Protein metabolism mind map

 

PROTEIN METABOLISM – COMPLETE REVISION NOTES

1. METABOLISM OF AMINO ACIDS

🔹 A. Transamination

Transfer of amino group from amino acid → keto acid

Enzymes: Transaminases

⭐ Salient Features:

Requires coenzyme: Pyridoxal phosphate (PLP)

Occurs in pairs:

Alanine transaminase (ALT)

Aspartate transaminase (AST)

No free NH₃ released

Reversible process

Helps in:

Synthesis of non-essential amino acids

Gluconeogenesis

🔹 B. Deamination

Removal of amino group → helps in urea formation

Types:

1. Oxidative Deamination

Substrate: Glutamate

Enzyme: Glutamate dehydrogenase

Products:

α-ketoglutarate

NH₃

Site: Liver mitochondria

Coenzyme: NAD⁺

2. Reductive Deamination

Removal of amino group by reduction

Substrate: Keto acids / Imino acids

Enzyme: Reductase

Product: NH₃ released

Coenzyme: NADPH

2. TRYPTOPHAN METABOLISM

🔹 Features:

Essential amino acid

Contains β-indole ring

🔹 Pathways:

1. Kynurenine Pathway

Steps: Tryptophan

→ N-formylkynurenine

→ Kynurenine

→ 3-hydroxykynurenine

→ 3-hydroxyanthranilic acid

Clinical:

Pellagra → 3 D’s:

Dermatitis

Diarrhea

Dementia

Products:

Melatonin (sleep regulation)

2. Serotonin Pathway

Steps: Tryptophan

→ 5-hydroxytryptophan

→ Serotonin

Functions:

Mood regulation

Depression link

3. PHENYLALANINE & TYROSINE METABOLISM

🔹 Characteristics:

Aromatic amino acids

🔹 Conversion:

Phenylalanine

→ Tyrosine

Enzyme: Phenylalanine hydroxylase

Converts essential → non-essential amino acid

🔹 Functions of Tyrosine:

Melanin synthesis

Thyroid hormone synthesis

Catecholamine synthesis

🔹 Tyrosine Degradation Pathway:

Tyrosine

→ p-Hydroxyphenylpyruvate

→ Homogentisate

→ Maleylacetoacetate

→ Fumarylacetoacetate

→ Fumarate + Acetoacetate

Final Fate:

Fumarate → TCA cycle → Glucose

Acetoacetate → Fat

4. UREA CYCLE

🔹 Key Points:

End product of protein metabolism

80–90% nitrogen excreted via urine

🔹 Steps:

CO₂ + NH₄⁺

→ Carbamoyl phosphate

(Enzyme: Carbamoyl phosphate synthetase)

🔸 Uses 2 ATP

Carbamoyl phosphate + Ornithine

→ Citrulline

(Ornithine transcarbamoylase)

Citrulline

→ Argininosuccinate

(Argininosuccinate synthetase)

🔸 Uses 1 ATP

Argininosuccinate

→ Arginine + Fumarate

(Argininosuccinase)

Arginine

→ Urea + Ornithine

(Arginase)

🔹 Important Points:

Total energy: 4 ATP used

Fumarate enters:

TCA cycle

Gluconeogenesis

Ornithine is regenerated (cycle continues)

🔥 QUICK SUMMARY (EXAM REVISION)

Transamination → No NH₃, reversible

Deamination → NH₃ released → Urea

Tryptophan → Serotonin + Kynurenine → Pellagra

Phenylalanine → Tyrosine → Hormones & pigments

Urea cycle → Detoxifies ammonia → Uses 4 ATP

Mind map of lipid metabolism

 

🧠 LIPID METABOLISM – Colorful Handwritten Mind Map

🧠 LIPID METABOLISM

                               

🔴 1. Fatty Acid Oxidation (β-Oxidation)

Occurs in mitochondria

Steps

1️⃣ Activation

Fatty acid + CoA + ATP

→ Fatty acyl-CoA

(enzyme: Acyl-CoA synthetase)

2️⃣ Transport

Carnitine carrier system

3️⃣ β-Oxidation Cycle

• Dehydrogenation → FADH₂ formed

• Hydration

• Oxidation → NADH formed

• Cleavage → Acetyl-CoA

Energetics (Palmitate)

7 FADH₂ → 10.5 ATP

7 NADH → 17.5 ATP

8 Acetyl-CoA → 80 ATP

✔ Total = 108 ATP

✔ Net = 106 ATP

🟠 2. Cholesterol Biosynthesis

Location: Cytosol of liver cells

Pathway

Acetyl-CoA

⬇

HMG-CoA

⬇

Mevalonate

⬇

Isoprene units (IPP + DPP)

⬇

Squalene

⬇

Cholesterol

Requirements

18 Acetyl-CoA

36 ATP

16 NADPH

Uses

✔ Bile acids

✔ Steroid hormones

✔ Vitamin D

🟡 3. Lipoproteins

Lipoprotein = Lipid + Protein

Types

Chylomicrons

Transport dietary fat

VLDL

Transport endogenous triglycerides

LDL

Transport cholesterol to tissues

HDL

Reverse cholesterol transport

Lipoprotein Degradation

1️⃣ Lipoprotein + LPL enzyme

2️⃣ Triglyceride hydrolysis

3️⃣ Fatty acid uptake

4️⃣ Chylomicron remnant formation

5️⃣ Uptake by liver

🟢 4. Ketone Bodies

Types

Acetoacetate

β-Hydroxybutyrate

Acetone

✔ Water soluble

✔ Alternative energy source

Ketogenesis (Liver)

2 Acetyl-CoA

⬇

Acetoacetyl-CoA

⬇

HMG-CoA

⬇

Acetoacetate

⬇

Acetone + β-Hydroxybutyrate

Use

During fasting/starvation

Overproduction

Ketonuria / Ketoacidosis

🔵 5. Fatty Liver

Normal liver lipid ≈ 5%

Cause

Excess triglyceride accumulation

Reasons

Increased TG synthesis

Decreased lipoprotein formation

Alcohol / metabolic disorders

🟣 6. Atherosclerosis

✔ Thickening and hardening of arteries

✔ Due to lipid deposition

Result

⬆ Risk of

Coronary heart disease

Heart attack

✅ Memory Trick for Lipid Metabolism Topics

"F C L K F A"

F → Fatty acid oxidation

C → Cholesterol synthesis

L → Lipoproteins

K → Ketone bodies

F → Fatty liver

A → Atherosclerosis

Mind map of carbohydrates metabolism

 

For TCA cycle menomic is used 

C                citrate 

I                isocitrate 

Alpha.      Ketoglutarate 

S.              Succinnyal coa 

S.              Succinate 

F.              Fumarate 

M.            Malate 

O.            Oxyloacetate 

For glycolysis 

Good                        Glucose

Girls                         Glucose-6-phosphate

 Find                         Fructose-6-phosphate

Friends                    Fructose-1,6-bisphosphate

Don't                        Dihydroxyacetone phosphate

  Get                         Glyceraldehyde-3-phosphate

 Big                           1,3-Bisphosphoglycerate

 Problems               3-Phosphoglycerate

  Please                    2-Phosphoglycerate

  Please                   Phosphoenolpyruvate

  Please                    Pyruvate

Mind map of protein

 

Essential amino acid menmonic 

PVT TIM HALL

P – Phenylalanine

V – Valine

T – Tryptophan

T – Threonine

I – Isoleucine

M – Methionine

H – Histidine

L – Leucine

L – Lysine

Ploysaccharide mind map for medical student

 

Disaccharides mind map for medical student

 

                         ENZYMES 

Mind ma 

ENZYMES — SHORT NOTE (Exam Oriented)

Reference: Satyanarayan

Definition-Enzymes are biological catalysts, mostly proteins, that speed up biochemical reactions without being consumed.

Key Characteristics

Highly specific for substrates

Lower activation energy

Remain unchanged after reaction

Active at optimum pH & temperature

Mostly globu

Some require cofactors

Classification of Enzymes (IUBMB)

Oxidoreductases – Redox reactions

Transferases – Transfer functional groups

Hydrolases – Hydrolysis reactions

Lyases – Add/remove groups without water

Isomerases – Rearrangement reactions

Ligases – Joining molecules using ATP

Mnemonic -OTHLIL

Mechanism of Action

1)Lock and Key Model

2)Induced Fit Model

(Substrate binds to active site → product formed)

Factors Affecting Enzyme Activity

1)Temperature- optimum temprature enzyme activity is high 

At low temperature enzyme activity is stop 

At high temperature enzyme activity denaturation 

2) ph-optimum ph it will be high enzyme activity 

3)Substrate concentration-Vmax is low high is the velocity of an enzyme and vise Versa 

4)Enzyme concentration-high concentration of enzyme High its velocity 

Enzyme Inhibition

1)Competitive – Competes with substrate

2)Non-competitive – Binds elsewhere

3)Irreversible – Permanently inactivates enzyme

Isoenzymes 

Definition:

Isoenzymes are different molecular forms of the same enzyme that catalyze the same biochemical reaction but differ in physical, chemical, kinetic properties and tissue distribution.

Characteristics

1)Same substrate specificity

2)Different amino acid composition

3)Different electrophoretic mobility

4)Different optimum pH & Km

5)Tissue specific distribution

Example

1)Lactate Dehydrogenase (LDH)

Tetrameric enzyme made of H & M subunits

5 isoenzymes:

LDH₁ (H₄) – Heart

LDH₂ (H₃M₁) – RBC

LDH₃ (H₂M₂) – Lung

LDH₄ (H₁M₃) – Kidney

LDH₅ (M₄) – Liver & Skeletal muscle

2)Creatine Kinase (CK) – Applications

Creatine kinase catalyzes the reversible transfer of phosphate between creatine and ATP. It exists as isoenzymes, useful in clinical diagnosis.

CK Isoenzymes

CK-BB (CK₁) – Brain, smooth muscle

CK-MB (CK₂) – Cardiac muscle

CK-MM (CK₃) – Skeletal muscle

Clinical Importance

Diagnostic markers (AST, ALT, ALP)

Used in therapy & biotechnology

Metabolic disease detection