Question

14) Which of the following amino acids will by cation-exchange chromatography? following amino acids will be retained longest in the column when sepa Η serne HO-CH-C-COO v. Lysine H3N-CH2CH2CH2CH2CH-co NES NH V. Phenylalanine CH-C–COOH II. Alanine CH3-C-Coo II. Cysteine HS-CH-c-coo® NE 15) What is the product obtained from mild oxidation of the thiol shown below? mild 2R-SH oxidation A) R-S- R B) R-OH C) R-S-S-R DR-OO- RE ) R-S-OH 16) Which bond in the following compound is a peptide bond? 1 211 3 4 NH CHO NCHC R HR AIB)2 C3 D4 E) 5 17) When a disulfide bond is formed, the compound containing this new bond has been A) hydrolyzed B) dehydrated C) electrolyzed D) oxidized E) reduced 18) Explain the chemistry behind giving a "permanent" to a head of hair.

Answer 1

beeause it has tvo chage in its side daain Lysine 05.00 05.0 Eve. mild Oxidation R-S-S-R Ce) 2 R-SH 07.00 N and is peptide Loend 17DY Oxidized (loss it His exidatien NOTES:

Hair is made mostly of a protein called keratin, which is also present in nails. In hair, keratin molecules are arranged in straight bundles. These bundles are held together by disulphide bonds (-S-S-), which give strength to the hair. Disulphide bonds are made by the amino acid called cysteine. The cysteine of one keratin molecule forms a disulphide bond with the cysteine of the neighbouring keratin molecule. The more disulphide bonds there are in a strand of hair, the straighter it is Ammonium thioglycolate: the perm salt Ammonium thioglycolate (HSCH2CO2NH4) is a compound that can break disulphide bonds. This is because it contains a thiol group (-SH). The thiol group replaces one of the sulphur atoms in the disulphide bond, like this: Keratin-S-S-keratin 2HS-CH2CO2NH>-HO2CH2CS-SCH2CO2H 2NH3 2HS-keratin When the disulphide bond is broken, the keratin bundles come apart, and hair is weakened Ammonium thioglycolate is therefore used widely in beauty parlours when customers want their hair re-styled. However, if you use too much of it, or if the reaction is left for too long, you could end up going bald. So do not, ever, try it at home!