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Lipid-2b Classification

Metabolism

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Classification

Fatty acids

Triacylglycerols

Phosphoglycerides

Sphingolipids Steroids

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As major components of lipid molecules (triglycerides,phospholipids, sphinomyelin)

Precursors to other molecules (prostaglandins)

Provide energy (through oxidation processes)

Industrial uses (soaps, etc)

1. Fatty acid

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1. Fatty acid

Mostly have 14-20 carbons

Even number of carbons

Two numbers m:nm = number of carbonsn = number of C=C bonds

Double bonds are mostly cis

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1 CH2 OH|

2 CH OH|

3 CH2 OH

Glycerol

2. Triglycerides

Fat storage in adipocytescauses type-2 diabetes andresistin aggravates it.

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3. Phosphoglycerides

(Glycerophospholipid or Phospholipid)

1 CH2 OH|

2 CH OH

|3 CH2 OH

Glycerol

Phospholipases

Degrade phospholipidsPresent in snake venomsCause inflammation,

fever, headache

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4. Sphingolipids

-Derivatives of Sphingosine and

Dihydrosphingosine-major components of membrane

-Functions:

-Cell-cell recognition

-Tissue immunity

-Impulse transmission

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5. Steroids

Steroids stem from a single template

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Lipid-Linked protein

Lipids and proteins covalently interact to form lipid-linked proteinsPrenylated; Fatty acetylated; Glycoinositol phospholipids

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Lipoproteins

Proteins and lipids non-covalently interact to form lipoproteins

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What is this?

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Lipid metabolism

* 1. Fatty acid degradation

-oxidationKetone body

2. Fatty acid biosynthesis

3. Triacylglycerol biosynthesis

* 4. Phospholipid degradation

5. Cholesterol biosynthesis

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1. Fatty acid degradation: -oxidation

Most fatty acids are degraded to form acetyl-CoAwithin mitochondria in a process called -oxidation

Production of ATP to provide energy (resulted

from oxidation of acetyl-CoA via citric acid cycle )Process found in all living organisms

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A Key molecule in lipid metabolism

Acyl-CoA: fatty acid + Co-A

Acetyl-CoA: acetyl form of Co-A

Acyl-CoA

Acetyl-CoA

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Acyl-CoA reacts with carnitine to form acylcarnitine which can then be transportedacross the inner membrane of mitochondria and is subsequently recovered asacyl-CoA

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The -oxidation of acyl-CoA molecules include four reactions that occur in themitochondria. Each cycle of reactions forms acetyl-CoA and acyl-CoA thats shorter bytwo carbons

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Most acetyl-CoA produced from fatty acid degradation is used in citric acid cycle togenerated energy

Excess acetyl-CoA is converted to ketone bodies (acetoacetate, b-hydroxybutyrateand acetone) in a process called ketogenesis.

Occurs in liver mitochondria

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2. Fatty acid biosynthesis

A mean by which energy is stored

Occurs within cytoplasm of most animal cells.However, liver is the major site for this process

Overall reaction (palmitic acid):

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Desaturation of fatty acids

Saturated fatty acids can bedesaturated

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Glycerol

Glucose

3. Triacylglycerol biosynthesis

Even if you do not take a lotof fatty food, triglycerides canbe synthesized from glucose

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4. Phospholipid degradation

Phospholipase A 2

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Phospholipid digestion byPhospholipase A 2 (PLA2)

Phospholipase A 2 cutsa phospholipid andreleases a fatty acid

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Phospholipase A 2 (PLA2) properties1 11 21 31 41 51 61

MiPLA1 NL LQFR K MIK CTVPG R EPLV AFT DYGCYCG KGGSGTPVDE LDRCCQTHD N CYDKA EKL PE CKGILS R PYV MiPLA2 NL YQFR K MIK CTIPG R EPLL AFT DYGCYCG KGGSGTPVDE LDRCCQTHD N CYDKA EKL PE CKGILS GPYV MiPLA3 NL LQFR K MIK CTIPG I EPLL AFS N YGCYCG KGGSGTPVDE LDRCCQTHD Y CYDKA KIH PE CKGILS GPSF MiPLA4 NL LQFR N MIK CTIPG R EPLL AFS N YGCYCG KGGSGTPVDE LDRCCQTHD N CYDKA EKL PE CKGILS GPYV

71 81 91 101 111 121 MiPLA1 NTYAYDCT KG KITCNDQ KDK CKLFICNCDR TAAMCFAKA R YI E AN NH IDP KR CK MiPLA2 NTYSYDCT DG KLTCNDQ KDK CKLFICNCDR TAAMCFAKA P YI E AN NH IDP NR CK MiPLA3 NTYAYDCT DG KLTCNDQ KDK CKLFICNCDR TAAMCFAKA P YKEEN NR IDA SN CK MiPLA4 NTYSYDCT DG KLTCNDQ N DK CKLFICNCDR TAAMCFAKA P Y N E AY NH FNR QL CK

Prothrombin time assay

Hydrolytic activity

0100200300400500600

700800900

MiPLA1 2 3 40

0.050.1

0.15

0.20.25

0.30.350.4

MiPLA1 2 3 4

Dark urine induction

0

20

40

60

80

100

120

140160

Control MiPLA1 2 3 4

Muscle necrosis assay

0200400600800

100012001400160018002000

Control MiPLA1 2 3 4

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5. Cholesterol biosynthesis

From acetyl-CoA, steroids aresynthesized

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