MacroPhage

Hi, after long time Today, we will explain Glycosaminoglycans, Proteoglycans and Glycoprotein but before we start, we will make a quick revision for basics of carbohydrates. Revision: Carbohydrates have general formula (CH2O)n , where n ≥ 3. They are classified into monosaccharides (simple sugar such as glucose), disaccharides and polysaccharides. They can also be classified into aldoses (-CHO) and ketoses (-CO) where: Enantiomers are special type of isomerism is found in the pairs of structures that are mirror images of each othe r where the two members of the pair are designated as a D- and an L-sugar. In the D isomeric form, the –OH group on the asymmetric carbon (a carbon linked to four different atoms or groups) farthest from the carbonyl carbon is on the right, whereas in the L-isomer, it is on the left . Cyclization: You can see anomeric carbon in the image (referred by arrow). Alpha anomer where OH on anomeric carbon is trans to

VITAMIN D The D vitamins are a group of sterols that have a hormone-like function . The active molecule , 1,25-dihydroxycholecalciferol ([1,25-diOH-D3], or calcitriol ), binds to intracellular receptor proteins . The most prominent actions of calcitriol are to regulate the serum levels of calcium and phosphorus. Distribution 1-Endogenous vitamin precursor:    7-Dehydrocholesterol , an intermediate in cholesterol synthesis, is converted to cholecalciferol in the dermis and epidermis of humans exposed to sunlight and transported to liver bound to vitamin D–binding protein. 2.Diet:   Ergocalciferol (vitamin D2 ), found in plants , and cholecalciferol ( vitamin D3 ), found in animal tissues , are sources of preformed vitamin D activity. Vitamin D2 and vitamin D3 differ chemically only in the presence of an additional double-bond and methyl group in the plant sterol. Dietary vitamin D is packaged into chylomicrons . [Note: Preformed vitamin D