welcome to another biochemistry 101 in this video we are going to learn about fischer and hayworth projection formulas which is which how do you designate the d and l enantiomers this particular method of drawing glyceraldehyde is the basis for what we call the fissure projections in fissure projections a carbon atom seats at each intersection of a vertical and horizontal line the horizontal lines represent bonds pointing toward the viewer and the vertical lines are for bonds pointing away from the viewer so how do we know which is the t enantiomer and the l enantiomer let us again have glyceraldehyde as our example the carbon with the asterisk is our chiral center since it has one stereocenter or chiral center it exists in two stereoisomeric forms or as a pair of enactures the pair of enantiomers can be represented in wedge and dashed line notation and also as fischer projections the handedness will then be determined by the orientation of the hydroxyl group at the chiral carbon farthest from the aldehyde group or the hydroxyl carbon on the highest numbered chiral carbon in the case of glyceraldehyde since there is only one chiral carbon atom that will be the basis so it will be designated as either the glyceraldehyde when the which group is on the right and l glycerol behind when the o h grew is on the left let us look at other examples this is glucose a six carbon monosaccharide so in this case there are multiple chiral centers present carbons number two three four and five are all chiral carbons in this case we take a look at the last chiral carbon or the highest numbered chiral carbon which has carbon number five where is the oh group located it's on the right side which means that this is the glucose and its mirror image is l glucose and if you will notice the o h group on l glucose is on the left side another example would be this compound 2-3-4-trihydroxy butanol a monosaccharide that has two chiral centers as indicated by the asterisk this means that this monosaccharide has four stereoisomers or two pairs of enactures if we would look at each monosaccharide from this pair of enantiomers the carbon chain is numbered starting at the carbonyl group end of the molecule which is carbon number one and the highest numbered chiral center is used to determine the d or l configuration if compounds a and b are in nanomerry pair the same with compounds c and b which are also a natural anatomic bear what do you think is the relationship between compound a and c they are diastereomers now that we learned about mirror images chirality and handedness it is quite amazing to know that in our bodies and in most of the biological world only one from the two mirror image or a pair of enantiomer can be found so for an instance the common sugars are members of the d family whereas for all common amino acids that make up our proteins are members of the l family pharmaceutical chemists are actually becoming more and more concerned with the stereochemical purity of the drugs we take let us consider a few examples in the 1960s or in 1960 the drug thalidomide was commonly prescribed in europe as a sedative however during that year hundreds of women who took thalidomide during pregnancy gave birth to babies with severe birth defects it turned out that thalidomide was actually a mixture of two enactures one is a sedative as being advertised and sold and the other was a teratogen which is a chemical that causes birth defects another example would be the antihistamines have you experienced to be drowsy or sleepy after taking an antihistamine for colds or allergies this is actually a side effect of antihistamines being a mixture of a naturals one causes drowsiness while the other is a good decongestant another one would be the pair of enantiomers of carbon which is present in the oils that give scent to spearmint and caraway seeds ordeal our old receptors in our nose detect this enantiomers as two different odors thus our senses of smell and taste are responsive to chirality of molecules ibir-profan is another example it is also being currently sold as a mixture of enactromers but one is a much more effective analgesic than the other so the taste the smell and the biological effects of drugs in the body all depend on the stereochemical form of compounds and their interactions with cellular enzymes and receptors so because of this chemists are actively working to devise methods of separating the isomers in pure form alternatively methods for stereospecific synthesis are being sold by preparing pure stereoisomers the biological activity of a compound can be much more carefully controlled and this will lead to safer medications now let us take a look into hayworth projection formulas hayworth projection formulas are two-dimensional structural notations that specify the three-dimensional structure of a cyclic form of a monosaccharide now how do we write hayworth projection formulas now here we have d glucose in reality the open chain form of glucose as depicted by this fischer projection is present in very small concentrations in the cells it exists in cyclic forms under physiological conditions because the carbonyl group at carbon 1 of glucose reacts with a hydroxyl group at carbon number five forming a six-membered ring when the carbonyl group of the aldehyde portion of the glucose molecule reacts with a carbon 5-hydroxyl group the product is a cyclic intramolecular hemiacetal so for d-glucose two isomers can be formed from this reaction and these are called alpha and beta betancos take note also that in this process the carbonyl carbon which is carbon number one becomes a chiral center in this process which gives the alpha and the beta forms of glucose this chiral center is what we call the anomeric carbon the hemiacetal is highlight then in yellow the d or l form of a cyclic monosaccharide is determined by the position of the terminal ch2h group on the highest numbered ring carbon atom so in the d form this group is positioned above the ring in the l form the terminal ch2h group is positioned below the ring the alpha or beta configuration is determined by the position of the o h group on carbon 1 relative to the ch2oh group that determines d or l monosaccharide so in the beta configuration both groups point toward the same direction either both upward or both downward the alpha configuration has a two groups position in opposite directions so here we have the beta d monosaccharide with both the ch2oh and oh group pointing upwards and then next we have the alpha d monosaccharide which has the ch2h pointing upwards and the o h group which is below the ring the beta l monosaccharide has both the ch2oh group and the oh group pointing downwards when alpha or beta configuration does not matter though each group on carbon number one is placed in a horizontal position and a wavy line is used as the bond that connects it to the ring