chemical properties of protein

Chemical properties of proteins and explanation simply

1. Chemical properties of protein By saddam hussein

2. INTRODUCTION PROTIENS CHEMICAL PROPERTIES OF PROTEINS

3. INTRODUCTION SADDAM HUSSEIN BS FOOD SCIENCE AND TECHNOLOGY MINHAJ UNIVERSITY, LAHORE

4. proteins Proteins  are large, complex molecules that play many critical roles in the body.   Proteins  are made up of hundreds or thousands of smaller units called amino acids, which are attached to one another in long chains . Proteins are classified on the base of Structure

5. Chemical properties of proteins

6. Conti…

7. Hydrolysis Proteins are hydrolyzed by a variety of hydrolytic agents . By acidic agents: Proteins, upon hydrolysis with conc. HCl (6–12N) at 100–110°C for 6 to 20 hrs, yield amino acids in the form of their hydrochlorides .  By alkaline agents: Proteins may also be hydrolyzed with 2N NaOH .

8. Reactions involving COOH Group Reaction with alkalies (Salt formation ) Reaction with alcohols (Esterification ) Reaction with amines

9. Arginine Residue The arginine residue of proteins reacts with α- or β- dicarbonyl compounds to form cyclic derivatives. The nitropyrimidine derivative absorbs at 335 nm. The arginyl bond of this derivative is not cleaved by trypsin but it is cleaved in its tetrahydro form, obtained by reduction with NaBH4. In the reaction with benzil , an iminoimidazolidone derivative is obtained after a benzilic acid rearrangement .

10. Glutamic and Aspartic Acid Residues These amino acid residues are usually esterified with methanolic HCl . There can be side reactions, such as methanolysis of amide derivatives or N,O-acyl migration in serine or threonine residues - Diazoacetamide reacts with a carboxyl group and also with the cysteine residue Amino acid esters or other similar nucleophilic compounds can be attached to a carboxyl group of a protein with the help of carbodiimide

11. Cystine Residue Cleavage of cystine is possible by a nucleophilic attack: The nucleophilic reactivity of the reagents decreases in the series: hydride> phosphite > alkanethiol > aminoalkanethiol > thiophenol and cyanide> sulfite> OH−> p- nitrophenol > thiosulfate > thiocyanate. -Complete cleavage with sulfite requires that oxidative agents (Cu2+) be present and that the pH be higher than 7:

12. CystEine Residue A number of alkylating agents yield derivatives which are stable under the conditions for acidic hydrolysis of proteins. The reaction with ethylene imine giving an S- aminoethyl derivative and, hence, an additional linkage position in the protein for hydrolysis by trypsin. Iodoacetic acid, depending on the pH, can react with cysteine, methionine, lysine and histidine residues