Enzymology :Enzyme specificity-Types & applicationsDr. Rohini C Sane

Enzyme specificity Types of Enzyme specificity

1. Absolute

2. Broad

Absolute Specificity of Enzymes

eg Fumarase & Aspartase exhibits rigid & geometrical specificity

Absolute Specificity of Enzymes :

Enzyme specificity• Absolute Specificity Of Enzymes

Fumarase dose not react with Maleate (cis isomers of Fumarate )

Enzyme specificity

Absolute specificity of enzymes

Aspartase dose not react with D-Aspartate ,OR Maleate –CIS isomer with FUMARATE

Enzyme specificity

Broad Specificity of enzymes

1. eg Chymotrypsin hydrolyses peptide bond (carboxyl group contributed by phenylalanine, Tyrosine, Tryptophan)

2. Intestinal Phosphatase –hydrolysis of esters of phosphoric acid

Broad specificity of ChymotrypsinHydrolysis of peptide bonds by Chymotrypsin

• A1—A2-----------------------------A4 ----A5--COOH

• A1—A2-----------------------------A4 ----A5—COOH

• A1—A2-----------------------------A4 ----A5--COOH

• Site of cleavage by chymotrypsin

PHENYLALANINE

TYROSINE

TRYPTOPHAN

Broad specificity of Trypsin

Lock & Key hypothesis of enzyme specificity

Lock & Key hypothesis of enzyme catalysis

Applications of Enzyme Specificity 1.Lock & key relationship between the substrate & specific area on

the enzyme

2.Substrate structural features

(a) bonding group or functional group

( b) susceptible bond

Enzyme structural features

(a) positioning site Active site

(b) catalytic site

Mapping of enzyme active site-needed for drug designing

Mapping Of Enzyme Active Site

• Substrate of Chymotrypsin = hydrophobic positioning group + susceptible acyl bond

• Active site of Chymotrypsin =positioning group + catalytic site

• Positioning group can be attributed by hydrophobic /aromatic ring of amide ,esters ,amino acids ( Phe,Trp,Tyr )