title: New insight into the shortening of the collagen fibril D-period in human cornea.
abstract: Collagen fibrils type I display a typical banding pattern, so-called D-periodicity, of about 67 nm, when visualized by atomic force or electron microscopy imaging. Herein we report on a significant shortening of the D-period for human corneal collagen fibrils type I (21 ± 4 nm) upon air-drying, whereas no changes in the D-period were observed for human scleral collagen fibrils type I (64 ± 4 nm) measured under the same experimental conditions as the cornea. It was also found that for the corneal stroma fixed with glutaraldehyde and air-dried, the collagen fibrils show the commonly accepted D-period of 61 ± 8 nm. We used the atomic force microscopy method to image collagen fibrils type I present in the middle layers of human cornea and sclera. The water content in the cornea and sclera samples was varying in the range of .066-.085. Calculations of the D-period using the theoretical model of the fibril and the FFT approach allowed to reveal the possible molecular mechanism of the D-period shortening in the corneal collagen fibrils upon drying. It was found that both the decrease in the shift and the simultaneous reduction in the distance between tropocollagen molecules can be responsible for the experimentally observed effect. We also hypothesize that collagen type V, which co-assembles with collagen type I into heterotypic fibrils in cornea, could be involved in the observed shortening of the corneal D-period.
authors.affiliation: a Department of Solid State Physics, A. Chelkowski Institute of Physics , University of Silesia , Uniwersytecka 4, 40-007 Katowice , Poland.|d Silesian Center for Education and Interdisciplinary Research , University of Silesia , 75 Pułku Piechoty 1, 41-500 Chorzów , Poland.
authors.forename: Maria
authors.initials: M
authors.lastname: Jastrzebska
authors.affiliation: b Faculty of Medicine and Division of Dentistry in Zabrze, Clinical Department of Ophthalmology , Medical University of Silesia , Panewnicka 65, 40-760 Katowice , Poland.|c Department of Biophysics and Molecular Physics, A. Chelkowski Institute of Physics , University of Silesia , Uniwersytecka 4, 40-007 Katowice , Poland.|d Silesian Center for Education and Interdisciplinary Research , University of Silesia , 75 Pułku Piechoty 1, 41-500 Chorzów , Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Tarnawska
authors.affiliation: c Department of Biophysics and Molecular Physics, A. Chelkowski Institute of Physics , University of Silesia , Uniwersytecka 4, 40-007 Katowice , Poland.|d Silesian Center for Education and Interdisciplinary Research , University of Silesia , 75 Pułku Piechoty 1, 41-500 Chorzów , Poland.
authors.forename: Roman
authors.initials: R
authors.lastname: Wrzalik
authors.affiliation: a Department of Solid State Physics, A. Chelkowski Institute of Physics , University of Silesia , Uniwersytecka 4, 40-007 Katowice , Poland.|d Silesian Center for Education and Interdisciplinary Research , University of Silesia , 75 Pułku Piechoty 1, 41-500 Chorzów , Poland.
authors.forename: Artur
authors.initials: A
authors.lastname: Chrobak
authors.affiliation: d Silesian Center for Education and Interdisciplinary Research , University of Silesia , 75 Pułku Piechoty 1, 41-500 Chorzów , Poland.
authors.forename: Michal
authors.initials: M
authors.lastname: Grelowski
authors.affiliation: b Faculty of Medicine and Division of Dentistry in Zabrze, Clinical Department of Ophthalmology , Medical University of Silesia , Panewnicka 65, 40-760 Katowice , Poland.
authors.forename: Edward
authors.initials: E
authors.lastname: Wylegala
authors.affiliation: d Silesian Center for Education and Interdisciplinary Research , University of Silesia , 75 Pułku Piechoty 1, 41-500 Chorzów , Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Zygadlo
authors.affiliation: a Department of Solid State Physics, A. Chelkowski Institute of Physics , University of Silesia , Uniwersytecka 4, 40-007 Katowice , Poland.|d Silesian Center for Education and Interdisciplinary Research , University of Silesia , 75 Pułku Piechoty 1, 41-500 Chorzów , Poland.
authors.forename: Alicja
authors.initials: A
authors.lastname: Ratuszna
mesh_terms: D000328:Adult; D024042:Collagen Type I / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D003315:Cornea / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D018625:Microscopy, Atomic Force; D008875:Middle Aged; D011487:Protein Conformation; D013329:Structure-Activity Relationship
chemical_list: D024042:Collagen Type I
keywords: AFM; D-period; collagen fibril; cornea; topography simulation