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Lipid lectures > Glycerophospholipid synthesis > Flashcards

Glycerophospholipid synthesis Flashcards

1
Q

what is a type of storage lipid?

A

TAG’s

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2
Q

what are 2 kinds of membrane lipids

A

phospholipids

Glycolipids

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3
Q

what are the 2 groups of phospholipids?

what are their structure?

A

glycerophospholipids

  • 2 FA
  • a phosphate and a head group (ie, alcohol)

sphingolipids

  • one FA
  • a phosphate and a head group (ie. choline)
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4
Q

what is one type of glycolipids?

structure?

A

sphingolipids

  • 1 fatty acid
  • a mono or oligosaccharide
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5
Q

how is ester made

A

an ester linkage is formed
when a hydroxyl group reacts with a carboxylic acid in a condensation reaction, which
liberates a water molecule

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6
Q

what results from first addition of FA

A

phosphatidic acid AKA diacylglycerol-3-phosphate

only present in small amounts, but is key intermediate

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7
Q

what are 5 possible alcohols that can serve as a head group?

A

serine

ethanolamine

Choline

glycerol

inositol

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8
Q

palmitic acid saturation

A

fully saturated

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9
Q

oleic acid saturation

A

one double bond

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10
Q

what is the simplest glycerolphospholipid

A

phosphatidic acid

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11
Q

name the others based on the alcohol groups

which on is name a little differently

A

phosphatidylinositol 4,5 bisphosphate

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12
Q

which one has a glycerophospholipid within another?

what is its head group?

A

cardiolipin

phosphatidyl glycerol

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13
Q

what are Ether phospholipids

A

glycerophospholipids in which the fatty acid at

position C1 of glycerol is attached with an ether linkage.

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14
Q

what kind are plasmologens

where are they found?

A

vinyl ether lipids, with an unsaturated double bond between C1 and C2 of the alkene
chain. Plasmalogens are abundant in the membranes of cardiac muscle tissue,
as well as many single cell organisms.

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15
Q

what is the structure of choline

A

CH2-CH2-N+(CH3)3

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16
Q

what is the structure of plasmologens

A

ether linkage

esterlinkage

phosphate and choline

Note: saturated alkene chains

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17
Q

Platelet activating factor structure

roles?

A

is a 1-alkyl-2-acetyl ether analog of
phosphatidylcholine. It promotes the aggregation of platelets and the release of
the vasoconstrictor, serotonin, from platelets. Platelet activating factor also
plays an important role in inflammation and the allergic response in a variety of
tissues.

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18
Q

Sphingosine

A

has a long hydrocarbon tail and a polar region that includes an amino group. The
amino group can form an amide bond with the carboxylic group of fatty acids,
yielding ceramide.

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19
Q

what is the only membrane phospholipid not

derived from glycerol.

A

Sphingomyelin is the only membrane phospholipid not

derived from glycerol.

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20
Q

name the head groups of sphingolipids

A

ceramide has an H or none

phosphocholine

glucose

di,tri or tetrasaccharide

complex oligosaccharide

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21
Q

name that sphingolipids with various head groups

A

ceramide

sphingomyelin (only membrane phospholipid not
derived from glycerol.)

neutral glycolipids Glucosylcerebroside

lactosylceramide (a globoside)

ganglioside GM2

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22
Q

The eicosanoids

A

The eicosanoids paracrine hormones derived from polyunsaturated 20-carbon
fatty acids, predominantly arachadonic acid. The eicosanoids elicit a variety of
effects on numerous vertebrate tissues.

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23
Q

sialic acid?

A

makes sphingonine???

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24
Q

In general, the assembly of phospholipids from simple precursors
requires:

A

(i) synthesis of the backbone molecular, (ii) attachment of fatty acid(s) to
the backbone in ester or ether linkages, (iii) addition of a hydrophilic headgroup
joined to the backbone molecule via a phosphodiester bond, and in some cases,
(iv) alteration or exchange of the headgroup to yield the final phospholipid

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25
Q

where does phospholipid synthesis occur?

A

In bacteria, phospholipid biosynthesis occurs at the plasma membrane;
in eukaryotic cells, it occurs primarily at the surface of the smooth endoplasmic
reticulum.

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26
Q

The first steps of glycerophospholipid biosynthesis are shared with

A

the pathway for the synthesis of triacylglycerols.

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27
Q

what enzyme transfers Acyl-CO’s to glycerol 3 phoshate

A

acyl transferase

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28
Q

how is glycerol 3 phosphate made?

A

by glycerol 3 phoshate dehydrogenase and by glycerol kinase

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29
Q

how are FA activated

A

acyl-CoA synthetase

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30
Q

what is endo product after adding 2 acyl groups to glycerol

A

phosphatidic acid

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31
Q

what can phosphatidic acid become if it is dephosphorylated

A

1,2- diacylglycerol via phosphatidic acid phosphatase

what happens if another acyl group is added?

it becomes triacylglycerol

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32
Q

what can phosphatidic acid become of a head group is added

A

general name : glycerolphospholipid

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33
Q

What is partiular about the bond used to attach the Head group?

A

The polar head group of is attached through a phosphodiester bond. However, the
phosphodiester bond is not the result of direct condensation reactions between
phosphoric acid and two alcohols.

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34
Q

Biosynthetically, this occurs through activation of the one of the hydroxyls by the
nucleotide cytidine diphosphate. What are the 2 strategies used?

A

There are two strategies for the attachment of

headgroups, via: (i) activated diacylglycerol, or (ii) an activated headgroup.

35
Q

describe the strategies.

who uses it?

A

-The first strategy, activated diacylglycerol, is utilized by bacteria, and by eukaryotes
for some lipids [see below]).

-(CDP diacylglycerol is acitvating molecule.)

-Eukaryotes synthesize their anionic phospholipids (PG, CL, and PI) in a manner similar
to bacteria, through the use of activated diacylglycerol. Note that CL synthesis differs in
that prokaryotes condense two PG while eukaryotes condense activated diacylglycerol
with PG.
Yeast

-Yeast and bacteria use similar approaches to synthesize PS and PE (via serine and
activated diacylglycerol), and methylate PE to make PC.

36
Q

What is unique to mammals?

A

-In mammals,
methylation of PE to
PC only happens in
the liver.

-Except for the liver, mammals use the second strategy, one of an activated
headgroup, to synthesize PC (the most abundant glycerophospholipid in animal
tissues) and PE.

37
Q

How is PS synthesized in mammals

A

Mammals synthesize PS through a headgroup-exchange of serine and ethanolamine or
serine and choline.

38
Q

how does synthesis of plasmalogens occur?

A

The synthesis of plasmalogens and other ether-linked phospholipids occurs via
dihydroxyacetone phosphate.

39
Q

number colon and another number

A

number of carbons: number of unsaturated bonds

40
Q

How do you turn off platelet activating factor

A

cleave acetyl ester

41
Q

what is the only sphingolipid that is also a phospholipid

A

sphingomyelin

42
Q

middle group of sphingolipids

A

makes amide bond

43
Q

glycerol kinase only happens in what organs

A

kidney and liver

44
Q

bacteria use what strategy

A

Bacteria employ the strategy that uses

CDP-diacylglycerol.

45
Q

Pathway for bacterial
anionic phospholipid
biosynthesis

A

leads to phosphatidylgycerol and then to cardiolipin

46
Q

Pathway for bacterial
zwitterionic phospholipid
biosynthesis

A

phosphatidylserine and phosphatidylethanolamine

47
Q

CDP-diacylglycerol strategy is used to make what in eukaryotes

A

anionic phospholipids

PG, CL and PI

48
Q

what do fungi use CDP-diacylglycerol strategy for

A

synthesis of PS and PE, and they methylate

PE to produce PC.

49
Q

mammals use headgroup exchange to:

A
  • mammals synthesize PS via a headgroup exchange with PE (or PC),
  • not from directly from CDP-diacylglycerol,
  • methylation of PE only occurs in the liver (forms PC).
50
Q

how do mammals synthesize PS

A

Mammals synthesize PS via a headgroup

exchange with PE or PC

51
Q

how do mammals synthesize PC and PE

A

Mammals use the strategy of condensing activated headgroups and diacylglcerol for synthesizing PC and PE.

52
Q

Activated choline condenses diacylglycerol to form

A

PC.

53
Q

Activated ethanolamine condenses diacylglycerol to form

A

PE

54
Q

what are most prevalent phospholipids

A

PC and PE

55
Q

Summarize strategy

A
    • BActeria use strategy 1 for everything
  2. -Eukaryotes:
    - strategy 1 to make PG, cardiolipin, phosphatidyl inositol and such
  • PS head group exchange
  • PC and PE: Energy activate head group strategy 2

KNow head groups and

56
Q

Synthesis of plasmalogens involves:

A
  1. Displacment of the 1-acyl group by a long-chain alcohol.
  2. Reduction of the ketone.
    Acylation of the C2-OH.
    Hydrolysis of 3’-phosphate.
    Condensation with activated, CDP-ethanolamine (or CDP-choline, not shown).
    Introduction of the double bond into the alkyl chain.
    Headgroup, if modified, done like with common ester-linked glycerophospholipids.
57
Q

surfactant

A

major components:

  • Dipalmidyol PC (DPPC)- major component
  • Unsaturated PC
  • PG
  • the rest: proteins, cholesterol, FA’s, other lipids
58
Q

precursor to plasmologens

A

DHAP

59
Q

Sphingolipid biosynthesis has 4 stages:

A
  1. Synthesis of sphinganine, an 18 carbon amino alcohol.
  2. Attachment of a fatty acid via an amide bond.
  3. Desaturation of the alkane chain of acylsphinganine (results in ceramide).
  4. Headgroup attachment.
60
Q

sphingomyelin synthesis

A

1- headgroup exchange with PC

  1. Previously thought that SM was synthesized from N-acylsphingosine and CDP-choline, now known that is a minor pathway.
  2. Most prevalent acyl groups in SM are 16:0 and 18:0.
  3. Synthesis occurs in the Golgi, unlike ceramide and other phospholipids.
61
Q

Glucocerebroside are where?

what is it a precursor to?

A

Glucocerebroside

A minor lipid in non-neural tissue, however it is the precursor of globosides and gangliosides.

62
Q

What is true about both Glucocerebroside and Galactocerebroside

A

Both are linked by a b-linkage at position 1 of the hexose.

63
Q

Where are Galactocerobrosides?

what are they refered to often?

A

Galactocerebroside

A common lipid in brain, often referred to as “cerebroside”

64
Q

glycerophospholipids made where

A

in smooth ER

65
Q

all others from ceramide are made

A

in the golgi (because sugars are tranfered)

66
Q

cerobrosides have how many sugars

A

one sugar

67
Q

sulfatides

A
  • synthesized: galactocerbroside reacted with PAPS
  • 15% of brain white matter lipids.
  • PAPS serves as the source for the activated sulfate group.
  • Sulfate is transferred almost exclusively to the 3-0H of galactose.
  • Note, with the addition of the sulfate, the monosaccharide has a negative charge, so sulfatides are not neutral sphingoglycolipids.
68
Q

gangliosides have

A

sialic acid

69
Q

glangioside branch (how many)

A

more than 60 known

70
Q

where are gangliosides made?

A

-Additions carried out by a series of glycosyl transferases (in Golgi).

Extra!!
-Addition of 2nd NANA to GM3 leads to GD series. Addition of GlcNAc to lacosyl ceramide before NANA leads to GA2. Overall, more than 60 known gangliosides.

71
Q

Nomenclature

A 
M  =  1 SA
D  =  2 SA
T  =  3 SA
Q  =  4 SA
Also have other letters based on branching.

= 5 - moieties (not counting SA)

72
Q

The diversity of attached sugars of the different sphingolipids allows what?

A

The diversity of attached sugars allows the different sphingolipids to serve as molecular tags or markers.

73
Q

Glycosphingolipids have many important biological roles.

A

Two examples are:

  • They participate in the cell surface structures associated with blood types.
  • Ganglioside GM1 is the receptor for cholera toxin in the human intestine.
74
Q

Describe turnoever of sphingolipids

A

The synthesis and degradation of sphingolipids is carefully controlled. Normally, there is constant turnover of sphingolipids, which occurs in lysosomes.

75
Q

What are the main attributes of lipid storage diseases?

A

most often in glycolipid storage diseases the biosynthetic rate remains normal, but a mutation exists in a structural gene for a hydrolase. Impaired degradation of sphingolipids results in accumulation of membrane lipids, which have severe clinical manifestations.

76
Q

what order are sugars removed

A

in reverse order in which they were added

77
Q

sx’s of lipid storage diseases

A

large liver and spleen

scholiosis

opaque cloudiness

macular spots

ataxia, dystonia, hypotonia

macroglossia

78
Q

Tay Sachs

A

lack hexosaminidase (GM2 to GM3)

  • High risk in the Ashkenzi Jewish population, with a 1: 25 carrier frequency.
  • An in vitro enzymatic clinical assay for Tay-Sachs disease. (fluorescent alkaline medium)
79
Q

Generalized gangliosidosis

A

beta-gangliosidase (GM1 to GM2)

80
Q

Gaucher’s

A

glucocerebrosidase (ceramide-Glc to ceramide)

-treatment

81
Q

Niemann Pick

A

sphingomyelinase (ceramide-PC to ceramide)

82
Q

fabry’s disease

A

alpha- galactosidase A ( ceramide + Glc-gal-gal)

83
Q

sandhoffs

A

hexominidase A and B ( Globoside to ceramide + Glc-gal-gal)

Lipid lectures (2 decks)

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