180 likes | 925 Views
膠原蛋白 Collagen. 第二組 李建毅 秦家翊 盧星翰 劉修勳 張豪訓 劉浩文 張博堯 陳威宇 張菡芸. Structure : Primary sequence :Gly-X-Pro(HyPro) Monomer( alpha chain)=> left handed helix,3 a.a. per turn Trimer:coiled-coil => stabilized by H-bond
E N D
膠原蛋白 Collagen 第二組 李建毅 秦家翊 盧星翰 劉修勳 張豪訓 劉浩文 張博堯 陳威宇 張菡芸
Structure: Primary sequence :Gly-X-Pro(HyPro) Monomer( alpha chain)=> left handed helix,3 a.a. per turn Trimer:coiled-coil => stabilized by H-bond crosslink between triple helixes(disulfide bond) Tendons,cartilage,cornea,skin,bone Function:Provide tensile strength Collagen
The increasingly rigid and brittle charater of aging connective tissue results from accumulated covalent cross-links in fibrils
Covalent Cross-Links共價連接 Tropocollagen結合成collagen之微纖維(microfibril) ,最初是藉鏈內的氫鍵在穩定,後來則靠螺旋內和螺旋間形成的共價鍵來穩定。 Lysine lysyl oxidase Hydroxylysine aldehyde 上的ε胺基 醛纇
Covalent Cross-Links共價連接 和其他aldehyde產生醛醇縮合產物 aldehyde 和其他未被氧化的ε胺基形成 Schiff base 這些反應再經過進一步的化學重排後,會形成穩定的共價性鍵結,對collagen的穩定度有重要影響
Menke’s disesaes • X染色體上的基因變異使得銅的代謝異常 • 結果:這個疾病常發生在男性嬰兒身上(大家可以回想血友病的遺傳情形) • 因lysyl oxidase需要銅作為輔助因子,當缺乏銅時,會影響到lysyl oxidase的活性,令collagen的連結受到影響。 • 症狀:毛髮捲曲 生長停滯
Osteogenesis imperfecta • 俗名:玻璃娃娃、成骨不全症 • 症狀:骨骼不夠堅硬、發育不全 • 病因:遺傳疾病造成collagen不足或不全 • Osteogenesis imperfecta(II)
骨骼與膠原蛋白 • 骨骼中的蛋白質約有80%左右是膠原蛋白 • 佔骨骼總重量的20%左右 • 膠原蛋白的特徵氨基酸羥基脯氨酸(hydroxyproline)是血漿中運輸鈣到骨細胞的運載工具
Ehlers-Danlos syndrome Ehlers-Danlos syndrome (EDS) refers to a group of inherited disorders that affect your connective tissues — primarily your skin, joints and blood vessel walls. 一般症狀 • Loose, unstable joints • Highly elastic, velvety skin
Causes • A variety of genetic alterations (mutations) • 遺傳方式:顯性遺傳、隱性遺傳、性聯遺傳 突變的基因無法正常合成下列蛋白質: • Proteins that are used to assemble different types of collagen. • Proteins that process or interact with collagen.
關節與膠原蛋白 • 軟骨保護關節避免磨損 • 軟骨由水,醣蛋白、膠原蛋白級軟骨細胞組成 • 膠原蛋白變少、醣蛋白內含物減少>關節炎
Scurvy(壞血病) symotioms • blood vessels ruptured and blood wept from hair follicles. • Blotches appeared all over the body • bruise or exertion could result in internal bleeding. • Arms and legs would swell up • wounds, even small scratches, would not heal. • Gums reddened, receded, and blackened until teeth loosened and fell out 病因 • The role that Vit.C plays in the formation of ligand. • A collagen is constructed by many many tripeptides. Gly-X-Y • And the most stable form is Gly-Pro-4-Hyp.
# The proline ring is normally found as a mixture of the two puckered conformation. # Cr-endo (Pro residue in the X position requires the Cr-endo conformation, and introduction of 4-Hyp can destabilized the helix.) # Cr-exo (The Y positions are in the Cr-exo conformation,and it’s this conformation that is enforced by the hydroxyl substitution at C-4 in 4-hydroxyproline ) # The inability to hydroxylate the Pro at Y positions when Vit. C absent leads to collagen instability and the connective tissue problems seen in scurvy.
Prolyl hydroxylase is an enzyme involved in the production of collagen, acting to hydroxylateproline to hydroxyproline(Hyp).It requires vitamin C(ascorbic acid) as a co-factor. • The process requires ascorbic acid as a reductant to restore enzyme activity . •