* Which types of collagen involved in SCURVY? Collagen type I – most abundant of human body (70%). * Where does collagen present? Widely distribute in scar tissue, bone, tendon, skin and internal organs. * What are their functions? Collagen as strong white fibers, stronger than steel wire of the same weight , and as yellow elastic networks (called elastin), usually together with macropolysaccharides, constitutes the connective tissue that keeps membrane strong, creates network and holds our bodies together Mechanism: ( nhờ Đăng chỉnh slide này thêm cái animation như sau: Hiện SCURVY trước, rồi hiện từng dấu mũi tên, hiện mechanism, hiện cái bảng ( không hiện 2 dấu chéo trong bảng), hiện dòng chữ cuối cùng, rồi mới hiện dấu chéo đỏ trong bảng. Here is a figure shown how collagen is synthesized……(chém vô) First, Type I collagen is synthesized by fibroblasts in the endoplasmic reticulum as larger precursors molecules, procollagens, which have large propeptide extensions at both the aminoterminal (chỉ vô đoạn N-terminal propeptide) and the carboxyterminal ( chỉ vô đoạn C-terminal propeptide) ends of the molecule. After secretion into the extracellular space, the propeptides are cleaved off from procollagen by specific proteases, leading to formation of mature type collagen with short non-helical telopeptide regions at both ends of the molecule. ( lúc này chỉ vô đoạn collagen – đã bị cắt mới 2 đầu N-terminal và C-terminal). Then, These telopeptide regions are the primary sites for intermolecular cross-linking, which are important for stabilizing the collagen fibers. The telopeptide lysyl and hydroxylysyl aldehydes are capable of reacting with the residues of other collagen molecules to form immature divalent cross-links. ( chỉ cái vị trí Telo-peptide)
So, does Vitamin C involved in collagen synthesis? Of course because Vitamin C is essential for the building of collagen. The important thing here is Vitamin C acts as an electron donor for three enzymes...
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