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Agricultural Product Starch Lipid Organic waste Carbohydrate producing plant • Corn • Rice • Sago • Tuber crop Annual lipid producing plant 1. Peanut Arachis hypogea 2. 3. Winged bean Soybean Psophocorpus tetragonolobus 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 Carbohydrate A 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 Glyceraldehyde Dihydroxyacetone Tetroses Erythrose Threose Arabinose Ribose Xylose Glucose Fructose Galactose Mannose Pentose Hexose Disaccharides Two molecules of a simple sugar linked together Sucrose Lactose Cellobiose Maltose Polysaccharides Long chain of simple sugar Two main functions: 1. Storage 2. Structure Storage carbohydrate A 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 Starch A 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 Starch biosynthesis is growing from reducing end o Glc P P Starch synthase Xa Xb o Glc o Glc o o Glc o Glc o Glc o Glc Glc P P o Glc o Glc o Glc Sucrose biosynthesis • Sucrose is synthesized in cytosol by sucrose 6-phosphate synthase and sucrose 6phosphate phosphatase. Sucrose 6-phosphate synthase is also regulated G 6-P Pi P Sucrose 6phosphate synthase SPS kinase SPS PPase Sucrose 6-phosphate synthase is regulate by phosphorylation/dephospho rylation. 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 alcohol Structurally 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 Lipid Neutral More readily soluble in non polar hydrocarbon solvents such as light petroleum and benzene Glycerides (triacylglycerols): trihydroxy alcohol glycerols Waxes (fatty acid esters of long chain monohydroxy alcohols) Polar Much more soluble in polar solvents like ethanol Phospholipids (diester of orthophosphoric acids) Glycolipids (one or more monosaccharide residues) Acyl Lipid Structure Major fatty acids All saturated and unsaturated monocarboxylic acids with an unbranched, even numbered carbon chain Palmitic, oleic and linoleic acids often predominate In general, saturated acids are less abundant than unsaturated acid Minor fatty acids Two main categories: (1). Saturated and the cis-mono unsaturated acids, (2)polyunsaturated acids Unusual fatty acids Fatty 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,1 CH3-(CH2)4-(CH2-CH=CH)22c) (CH2)6-COOH α-linoleic acid 18:3(9c,1 CH3-(CH2)-(CH2-CH=CH)3-(CH2)72c,15c) 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 Synthesis Cytosol Requires NADPH Acyl carrier protein D-isomer CO2 activation Keto saturated Beta Oxidation Mitochondria NADH, FADH2 CoA L-isomer No CO2 Saturated keto Rule Fatty acid biosynthesis is a stepwise assembly of acetyl-CoA units (mostly as malonyl-CoA) ending with palmitate (C16 saturated) 3 Phases Activation Elongation Termination ACTIVATION CH3C~SCoA O HCO3- ATP ADP + Pi -OOC-CH 2C~SCoA O active carbon Acetyl-CoA carboxylase 1. Acetate is the basic two-carbon unit from which fatty acids are synthesis 2. It must be first converted to acetylCoA 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 Initiation Overall Reaction Malonyl-CoA + ACP -OOC-CH CH3C~SCoA 2C~S- O O CO2 HS-CoA CH3C-CH2C~SO ACP + HS-CoA Acyl Carrier Protein ACP O NOTE Malonyl-CoA carbons become new COOH end 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 -Carbon Elongation CH3C-CH2C~S- NADPH D isomer O Reduction O -Ketoacyl-ACP reductase H CH3C-CH2C~SHO O -H2O NADPH ACP ACP Dehydration -Hydroxyacyl-ACP dehydrase H CH3C-= C- C~S- ACP H O Enoyl-ACP reductase CH3CH2CH2C~S- ACP O Reduction TERMINATION -KS Transfer to Malonyl-CoA Ketoacyl ACP Synthase Transfer to KS -S-ACP -CH2CH2CH2C~S- ACP Free to bind Malonyl-CoA O Split out CO2 CO2 When C16 stage is reached, instead of transferring to KS, the transfer is to H2O and the fatty acid is released Fatty Acid Synthase O S-C-CH2-CH2-CH3 -Ketoacyl -ACP synthase KS O CH3-CH2-CH2-C-S Acetyl-CoA HS CoA-SH NADP+ Enoyl-ACP reductase NADPH H+ O CH3-CH=CH-C-S -Hydroxyacyl-ACP H2O KS ACP Initiation or priming O S-C-CH3 SH Malonyl-CoA Malonyl-CoACoA-SH ACP transacylase O O S -C-CH2-COO- CH3-CH -CH2-C-S -Ketoacyl -ACP reductase O S -C-CH3 KS -SH dehydrase OH Acetyl-CoAACP transacylase KS NADP+ NADPH H+ S C=O CH2 C=O CH3 -Keto-ACP synthase (condensing enzyme) CO2 KS -SH Elongation Substrate Entry Reduction Thioesterase palmitate release AT MT DH KR ER ACP CE CH2 Translocation HS HS TE SH SH Translocation CH2 CE TE Thioesterase palmitate release ACP ER KR DH Reduction MT AT Substrate Entry Overall Reactions Acetyl-CoA + 7 malonyl-CoA + 14NADPH + 14H 7H++ 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 PROBLEM: Fatty acid biosynthesis takes place in the cytosol. Acetyl-CoA is mainly in the Mitochondria acetyl-CoA How is acetyl-CoA made available to the cytosolic fatty acyl synthase? SOLUTION: Acetyl-CoA is delivered to cytosol from the mitochondria as CITRATE CH2COO HO-C-COO mitochondria CH2COO CH2COO HO-C-COO OAA CO2 Pyr Acetyl-CoA Citrate lyase COO C=O OAA Malate CH2 dehydrogenase COO NADH CH2COO Acetyl-CoA HS-CoA L-malate CO2 COO HO-C-H L-malate CH2 COO Malic enzyme NADP+ NADPH + H+ COO C=O Pyruvate CH3 Cytosol Post-Synthesis Modifications C16 satd fatty acid (Palmitate) is the product Elongation Unsaturation Incorporation into triacylglycerols Incorporation into acylglycerol phosphates Elongation of Chain (two systems) R-CH2CH2CH2C~SCoA Malonyl-CoA* O (cytosol) HS-CoA OOC-CH2C~SCoA CH3C~SCoA CO2 O O Acetyl-CoA (mitochondria) R-CH2CH2CH2CCH2C~SCoA O O 1 NADPH Elongation systems are NADH found in smooth ER and 2 - H2O 3 NADPH mitochondria R-CH2CH2CH2CH2CH2C~SCoA O Rules: Desaturation 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 bond beyond 9; plants can. Mammals can synthesize long chain unsaturated fatty acids using desaturation and elongation Rule: The Desaturase System requires O2 and resembles an electron transport system NADH 2 Cyt b5 reductase O2 Cyt b5 3 (FAD) Saturated FA-CoA 1 2 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 Fatty acid desaturation system C18-stearoly-CoA C18 9-oleyl-CoA + O2 + 2H+ + 2H2O Desaturase Desaturase 2 cyt b5 Fe2+ 2 cyt b5 Fe2+ Cyt b5 2H+ + cyt b5 reductase FAD NADH + H+ cyt b5 reductase FADH2 NAD+ Cyt b5 reductase Desaturase Palmitoleate 16:1(9) Palmitate 16:0 Elongase Stearate 18:0 Permitted transitions in mammals Desaturase Essential fatty acid Desaturase -Linolenate 18:3(9,12,15) Other lipids Oleate 18:1(9) Desaturase Linoleate 18:2(9,12) Desaturase -Linolenate 18:3(6,9,12) Elongase Eicosatrienoate 20:3(8,11,14) Desaturase Arachidonate 20:4(5,8,11,14) 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 polysaccharides 1. 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 polysaccharides 1. 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 solution The 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 pentose 3 subgroups: xylans, mannans and galactans Pectin A mixture of polymers from sugar acids such as D-galacturonic acids, which are connected by (α1→4) glycosidic links Some of the carboxyl groups are esterified by methyl groups The free carboxyl groups of adjacent chains are linked by Ca and Mg Lignin An important constituent of the cell wall of xylem Lignification 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 uniform Lignin 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-1,4β-glucanase. New cellulose chain synthesis The dextrin primer (removed from sitosterol by endo-1,4β-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