Sintesis Asam Lemak (2)

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<p>Sintesis Asam Lemak</p> <p>Sintesis Asam LemakOleh kelompok 4Mochammad Febry PratamaNinda Ramadani Herli NSifa Fauziah Dwidaraterjadi di sitoplasma khususnya pada bagian hepar dan kelenjar adiposaSintesis asam lemak terjadi apabila kelebihan Asetil-KoA.Reaksi dimulai dgn membawa asetil KoA keluar dari mitokondria ke sitoplasma melalui torak sitrat (citrate shuttle).</p> <p>torak sitrat (citrate shuttle).</p> <p>Source:http://themedicalbiochemistrypage.org/lipid-synthesis.php3</p> <p>Citrate Shuttle (regeneration of pyruvate)</p> <p> Oxaloacetate is converted back to pyruvate for re-entry into mitochondriaStep 1. Oxaloacetate + NADH + H+ malate + NAD+. Reverse of the TA cycle reaction. Catalyzed by cytosolic malate dehydrogenase.Step 2. Malate + NADP+ pyruvate + CO2 + NADPH. Catalyzed by malic enzymePyruvate translocase transports pyruvate into mitochondria.Pyruvate is converted to oxaloacetate by pyruvate carboxylase with coupled hydrolysis of one ATP. Pyruvate + ATP + CO2 + H2Ooxaloacetate + ADP + Pi (reaction of gluconeogenesis)Net Reaction: NADP+ + NADH + H+ + ATP + H2O NADPH + NAD+ + ADP + PiThus, transport of acetylCoA to cytosol requires expense of one ATP and conversion of one NADH to NADPH.Reaksi ini terjadi dalam 4 tahap dengan pemanjangan 2 atom karbon, yaitu: Condensation Reduction Dehydration reduction</p> <p>Reaksi ini membutuhkan:NADPH (Reaksi Enzim Malat; HMP Shunt;Reaksi TCA) digunakan untuk sintesis sebagai reduktorATP untuk membentuk ikatan tioester pada asetil KoA dan menggabungkan CO2 pada asetil KoA menjadi malonil KoACO2</p> <p>Pembentukan Malonyl-CoAReaksi ini katalisis oleh enzim Acetyl CoA Carboxylase (mengandung gugus prostetik biotin)yang diaktifkan oleh sitrat dan Insulin</p> <p>Pemanjangan rantai</p> <p>Sumber:harper10</p> <p>Source:http://www.csun.edu/~jm77307/Fatty%20Acid%20Biosynthesis.pdf</p> <p>11</p> <p>Elongation of Palmitate to Stearoyl</p> <p>Sintesis asam lemak tak jenuhThe double bonds of palmitoleate and oleate are introduced in vertebrates by fatty acyl-CoA desaturase, together with cytochrome b5 and cytochrome b5 reductase;</p> <p>Two substrates, fatty acyl-CoA and NADPH, are oxidized simultaneously by O2 . The desaturase is thus a mixed-function oxidase.Desaturation of fatty acids:</p> <p>Fatty acyl-CoA is desaturated (oxidized) using O2 and NADPH(in smooth ER)ER membrane</p> <p>DIAGRAM OF SYNTHESIS</p> <p>Asam lemak essensialAsam Lemak essensialAsam lemak essensial tidak dapat dihasilkan sendiri oleh tubuh karena tidak mempunyai enzim yang dapat menyisipkan ikatan ganda diluar posisi 9 di asam lemak jenuh.</p> <p>Asam lemak yang essensial bagi mamalia adalah asam lemak linoleat dan -linolenat.</p> <p>Sintesis asam lemak esensial22</p> <p>Sintesis omega 3Fatty acid elongation and desaturase(s) systems act jointly in generation of long- and very-long-chain unsaturared fatty acids. Starting from C16 and C18, elongation specific desaturases. generate cis-monounsaturated palmitoleic acid (9,C16:1) and oleic acid (9,C18:1; Fig.1). Both palmitoleic and oleic acid are then used for the synthesis of avariety of other long-chain unsaturated fatty acidsAnimasihttp://www.wiley.com/college/fob/quiz/quiz19/19-22.htmlhttp://www.wiley.com/college/pratt/0471393878/student/animations/fatty_acid/index.htmlhttp://bio-animations.blogspot.com/2008/04/biochemistry-fatty-acid-metabolism.html</p>