenced amino acids in the first case12, 14, 23, 24, 28, 65, 68 and on amino acid bulkiness and/or hydrophobicity in the second 22, 25–27, 29, 31. Rather, this discrepancy supports the view that negative staining dark bands do not reflect a superimposition of positive on negative staining but that they depend on a mechanism intrinsic in negative staining, as has been pointed out already 29, 31…”

Section: Discussionmentioning

confidence: 99%

“…Molecule‐234 amino acid staggering is accepted for collagen fibrils type I6, 7, 14–18, 68 and for type III 18. The above stagger therefore appears to be a common structural feature for the major fibril‐forming collagens, even though support from x‐ray analysis or other conformational analyses is lacking in the case of collagen type II.…”

Section: Discussionmentioning

confidence: 99%

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A model for type II collagen fibrils: Distinctive D-band patterns in native and reconstituted fibrils compared with sequence data for helix and telopeptide domains

2000

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The periodical D‐band pattern is generally considered a unique ultrastructural feature shared by all fibril‐forming collagens, which correlates with the intrafibril, paracrystalline array of tropocollagen monomers. Distinct band patterns have been reported, however, for collagen stained long‐spacing (SLS) crystallites of genetic types I, II, and III. Moreover, D‐band patterns of negatively stained, native type II collagen fibrils were found to be not identical to those of type I in our previous research. Because of (a) these distinctive features, (b) tropocollagen heterotrimeric conditions (type I) vs homotrimeric conditions (type II), and (c) different lengths and poor homology between extrahelical telopeptides, the molecular array or telopeptide conformation within the extensively studied type I collagen fibrils could be not the same as those in the very much less intensively studied type II collagen fibrils. In this investigation, a distinctive positive‐staining D‐band pattern was found for type II collagen fibrils obtained from human cartilages. A fibril model was developed by analyzing actual D‐band patterns, and matching them against simulated patterns based on the primary structure of extrahelical and helical domains in human type II tropocollagen. In particular, a more prominent b1 band was apparent in native type II collagen fibrils than in type I. This distinctive feature was also observed for native‐type collagen fibrils reconstituted from purified type II collagen, i.e., free from associated minor type XI collagen. On modeling possible monomer arrays, the best fit between microdensitograms and simulation traces was found for 234 amino acid staggering, as is also the case for type I collagen fibrils. On comparing this model with an analogous one for type I collagen fibrils, there was a higher intraband distribution of charged residues for band b1 , consistent with the higher electrondensity observed for this band in type II collagen fibrils. N‐ and C‐telopeptide displacement in the model corresponded to D‐locations of a c2 subband, which we named c2.0 , and band a3 , respectively. In simulation profiles, c2.0 ‐like and a3 ‐like peaks mimicked the corresponding peaks in microdensitograms when molecular reversals were adopted at positions 10N–12N, 12C–14C, and 17C–19C for N‐ and C‐telopeptides. Hydrophobic interactions and algorithmic predictions of protein secondary structure, according to Chou and Fasman and Rost and Sander criteria, were consistent with these conformational models, and suggest that an additional molecular reversal may occur at positions 3N–5N. These telopeptide “S‐fold” conformations, interpreted as axial projections of tridimensional conformation, may represent starting points for further investigation into the still unresolved tridimensional conformation of telopeptides in monomers arrayed within type II collagen fibrils. © 2000 John Wiley & Sons, Inc. Biopoly 54: 448–463, 2000

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