when do we say glycosidic is alpha and beta
Answers
Answer:
1,4 glycosidic bond
Alpha and Beta Glycosidic Bonds.png1,4 glycosidic bond bonds are formed due to condensation reactions between a hydroxyl oxygen atom on carbon-4 on one sugar and the α-anomeric form of C-1 on the other[1].
The two monosaccharides (monomers, a molecule that can be bonded to other identical molecules to form a polymer) form a disaccharide (2 monomers bound together) and subsequently a polysaccharide (polymers, or many units of sugars). A condensation reaction is when water is eliminated to form a simple molecule. Later hydrolysis by water molecules will reform the two original monosaccharides.
The 1,4 glycosidic bond is formed between the carbon-1 of one monosaccharide and carbon-4 of the other monosaccharide. There are are two types of glycosidic bonds - 1,4 alpha and 1,4 beta glycosidic bonds. 1,4 alpha glycosidic bonds are formed when the OH on the carbon-1 is below the glucose ring; while 1,4 beta glycosidic bonds are formed when the OH is above the plane[2]. When two alpha D-glucose molecules join together a more commonly occurring isomer of glucose compared to the L-glucose, form a glycosidic linkage, the term is known as a α-1,4-glycosidic bond
Answer:
It depends on the conformation of the -OH group on the anomeric carbon.
Example: Glucose is a 6 carbon monosaccharide Biologically, carbohydrates are preferred in D conformation (whereas amino acids in L). When you draw Glucose in pyranose form you draw the ch2OH on carbon 5 of the pyranose “up” for D. Therefore, if you were to draw the -OH group on C1 of the pyranose cis to that Ch2Oh it is beta and if you draw it trans to that, it is alpha. So in a glycosidic linkage between two monosaccharides, the glycosidic linkage name would depend on the conformation of the OH on the first sugar of the linkage.
I felt like i just rambled on but i hope i helped a bit