Enzymes are biological catalysts, usually proteins (some are RNA – ribozymes), that speed up chemical reactions in living organisms without being consumed in the process. Key Features of Enzymes: Catalysts: Increase the rate of biochemical reactions by lowering the activation energy. Specificity: Each enzyme is highly specific to its substrate (the molecule it acts on). Active Site: The region of the enzyme where the substrate binds and reaction occurs. Reusable: They are not consumed in the reaction, so they can be used repeatedly. Regulated: Their activity can be enhanced or inhibited, ensuring metabolic control. Efficient: Reactions that would take years can occur in milliseconds with enzymes. Structure: Mostly proteins with a unique 3D structure. Some require cofactors (metal ions like Zn²⁺, Mg²⁺) or coenzymes (organic molecules like NAD⁺, FAD, vitamins). Types (based on reaction): Oxidoreductases – oxidation/reduction reactions (e.g., dehydrogenases). Transferases – transfer functional groups (e.g., kinases). Hydrolases – hydrolysis reactions (e.g., lipases, proteases). Lyases – add/remove groups without hydrolysis (e.g., decarboxylases). Isomerases – rearrange atoms within a molecule (e.g., mutases). Ligases – join molecules using ATP (e.g., DNA ligase). Clinical Importance: Enzyme levels in blood are used as biomarkers for diseases (e.g., elevated ALT/AST in liver disease, CK-MB in myocardial infarction). Many drugs act as enzyme inhibitors (e.g., statins inhibit HMG-CoA reductase). 👉 Do you want me to make a short exam-oriented description (2–3 lines), or a detailed one with examples for your MD Biochemistry Introduction Definition Historical background (Pasteur, Buchner, Sumner, etc.) Importance in life processes 2. General Characteristics of Enzymes Catalytic power Specificity Efficiency Reusability Regulation 3. Structure of Enzymes Protein nature Apoenzyme and holoenzyme Active site: features & models (lock and key, induced fit) Cofactors, coenzymes, prosthetic groups 4. Classification of Enzymes IUBMB classification – six main classes with examples Enzyme Commission (EC) number system 5. Mechanism of Enzyme Action Substrate binding Transition state theory Lowering activation energy Catalytic strategies (acid–base catalysis, covalent catalysis, metal ion catalysis) 6. Kinetics of Enzymes Michaelis–Menten equation Lineweaver–Burk plot Km and Vmax significance Turnover number (Kcat) Factors affecting enzyme activity: temperature, pH, substrate concentration, enzyme concentration, inhibitors 7. Enzyme Inhibition Reversible inhibition (competitive, non-competitive, uncompetitive, mixed) Irreversible inhibition (suicide inhibitors, poisons) Clinical relevance (cyanide, organophosphates, drugs like statins, aspirin) 8. Regulation of Enzyme Activity Allosteric regulation Feedback inhibition Covalent modification (phosphorylation, acetylation) Isoenzymes Induction and repression of

1. CLINICAL ENZYMOLOGY
Dr. Mohammad Azharuddin Mulla
Vallabhbhai Patel Chest Institute Delhi

2. vDIAGNOSTIC
vTHERAPEUTIC
vANALYTICAL USES OF ENZYMES

3. CLINICAL ENZYMOLOGY
DIAGNOSTIC USES THERAPEUTIC USES ANALYTICAL/LAB USES
Ø Diagnosis
Ø Monitoring
Ø Treatment Ø Laboratory Analysis

4. ENZYMES
PLASMA FUNCTIONAL
ENZYMES
PLASMA NON-FUNCTIONAL
ENZYMES
• Plasma Specific
• Most are synthesized in liver, released into the plasma
• Ex:
ü Coagulation factors
ü Complement factors
ü Lipoprotein Lipase
ü Ceruloplasmin
ü Renin
ü Cholinesterase
• Plasma Non-Specific
• Derived from cells of organs and tissues
• Ex:
ü Creatine Kinase
ü Lactate dehydrogenase
ü Alkaline Phosphatase
ü Aspartate Aminotransferase (AST)
ü Alanine Transaminase (ALT)
ü Etc….

5. Plasma Non functional Enzymes
Disease states of tissues
Hypoxic of infective insults
Excessive synthesis or
induction with
overflow into plasma
Vigorous Excercise
Decreased renal clearance

6. DIAGNOSTIC USES OF ENZYMES
CARDIAC
PANCREAS
PROSTATE
BONE
LIVER
BILIARY TRACT
MUSCLE
ü AMYLASE
ü LIPASE
ü ACP,
ü PSA
ü ALP: PRE !
ü CK-MB
ü AST
ü LDH
ü AST
ü ALP
ü GGT
ü ALT
ü 5’NT
ü GGT
ü CK-MM
ü AST
ü ALDOLASE
OTHERS
ü G-6-PD
ü CHOLINESTERASE
ü CERULOPLASMIN

7. ENZYME PROFILE IN CARDIAC DISEASE
• Detection of AMI and minor myocardial injury

8. ENZYME PROFILE IN CARDIAC DISEASE

9. Non Enzymatic/Enzymatic Cardiac markers:

10. ENZYME PROFILE IN LIVER DISEASES
Markers of
Hepatocellular Injury
Markers of
Cholestasis
v Alanine Transaminase (ALT)/SGPT
v Aspartate Transaminase (AST)/SGOT
v Alkaline Phosphatase (ALP)
v !-glutamyl transferase (GGT)
v 5’ Nucleotidase

11. ENZYME PROFILE IN LIVER DISEASES
ALANINE TRANSMINASE ASPARTATE TRANSAMINASE
Site Liver- Cytosol Liver, Heart, Skeletal muscle, Cytosol,
Mitochondria
Normal ref range 5-40 U/L 5-35 U/L
Marked Increase (300-1000 U/L) Severe viral hepatitis, toxic hepatitis Severe hepatitis, toxic hepatitis
Mild to Mod Increase (50-100 UL) Biliary tract obst, alcoholic hepatitis Alcoholic hepatitis, Chronic active
hepatitis, hepatic metastasis
Non Hepatic conditions ----- MI, skeletal muscle disorders
Both ALT and AST are increased in Liver disease, but ALT>AST
Normal AST/ALT ration is <1
Ration >2 is seen in alcoholic hepatitis, because
ü due to reduction of hepatic AST and
ü increased release of AST from mitochondria

12. Alkaline Phosphatase: ALP- Markers of Obstructive liver disease
Isoenzymes Site Condition
Alpha-1 ALP Epithelial cells of biliary
canaliculi
Obstructive Jaundice
Alpha -2 (Heat Liable) Hepatic cells Hepatic disease
Alpha-2 (Heat stable) Placental origin Pregnancy
Pre-Beta Bone Bone diseases
Gamma Intestinal cells Ulcerative colitis
Leucocyte ALP CML (↓) Lymphomas (↑)

13. Normal ref range of ALP: 30-115 U/L
Moderate(2-3 times)
ü Hepatic diseases
ü Infective hepatitis
ü Alcoholic hepatitis
ü Hepatocellular carcinoma
Very High (10-12 times)
ü Extra hepatic Obstruction
ü Obstructive jaundice
ü Intra-hepatic cholestasis
ü Viral hepatitis
ü Drugs (chlorpromazine)
Drastically High (10-25 times)
ü Bone diseases
ü Paget’s disease
ü Rickets, Osteomalacia
ü Osteoblastoma
ü Mets Ca of bone

14. Gamma-Glutamyl transferase: GGT- Markers of Obstructive liver disease
üIt is seen in Liver, Kidney, Intestine
üRef range: 5-40 U/L
üSensitive biomarker for the recognition of alcohol abuse and ALD
even when other LFT are within normal limits
üSignificantly increased in obstructive jaundice

15. 5’ Nucleotidase -Markers of Obstructive liver disease
üEctoenzyme present on cell membrane
üRef range: 2-10 U/L
üModerately increased in biliary obstruction
üMore specific for obstructive liver disease

16. ALP GGT Condition
Mild or moderately elevated Elevated Hepatic or Biliary disease
Highly elevated Elevated Biliary disease only
Elevated Normal Bone disease
Normal Elevated Alcohol abuse

17. Enzyme profile in Muscle disease
Creatine Kinase
(CK-MM)
Aspartate Transaminase Aldolase
Marked increased in
Muscle disease
↑ in muscle disease
Not specific
Earliest enzyme to rise but
not specific

18. Enzyme Profile in Pancreatic disease
AMYLASE LIPASE (More specific than Amylase)
Produced by Pancreas (P-type) & Salivary glands (S-
type)
Present in Pancreatic secretions
Normal ref range: 50-120 U/L Normal Ref range: 0.2- 1.0 U/L
↑ in Acute Pancreatitis (1000 times) ↑ Acute Pancreatitis
Peak: B/w 5-12 hours after onset
Returns to normal within 2-4 days after acute phase
has subsided
Persists for 7-14 days
Elevated longer than amylase
Moderate ↑: Chronic Pancreatitis, Mumps, Pancreatic
duct obstruction
Not increased in mumps
Lipase estimation has advantages over amylase
Moderate ↑ in Ca pancreas, Biliary disease

19. Enzyme Profile in Bone diseases
vALP: pre-!
üDrastically high (10-25 times)
üBone diseases
• Paget’s disease
• Rickets, Osteomalacia
• Osteoblastoma
• Metastatic carcinoma of bone

20. Enzyme profile in Prostate disease
vACID PHOSPHATASE:
üHydrolyses Phosphoric acid ester at pH between 4 & 6
üSecreted by prostate cells, RC, platelets and WBC
üProstate isoenzyme is inactivated by tartaric acid
üNormal ref range ACP: 0-0.6 U/L
üTotal ACP:
§ ↑ in prostate cancer
§ ↑↑ in bone metastasis of prostate cancer
• Useful for follow up of treatment of prostate cancers
• Prostate acid phosphatase: Important tumor marker

21. Enzyme profile in Prostate disease
vPROSTATE SPECIFI ANTIGEN:
• It is not an enzyme but Glycoprotein, with mild protease activity
• Produced from secretory epithelium of prostate gland
• Normally secreted into seminal fluidà liquefaction of seminal
coagulum
• Reliable marker for prostate cancer
• PSA is a tumor marker: detect stage & monitor treatment of prostate
cancer
• PSA is better predictor than prostatic acid phosphatase for diagnosis of
prostate cancer

22. Other Enzymes
vCHOLINESTERASE
• Acetylcholinesterase (True ChE/ Type I ChE)
+ Nerve endings/RBCs
• ChE in RBCs: determine exposure in person working with
organophosphorus insecticides (Parathion)
• Irreversibly inhibit ChE in RBCs
vPSEUDOCHOLINESTERASE:
• (Type II ChE: Nonspecific: hydrolyze acyl esters)
+ Liver cells

23. vGLUCOSE-6-PHOSPHATE DEHYDROGENASE:
• Enzyme of HMP pathway
• ↓ G-6-P-D associated with drug induced hemolytic anemia

24. vCERULOPLAMIN:
• Ferroxidase
• Acute phase protein
• ↑in all inflammatory conditions, collagen diseases, malignancies
• Normal Ref range: 25-50 mg/dL
• <20mg/dL: pathognomic of Wilson’s hepatolenticular degeneration
• Copper toxicity

26. Enzymes in other body fluids:
ENZYME CLINICAL SIGNIFICANCE
Adenosine deaminase (ADA) in pleural fluid ↑↑ Tubercular pleural effusion but not in Malignant
effusion
LDH in pleural/ascitic fluid ↑↑ Malignant tumor ( Not diagnostic, as enzyme is
not tissue specific)

27. Therapeutic Uses:
ENZYME USES
Streptokinase / Urokinase Lysis of intravascular blood clot
Recombinant tissue prothrombin activator (rtPA) Lysis of clot (esp. cerebrovascular thrombolysis)
Asparaginase Acute Lymphoblastic Leukemia
Streptodornase DNAse, applied locally
Pancreatin (trypsin & Lipase) Pancreatic insufficiency
⍺-1 antitrypsin AAT deficiency, Emphysema
Papain Anti-inflammatory agent

28. Analytical uses of enzymes
Enzyme as reagent Uses
Glucose oxidase and peroxidase Glucose
Cholesterol oxidase and peroxidase Cholesterol
Urease Urea
Uricase Uric Acid
Hexokinase and G-6-PD Creatine Kinase
Lipase, Glycerol phosphate dehydrogenase Triacylglycerol
Lactate dehydrogenase Lactate
Alcohol dehydrogenase Ethanol

29. Analytical uses:
vGenetic engineering
• Restriction endonucleasesà Gene transfer, DNA fingerprinting
• Taq DNA polymeraseà Polymerase chain reaction
vIndustrial Uses:
Enzymes Uses
Renin Cheese preparation
Glucose Isomerase Production of high fructose syrup
Alpha amylase Food industry
Proteases Washing Powder

30. THANK YOU