Post on 13-Jan-2016
description
Agricultural ProductStarchLipid
Organic waste
Carbohydrate producing plant• Corn• Rice• Sago
• Tuber crop
Annual lipid producing plant
1. Peanut Arachis hypogea
2. Winged bean Psophocorpus tetragonolobus3. Soybean Glycine max
4. Corn Zea mays
5. Rice Oryza sativa
6. Sesame Sesamum indicum
7. Sunflower Helianthus annuus
Perrenial lipid producing plant
1. Castor Ricinus communis
2. Jatropa Jatropa curcas
3. Kapok Ceiba petandra
4. Rubber Hevea brasiliensis
5. Coconut Cocos nucifera
6. Moringa Moringa oleifera
7. Nutsege Aleurites mollucana
8. Kusambi Sleichera trijuga
9. Oil palm Elais guineensis
10. Avocado Persea gratissima
11. Cacao Theobroma cacao
12. Kepoh Sterculia foetida
13. Nyamplung Callophylum inophylum
14. Randu Bombax malabaricum
15. Tengkawang Shorea stenoptera
CarbohydrateA group of organic compounds that includes sugars and related
compounds
Sugar
1. Compounds with between 3 – 7 carbon atoms having many hydroxyl (alcohol) groups and either a ketone group or an aldehyde group
2. A convenient source of energy
3. Raw material for many chemical syntheses
4. Water soluble
Sugar
Triose GlyceraldehydeDihydroxyacetone
Tetroses ErythroseThreose
Pentose ArabinoseRiboseXylose
Hexose GlucoseFructoseGalactoseMannose
DisaccharidesTwo molecules of a simple sugar linked together
Sucrose
Lactose
Cellobiose
Maltose
PolysaccharidesLong chain of simple sugar
Two main functions:
1. Storage
2. Structure
Storage carbohydrateA way of storing nutrients for future needs
To cover periods when its ability to supply nutrients from photosynthesis is inadequate (during growth and regeneration)
The commonest are starches and starch like materials
It is stored at seeds or tuber
StarchA mixture of two different types of molecules:
1. amylose (a long chain of glucose joint by α-1,4 linkages)
2. amylopectin (a mixture of α-1,4 links with occasionally α-1,6 branches
In general, amylopection accounts for about 70% of starch
Starch from different source vary in ratio of amylose and amylopectin
Plants use glyoxylate cycle to convert lipids to carbohydrates
Plants use glyoxylate cycle to convert lipids to carbohydrates
GlcoGlco
Glco
Glco
Glco
Starch synthase
Xa
Xb
PP
PPGlco
Glco
Glco
GlcoGlco
PPGlco
Glco
Glco
PPGlco
GlcoGlco
Glco
Glco
Glco
PPGlco
PPGlco
Glco
Glco
Glco
Glco
Glco
Starch biosynthesis is growing from reducing end
Sucrose biosynthesis
• Sucrose is synthesized in cytosol by sucrose 6-phosphate synthase and sucrose 6-
phosphate phosphatase.
Sucrose 6-phosphate synthase is also regulated
Sucrose 6-phosphate synthase is regulate by
phosphorylation/dephosphorylation.Sucrose 6-
phosphate synthase
P
SPS kinase
SPS PPase
G 6-P Pi
Starch biosynthesis is regulated by ADP-glucose pyrophosphorylase
Lipid
Any of a group of organic compounds consisting of the fats and other substances of similar properties,
insoluble in water but soluble in fats solvent and alcoholStructurally diverse range of compounds which have 2
features in common: (1). Their presence in living organism and (2). Their general solubility in organic
solvent and insolubility in water It is characterized by the presence of fatty acid moieties
and which are best described as acyl lipids
Plant lipid
Most plants do not store large quantities of lipids, with the exception of some oilseeds
Most lipid in plants have structural role as component of membranes and are synthesized in each cells
Plant do not transport fatty and complex lipids between their tissue
The most important plant tissues involved in lipid biosynthesis are the seeds
Seeds produce large quantities of triacylglicerols Large agricultural and food industry has developed around the
extraction and utilization of lipids from oil seeds
Acyl LipidNeutral
More readily soluble in non polar hydrocarbon solvents such as light petroleum and benzene
Glycerides (triacylglycerols): trihydroxy alcohol glycerolsWaxes (fatty acid esters of long chain monohydroxy alcohols)
PolarMuch more soluble in polar solvents like ethanol
Phospholipids (diester of orthophosphoric acids)Glycolipids (one or more monosaccharide residues)
Acyl Lipid StructureMajor fatty acids
All saturated and unsaturated monocarboxylic acids with an unbranched, even numbered carbon chain
Palmitic, oleic and linoleic acids often predominateIn general, saturated acids are less abundant than unsaturated acid
Minor fatty acidsTwo main categories: (1). Saturated and the cis-mono unsaturated acids,
(2)polyunsaturated acids
Unusual fatty acidsFatty acids which have (1) non-conjugated double bonds which are trans or in an
unusual position, (2). Conjugated double bond systems, (3). Allenic double bonds, (4). triple bonds, (5). Oxygen functions and (6). Branched chain
The Major Plant Fatty Acids
Common name Symbol Structure
Lauric acid 12:0 CH3-(CH2)10-COOH
Myristic acid 14:0 CH3-(CH2)12-COOH
Palmitic acid 16:0 CH3-(CH2)14-COOH
Stearic acid 18:0 CH3-(CH2)16-COOH
Oleic acid 18:1 (9c) CH3-(CH2)7-CH=CH-(CH2)7-COOH
Linoleic acid 18:2(9c,12c)
CH3-(CH2)4-(CH2-CH=CH)2-(CH2)6-COOH
α-linoleic acid 18:3(9c,12c,15c)
CH3-(CH2)-(CH2-CH=CH)3-(CH2)7-COOH
Glycerides Fatty acid esters of trihydroxy alcohol
The fast majorities in nature have all 3 of glycerol hydroxy groups esterified with fatty acids and are called triglycerides
(triacylglycerols) They are the main constituents of natural fats and oil Food reserves in seeds and/or fleshy part of fruit
Serve as carbon store in seeds required for biosynthesis processes during seed germination not as an energy store
Triacylglycerols have an advantage over carbohydrate as storage compounds due to their weight/carbon content ratio is much
lower
Glycerides Carbon in the seed as fat requires less than half the weight as
when stored as starch Low weight is advantageous for seed dispersal
They are deposited in oil bodies which consist of oil droplet which are surrounded by a lipid monolayer
Synthesis of glycerides occur in ER membrane Apart from their obvious value to the plants, they are of
enormous commercial importance
Phospholipid Glycerophospholipids Sphingophospholipids
Glycolipid Galactosyldiglycerides
Cerebrosides sulpholipids
LIPID BIOSYNTHESIS
• Fatty acid biosynthesis-basic fundamentals• Fatty acid biosynthesis-elongation and
desaturation• Triacylglycerols
Fatty Acid Biosynthesis
CytosolRequires NADPHAcyl carrier protein
D-isomerCO2 activation
Keto saturated
MitochondriaNADH, FADH2
CoA L-isomerNo CO2
Saturated keto
Beta OxidationSynthesis
Rule
Fatty acid biosynthesis is a stepwise assemblyof acetyl-CoA units (mostly as malonyl-CoA)
ending with palmitate (C16 saturated)
Fatty acid biosynthesis is a stepwise assemblyof acetyl-CoA units (mostly as malonyl-CoA)
ending with palmitate (C16 saturated)
Activation
Elongation
Termination
3 Phases
CH3C~SCoA
O
ACTIVATION
-OOC-CH2C~SCoA
O
HCO3-
active carbon
Acetyl-CoA carboxylase
ATP
ADP + Pi
1. Acetate is the basic two-carbon unit from which fatty acids are synthesis
2. It must be first converted to acetyl-CoA
3. Acetyl-CoA is produced in large quantities from pyruvate in mitochondria of photosynthetic tissue or from glucose via the glycolitic pathway in non-photosynthetic tissue
4. In addition to acetyl CoA, malonyl CoA is an essential substrate for fatty acid synthesis and is produced by the carboxylation of acetyl CoA, catalyzed by Acetyl-CoA carboxylase
Acetyl-CoA Carboxylase
The rate-controlling enzyme of FA synthesis • In Eukaryotes - 1 protein
(1) Single protein, 2 identical polypeptide chains
(2) Each chain Mwt = 230,000 (230 kDa) (3) Dimer inactive
(4) Activated by citrate which forms filamentous form of protein that can be seen in the electron microscope
Acetyl-CoA Carboxylasein Plants
1. It is located in the chloroplasts in leaf tissue and in plastids in seeds
2. Unlike the enzyme in animal tissue, this is not activated by citrate, instead small changes in stromal pH or Mg or K concentration can
markedly affect enzyme activity
3. The enzyme is also regulated by a heat stable factor found in leaves and is influenced by the ratio of ADP to ATP
4. High ATP levels activate the enzyme
Overall Reaction
CH3C~SCoA
O
CH3C-
O
CH2C~S-
O
ACP
HS-CoACO2
NOTE
Malonyl-CoA carbons become new COOH end
Acyl CarrierProtein
Malonyl-CoA + ACP
-OOC-CH2C~S-
O
ACP + HS-CoA
Initiation
Synthesis of long chain saturated fatty acids from acetyl-CoA and
malonyl-CoA
1. It take place on a complex enzyme called fatty acid synthetase
2. FA synthetase 3 groups:
a. Type I synthetase found in animals, yeast and some bacteria
b. Type II synthetases occur in most bacteria and plant tissue
c. Type III synthetase involved in the elongation of existing fatty acid
CH3C-
O
CH2C~S-
O
ACP
NADPH
CH3CH2CH2C~S-
O
ACP
CH3C- CH2C~S-
O
ACP
HO
H
CH3C- = C- C~S-
O
ACPH
H
-H2O
NADPH
-Carbon Elongation
D isomer
Reduction
Dehydration
Reduction
-Ketoacyl-ACP reductase
-Hydroxyacyl-ACP dehydrase
Enoyl-ACP reductase
-KS
CO2
-S-ACP
TERMINATION Ketoacyl ACPSynthase
Free to bindMalonyl-CoA
Transfer to KS
Split out CO2
Transfer to Malonyl-CoA
-CH2CH2CH2C~S-
O
ACP
When C16 stage is reached, instead of transferring to KS,the transfer is to H2O and the fatty acid is released
ACP
KS -SH
HSAcetyl-CoA
CoA-SH
-C-CH3
OS
KS S-C-CH3
OKS -SH
SH
CoA-SH
Malonyl-CoA
S -C-CH2-COO-
O
CO2C=O
CH2
C=O
CH3
S
O
CH3-CH -CH2-C-S
OH
OCH3-CH=CH-C-S
OCH3-CH2-CH2-C-S
S-C-CH2-CH2-CH3
O
KS
KS
NADP+
NADPH H+
NADPH H+
NADP+
H2O
Initiation or priming
Elongation
Fatty Acid SynthaseFatty Acid Synthase
-Ketoacyl-ACP reductase
-Ketoacyl-ACP reductase
-Hydroxyacyl-ACP dehydrase
-Hydroxyacyl-ACP dehydrase
Enoyl-ACP reductase
Enoyl-ACP reductase
-Keto-ACP synthase (condensing enzyme)
-Keto-ACP synthase (condensing enzyme)
Malonyl-CoA-ACP transacylase
Malonyl-CoA-ACP transacylase
Acetyl-CoA-ACP transacylase
Acetyl-CoA-ACP transacylase
-Ketoacyl-ACP synthase
-Ketoacyl-ACP synthase
TE
TE
Substrate Entry Reduction Thioesterasepalmitate release
Substrate EntryReductionThioesterasepalmitate release
ACP
ACP
HSSH
AT
AT
CH2
CH2
HSSH
CE
CE
MT
MTER
ERKR
KR DH
DH
Translocation
Translocation
Overall Reactions
Acetyl-CoA + 7 malonyl-CoA + 14NADPH + 14H+
Palmitate + 7CO2 + 14NADP+ + 8 HSCoA + 6H2O
7 Acetyl-CoA + 7CO2 + 7ATP 7 malonyl-CoA +7ADP + 7Pi + 7H+
8 Acetyl-CoA + 14NADPH + 7H+ + 7ATP Palmitate + 14NADP+ + 8 HSCoA + 6H2O + 7ADP +
7Pi
7H+
PROBLEM:
Fatty acid biosynthesis takes place in thecytosol. Acetyl-CoA is mainly in the
Mitochondria
How is acetyl-CoA made available to the cytosolicfatty acyl synthase?
SOLUTION:
Acetyl-CoA is delivered to cytosol from the mitochondria as CITRATE
acetyl-CoA
COO
COO
HO-C-COO
CH2
CH2
COO
COO
HO-C-COO
CH2
CH2
Citrate lyase
Acetyl-CoA
COO
COOCH2
C=O
COO
COOCH2
HO-C-H
NADH
OAA
L-malate
C=OCOO
CH3
NADP+
NADPH + H+
L-malate
mitochondria
CytosolPyruvate
Malic enzymeOAA
Acetyl-CoACO2
PyrCO2
Malatedehydrogenase
HS-CoA
Post-Synthesis Modifications
C16 satd fatty acid (Palmitate) is the productElongation
UnsaturationIncorporation into triacylglycerols
Incorporation into acylglycerol phosphates
C16 satd fatty acid (Palmitate) is the productElongation
UnsaturationIncorporation into triacylglycerols
Incorporation into acylglycerol phosphates
Elongation of Chain (two systems)
HS-CoA
R-CH2CH2CH2C~SCoAO
OOC-CH2C~SCoA
OCO2
Malonyl-CoA* (cytosol)
R-CH2CH2CH2CCH2C~SCoAO O
O R-CH2CH2CH2CH2CH2C~SCoA
NADPH NADH
1
- H2O2
NADPH3
Elongation systems arefound in smooth ER andmitochondria
CH3C~SCoA
OAcetyl-CoA(mitochondria)
DesaturationRules:
The fatty acid desaturation system is in the smooth membranes of the endoplasmic
reticulum
There are 4 fatty acyl desaturase enzymes in mammals designated 9 , 6, 5, and 4 fatty
acyl-CoA desaturase
Mammals cannot incorporate a double bondbeyond 9; plants can.
Mammals can synthesize long chain unsaturated fatty acids using desaturation and elongation
The Desaturase System requires O2 andresembles an electron transport system
Rule:
NADHCyt b5 reductase
Cyt b5O2
Saturated FA-CoA
(FAD)
NOTE:
1. System is in ER membrane
2. Both NADH and the fatty acid contribute electrons
3. Fatty acyl desaturase is considered a mixed function oxidase
2
2
3
1
Desaturase
Cyt b5
reductase
Cyt b5
C18-stearoly-CoA + O2 + 2H+
C18 9-oleyl-CoA + 2H2O
2 cyt b5 Fe2+ 2 cyt b5 Fe2+
2H+ + cyt b5 reductaseFAD
cyt b5 reductase FADH2
NADH + H+NAD+
Fatty acid desaturation systemFatty acid desaturation system
Desaturase
Palmitate
Stearate
Oleate
Linoleate
-Linolenate-Linolenate
Eicosatrienoate
Arachidonate
18:3(9,12,15)
18:2(9,12)
18:3(6,9,12)
16:0
18:0
Elongase
18:1(9)
Palmitoleate
16:1(9)Desaturase
Desaturase
Desaturase
Desaturase
Desaturase
Desaturase
Elongase
20:3(8,11,14)
20:4(5,8,11,14)
Other lipids
Permittedtransitionsin mammalsEssential
fatty acid
Plant Cell Wall They are not chemically homogeneous but composed of several
different materials They are not physically homogeneous but built up of distinct layers
The most important (90%) component of all plant cell walls of dicotyledonous are polysaccharides and about 10% is lignin,
protein, water and incrusting substance In monocot, the primary wall (the wall initially formed after the
growth of cell consists of 20-30% cellulose, 25% hemicellulose, 30% pectin, and 5-10% glycoprotein; when the cells reach its final size , the secondary wall consists mainly of cellulose, is added to
the primary wall Lignin which is a complex, highly ramified polymer of
phenylpropane residues
Polysaccharides
Micro-fibril polysaccharides1. Cellulose (plant cell wall)
2. Chitin (fungi cell wall)3. Β-1,4-mannans (green algae cell wall)
4. Β-1,3-xylans (green algae cell wall)
Matrix polysaccharides1. Hemicellulose
2. Pectins
Cellulose
The most abundant organic substance on earth, representing about half of the total organically bound carbon
An unbranched polymer consisting of D-glucose molecules which are connected to each other by glycosidic (β1→4) linkage
Each glucose unit is rotated by 180° from its neighbor, so that very long, straight chains can be formed with a chain length of
2000-8000 glucose residues About 150 cellulose chains are associated by inter-chain
hydrogen bonds to a crystalline lattice structure known as a microfibril
Plant cell wall micro-fibril
Cellulose micro-fibrils consisted of about 36 chains of cellulose, a polymer of b(14)glucose
These crystalline regions are impermeable to water
Micro-fibrils have unusual highly tensile strength, very resistant to chemical and biological degradation. They are very difficult to hydrolise
Plant cell wall micro-fibril
Many bacteria and fungi have cellulose-hydrolysing enzymes (cellulase)
These bacteria can be found in the digestive track of some animals enabling them to digest grass and straw
Hemicellulose
A group of polysassharide which were relatively easily extracted from various plant tissues
It can be extracted by alkaline solutionThe name is in corrected, it thought to be a precursor of
cellulose (half built cellulose) it consists of a variety of un-branched polysaccharides
which contain D-glucose, hexose and pentose3 subgroups: xylans, mannans and galactans
Pectin
A mixture of polymers from sugar acids such as D-galacturonic acids, which are connected by (α-
1→4) glycosidic linksSome of the carboxyl groups are esterified by
methyl groupsThe free carboxyl groups of adjacent chains are
linked by Ca and Mg
Lignin
An important constituent of the cell wall of xylemLignification of the cell wall occurs after the lying down
of the polysaccharides component of the walls and towards the end of growing period of the cells
The distribution of lignin in the wall is not uniformLignin strengthen the wall by forming a ramified network
throughout the matrix, thus anchoring the cellulose micro-fibril more firmly and protect the micro-fibrils of
the wall from chemical, physical and biological attack
Cellulose biosynthesis
1. It is formed at the outer surface of the plasmalemma
2. Cellulose is synthesized by terminal complexes or rosettes, consisting of cellulose synthase and associated enzymes.
Terminal complex (rosette)
Cellulose synthase
Cellulose synthase has not been isolated in its active form, but from the hydropathy plots
deduced from its amino acid sequence it was predicted to have eight trans-membrane
segments, connected by short loops on the outside, and several longer loops exposed to the
cytosol.
Initiation of new cellulose chain
synthesis
Glucose is transferred from UDP-glucose to a
membrane lipid (probably sitosterol) on the inner
face of the plasma membrane.
New cellulose chain synthesis (1)
Intracellular cellulose synthase adds several more glucose residues to the first one, in (b14) linkage, forming a short oligosacchairde chain attached to
the sitosterol (sitosterol dextrin).
New cellulose chain synthesis
Next, the whole sitosterol dextrin flips across to the outer face of the plasma membrane, where
most of the polysaccharide chain is removed by endo-1,4-
β-glucanase.
New cellulose chain synthesis
The dextrin primer (removed from
sitosterol by endo-1,4-β-glucanase) is now
(covalently) attached to another form of
cellulose synthase.
New cellulose chain synthesis
The UDP-glucose used for cellulose synthesis is
generated from sucrose produced from
photosynthesis, by the reaction catalyzed by
sucrose synthase (this enzyme is wrongly
named).
New cellulose chain synthesis (5)
• The glucose associated with UDP is a-linked.
• Its configuration will be converted by glycosyltransferases so the product (cellulose) is β-linked.
Matrix polysaccharides• They are synthesized in the cisternae of the golgi
bodies• Synthase enzymes catalyze the formation of pectin
and hemicellulose