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Carbohydrates

Carbohydrates. By Nurkhasanah , Ph.D. General characteristics. the term carbohydrate is derived from the french: hydrate de carbone compounds composed of C, H, and O (CH 2 O) n when n = 5 then C 5 H 10 O 5 not all carbohydrates have this empirical formula: deoxysugars, aminosugars

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Carbohydrates

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  1. Carbohydrates By Nurkhasanah, Ph.D.

  2. General characteristics • the term carbohydrate is derived from the french: hydrate de carbone • compounds composed of C, H, and O • (CH2O)n when n = 5 then C5H10O5 • not all carbohydrates have this empirical formula: deoxysugars, aminosugars • carbohydrates are the most abundant compounds found in nature (cellulose: 100 billion tons annually)

  3. General characteristics • Most carbohydrates are found naturally in bound form rather than as simple sugars • Polysaccharides (starch, cellulose, inulin, gums) • Glycoproteins and proteoglycans (hormones, blood group substances, antibodies) • Glycolipids (cerebrosides, gangliosides) • Glycosides • Mucopolysaccharides (hyaluronic acid) • Nucleic acids

  4. Functions • sources of energy • intermediates in the biosynthesis of other basic biochemical entities (fats and proteins) • associated with other entities such as glycosides, vitamins and antibiotics) • form structural tissues in plants and in microorganisms (cellulose, lignin, murein) • participate in biological transport, cell-cell recognition, activation of growth factors, modulation of the immune system

  5. Classification of carbohydrates • Monosaccharides (monoses or glycoses) • Trioses, tetroses, pentoses, hexoses • Oligosaccharides • Di, tri, tetra, penta, up to 9 or 10 • Most important are the disaccharides • Polysaccharides or glycans • Homopolysaccharides • Heteropolysaccharides • Complex carbohydrates

  6. Monosaccharides • also known as simple sugars • classified by 1. the number of carbons and 2. whether aldoses or ketoses • most (99%) are straight chain compounds • D-glyceraldehyde is the simplest of the aldoses (aldotriose) • all other sugars have the ending ose (glucose, galactose, ribose, lactose, etc…)

  7. Aldose sugars

  8. Ketose sugars

  9. Carbohydrate configuration Sistem D,L-monosakarida Atom C kiral adalah atom karbon yang keempat tangannya mengikat gugus yang berbeda-beda. Dalam sistem D dan L, suatu monosakarida merupakan anggota deret D jika gugus hidroksi pada karbon kiral terjauh dari karbon 1 terletak di sebelah kanan dalam proyeksi Fischer. Jika OH pada karbon kiral terakhir diproyeksikan ke kiri, maka senyawa itu merupakan anggota deret-L. Gliseraldehide mempunyai 1 atom C kiral, mempunyai 2 enantiomer (bentuk bayangan cermin),

  10. Aldotetrosa mempunyai 4 atom C dengan 2 atom C kiral, sehingga aldotetrosa mempunyai 22=4 stereoisomer, 2 pasang D & L enantiomer, yang disebut: eritrosa (D,L), threosa (D,L). Aldopentosa mempunyai 3 atom C kiral, berarti mempunyai 23=8 stereoisomer. Ribosa, arabinosa, ksilosa, liksosa mempunyai 4 pasang D & L enantiomer. Aldoheksosa (allosa, altrosa, glukosa, mannosa, gulosa, idosa, galaktosa, talosa) mempunyai 4 atom C kiral, sehingga mempunyai 24=16 stereoisomer, yaitu 8 pasang D & L enantiomer. Jumlah stereoisomer yang dimiliki oleh monosakarida adalah 2n, dimana n adalah jumlah atom karbon kiral. Dari keseluruhan stereoisomer tersebut, separuhnya adalah deret D dan separuh yang lain termasuk deret-L. Gambar di bawah menunjukkan proyeksi Fischer dari semua D-aldosa dari D-gliseraldehid sampai D-aldoheksosa

  11. Configurasi: sistem (R) dan (S) • R = rectus= kanan, S=sisnister=kiri • Dalamsistem (R) dan (S), gugus-gugusdiberiurutanprioritas: • 1. Urutkankeempatgugusmenurutprioritasnya • 2. Proyeksikanmolekulshf yang berprioritasterendahberarahkebelakang • 3. Pilihgugusdenganprioritastertinggidangerakkankegugusprioritasberikutnya. • 4. Jikagerakansearahjarum jam makakonfigurasi (R), jikaberlawanankonfigurasi (S)

  12. Structural representation of sugars • Fisher projection: straight chain representation • Haworth projection: simple ring in perspective • Conformational representation: chair and boat configurations

  13. suatu rumus Haworth digambar dengan oksigen cincin berada pada sisi terjauh dari cincin dan karbon 1 berada di sebelah kanan. Gugus CH2OH ujung ditempatkan di atas bidang cincin untuk deret D, dan di bawah bidang cincin untuk deret-L. Atom-atom hidrogen, pada karbon cincin biasanya tidak ditampakkan dalam proyeksi Haworth.

  14. Penulisan monosakarida dari proyeksi Fischer ke proyeksi Haworth • gugus yang terletak di sebelah kanan proyeksi Fischer berada di sebelah bawah proyeksi Haworth, selanjutnya gugusan yang berada di sebelah kiri beRada di sebelah atas dalam rumus Haworth.

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