多糖
凡能水解成多個單糖分子或其衍生物的糖為多糖。它是由二十個至數萬個單糖分子縮合、脫水而成的大分子化合物。多糖可以由一種單糖組成，如淀粉、纖維素等稱為同聚多糖；也可以由不同單糖或其衍生物縮合而成，例如半纖維素，則被稱為雜聚多糖。
自然界中，植物、動物和微生物都含有豐富的多糖。除了以游離形式存在外，多糖也常與蛋白質結合形成復合物。植物多糖的共同特點是天然性、保健價值及獨特的水溶性膠體特性，這賦予食品較高的營養價值、穩定的組織結構以及優良的外觀和口感，并延長了其貨架期。
天然植物多糖對人體更為安全，吸收率更高。例如魔芋中的葡甘聚糖，這是一種極好的水溶性膳食纖維，具有飽腹感、降血脂、降血糖及通便等保健功能。盡管植物多糖本身不提供熱量，但它對高熱量、高脂肪和高蛋白的飲食結構有平衡營養的作用。
因此，親水性的植物多糖常被稱為植物膠，它們能夠為食品生產加工提供增稠劑、凝膠劑、成膜劑及乳化劑等多種穩定劑。有效開發和利用植物多糖將有助于提升人類的生活質量、改善健康水平，并豐富食物資源，從而創造更多的經濟價值。
淀粉是儲存在植物體內的多糖，由直鏈淀粉和支鏈淀粉兩種成分構成。在淀粉顆粒中，直鏈淀粉占比20～28%，其余為支鏈淀粉。直鏈淀粉由約250至300個D-葡萄糖分子通過α 1,4糖苷鍵連接而成，并卷曲成螺旋結構，具有一個非還原性末端和一個還原性末端，其分子量差異很大，從數千到150,000不等。直鏈淀粉遇碘呈藍色反應，這是由于螺旋內部為分子碘占據所致。
支鏈淀粉由24至30個D-葡萄糖分子通過α 1,4和α 1,6糖苷鍵連接而成，形成類似灌木叢的結構。動物消化道中的α淀粉酶（存在于唾液及胰液中）可以隨機作用于α 1,4糖苷鍵，將直鏈淀粉水解成麥芽糖和葡萄糖；植物中的β淀粉酶則在直鏈淀粉非還原性末端起作用，生成麥芽糖。支鏈淀粉同樣可被α和β淀粉酶作用，但靠近分枝點的α 1,4和α 1,6糖苷鍵不被這些酶水解，在α淀粉酶及1,6葡萄糖苷酶共同作用下，支鏈淀粉完全水解為葡萄糖和麥芽糖。
瓊脂糖是瓊脂的重要組成部分，由D-半乳糖與3,6脫水半乳糖構成的單位重復縮合而成。瓊脂糖在沸水中大量溶解，但當溫度降至40℃以下時則成不溶性凝膠。這種瓊脂糖凝膠常用作層析的支持體，通過氫鍵將半乳多糖鏈交聯形成，因此在過于酸堿環境中不穩定。
相關化合物
| 中文名稱 | 英文名稱 | CAS號 | 化學式 |
|---|---|---|---|
| 醋酸丙酸纖維素酯 | Cellulose, acetate propanoate | 9004-39-1 | C76H114O49 |
| 鄰氯苯亞甲基丙二腈 | citrate synthase (unknown stereospecificity) | 9027-96-7 | —— |
| 西佐喃 | Schizophyllan | 9050-67-3 | C24H42O21 |
| 葡聚糖凝膠LH-20 | methyl 1-acetyl-1H-thieno[3,2-c]pyrazole-5-carboxylate | 9041-37-6 | C9H8N2O3S |
| 葡聚糖凝膠G-100 | Sephadex G-100 | 9050-94-6 | C226H274N28O14S6 |
| 葡聚糖凝膠 | sephadex G 75 | 37224-29-6 | C22H23FN4OS |
| 葡聚糖凝膠 | 6'-Iodononivamide | 859171-97-4 | C17H26INO3 |
| 菊粉 | Inulin (by Enzymatic synthesis) | 9005-80-5 | C228H382O191 |
| 肝素鋰 | Heparin lithium salt | 9045-22-1 | C14H25NO20S3 |
| 羧甲基醚纖維素鈉鹽 | Carmellose sodium | 9004-32-4 | C8H16NaO8 |
| 羧甲基纖維素 | 7H | 9000-11-7 | C8H16O8 |
| 羥丙基脫乙酰殼多糖 | Hydroxypropyl chitosan | 84069-44-3 | C51H101N3O24 |
| 糊精棕櫚酸酯 | (3R,4S,5S,6R)-2-[(2R,3S,4R,5R)-4,5-dihydroxy-2-(hydroxymethyl)-6-[(2R,3S,4R,5R,6S)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxyoxan-3-yl]oxy-6-(hydroxymethyl)oxane-3,4,5-triol;hexadecanoic acid | 83271-10-7 | C34H64O18 |
| 糊精 | Dextrin | 9004-53-9 | C18H32O16 |
| 硫酸類肝素 | azane;(3R,4R,5S,6R)-3-[(2S,3S,4R,5R)-5-[(2R,3S,4S,5R)-6-carboxylato-4-hydroxy-5-methoxy-3-sulfonatooxyoxan-2-yl]oxy-4-hydroxy-3-(sulfonatoamino)-6-(sulfonatooxymethyl)oxan-2-yl]oxy-4,5-dihydroxy-6-[(3S,4R,5S,6R)-6-methoxy-5-(sulfonatoamino)-4-sulfonatooxy-2-(sulfonatooxymethyl)oxan-3-yl]oxyoxane-2-carboxylate | 9050-30-0 | C26H39N3O39S6-8 |
| 甲基羥乙基纖維素 | ethane-1,2-diol;(2S,3R,4R,5S,6R)-2-(hydroxymethyl)-6-[(2S,3R,4S,5S,6S)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxyoxane-3,4,5-triol;(2S,3S,4R,5S,6S)-2,3,4-trimethoxy-6-(methoxymethyl)-5-[(2R,3S,4R,5S,6S)-3,4,5-trimethoxy-6-(methoxymethyl)oxan-2-yl]oxyoxane | 9032-42-2 | C34H66O24 |
| 瓊脂糖 | Agarose | 9012-36-6 | C24H38O19 |
| 瓊脂 | Agar | 9002-18-0 | C14H24O9 |
| 果膠 | β-D-galactopyranosiduronic acid | 9000-69-5 | C6H10O7 |
| 木聚糖 | (2R,3R,5S,6S)-tetrahydropyran-2,3,4,5,6-pentol | 9014-63-5 | C5H10O6 |
| 支鏈淀粉 | 6<sup>2</sup>-α-maltosyl-maltotriose (α-re) | 9037-22-3 | C30H52O26 |
| 小菌核(SCLEROTIUMROLFSSII)膠 | Scleroglucan | 39464-87-4 | C24H44O20P2 |
| 殼聚糖 | Chitosan | 9012-76-4 | C56H103N9O39 |
| 半乳甘露聚糖 | 6-O-α-D-galactopyranosyl-4-O-β-D-mannopyranosyl-D-mannopyranose | 11078-30-1 | C18H32O16 |
| 全氨基倍他環糊精 | heptakis(6-amino-6-deoxy)-β-cyclodextrin | 30754-24-6 | C42H77N7O28 |
| 乳糖-N-四糖 | lacto-N-tetraose | 14116-68-8 | C26H45NO21 |
| 乙基纖維 | Ethyl cellulose | 9004-57-3 | C20H38O11 |
| 三乙酸纖維素 | O-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl)-(1->4)-O-(2,3,6-tri-O-acetyl-β-D-glucopyranosyl)-(1->4)-1,2,3,6-tetra-O-acetyl-β-D-glucopyranose | 9012-09-3 | C40H54O27 |
| β-環糊精 | β-cyclodextrin | 7585-39-9 | C42H70O35 |
| Α-葡萄糖基橘皮苷 | 7-[3,4-Dihydroxy-5-[3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy-6-[(3,4,5-trihydroxy-6-methyloxan-2-yl)oxymethyl]oxan-2-yl]oxy-5-hydroxy-2-(3-hydroxy-4-methoxyphenyl)-2,3-dihydrochromen-4-one | 161713-86-6 | C34H44O20 |
| O-[2-乙酰氨基-2-脫氧-3-O-(2-乙酰氨基-2-脫氧-β | GlcNAc beta(1-3)GalNAc-alpha-Thr | 286959-52-2 | C20H35N3O13 |
| BETA-1,3-葡聚糖 | (2S,3R,4S,5R,6R)-2-[(2R,3R,4R,5S)-3,5-dihydroxy-2-(hydroxymethyl)oxan-4-yl]oxy-4-[(2S,3R,5S,6R)-3,5-dihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy-6-(hydroxymethyl)oxane-3,5-diol | 9012-72-0 | C18H32O14 |
| ALFHA-酸性蛋白糖 | Glycoprotein | 66455-27-4 | C28H47N5O18 |
| 6A-疊氮基-6A-脫氧-β-環糊精 | mono(6-azido-6-deoxy)β-cyclodextrin | 98169-85-8 | C42H69N3O34 |
| 3-[3,5-二羥基-6-(羥基甲基)-4-[3,4,5-三羥基-6-(羥基甲基)四氫吡喃-2-基]氧基-四氫吡喃-2-基]氧基-2,4,5,6-四羥基-己醛 | 3-[3,5-Dihydroxy-6-(hydroxymethyl)-4-[3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxyoxan-2-yl]oxy-2,4,5,6-tetrahydroxyhexanal | 3256-04-0 | C18H32O16 |
| 2,3,4,5,6,7-六羥基庚醛 | D-glycero-L-gluco-heptose | 23102-92-3 | C7H14O7 |
| —— | L-Glc(a1-4)[L-Glc(a1-6)]L-Glc(a1-4)a-L-Glc | 9005-79-2 | C24H42O21 |
| —— | [(2R,3R,4R,5R,6S)-4,5-dihydroxy-6-[[(1R,3R,4R,5S,8S)-3-[(2R,3S,4R,5R,6S)-5-hydroxy-2-(hydroxymethyl)-6-[[(1R,3S,4R,5S,8S)-3-hydroxy-4-sulfonatooxy-2,6-dioxabicyclo[3.2.1]octan-8-yl]oxy]-3-sulfonatooxyoxan-4-yl]oxy-4-sulfonatooxy-2,6-dioxabicyclo[3.2.1]octan-8-yl]oxy]-2-(hydroxymethyl)oxan-3-yl] sulfate | 9062-07-1 | C24H34O31S4-4 |
| —— | (2S,4S,5S)-2-(4-aminoimidazo[4,5-c]pyridin-1-yl)-5-(hydroxymethyl)oxolane-3,4-diol | 9013-34-7 | C11H14N4O4 |
| —— | (3R,4R,6R)-2-(hydroxymethyl)-6-[(3S,4S,6S)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxyoxane-3,4,5-triol | 9005-84-9 | C12H22O11 |
| —— | β-cyclomannin | 7585-39-9 | C42H70O35 |
| —— | β-cyclomannin | 7585-39-9 | C42H70O35 |
| —— | ZINC;1-(5-cyanopyridin-2-yl)-3-[2-(6-fluoro-2-hydroxy-3-propanoylphenyl)cyclopropyl]urea;diacetate | 9000-07-1 | C23H23FN4O7Zn |
| —— | (1S,3R,5R,6S,8R,10R,11S,13R,15R,16S,18R,20R,21S,23R,25R,26S,28R,30R,31S,33R,35R,36R,37R,38R,39R,40R,41R,42R,43R,45R,46R,47R,48R,49R)-5,10,15,20,25,30,35-heptakis(hydroxymethyl)-2,4,7,9,12,14,17,19,22,24,27,29,32,34-tetradecaoxaoctacyclo[31.2.2.23,6.28,11.213,16.218,21.223,26.228,31]nonatetracontane-36,37,38,39,40,41,42,43,44,45,46,47,48,49-tetradecol | 7585-39-9 | (C6H10O5)7 |
| —— | Cellulose triacetate | 9012-09-3 | C40H54O27 |
| —— | (1R,3R,6S,8R,11S,13R,16S,18R,21S,23R,26S,28S,30R,31R,33S,35R,40S,41S,42S,43S,44S,45S,46R,47S,48R,49S)-5,10,15,20,25,30,35-heptakis(2-hydroxypropoxymethyl)-2,4,7,9,12,14,17,19,22,24,27,29,32,34-tetradecaoxaoctacyclo[31.2.2.23,6.28,11.213,16.218,21.223,26.228,31]nonatetracontane-36,37,38,39,40,41,42,43,44,45,46,47,48,49-tetradecol | 128446-35-5 | C63H112O42 |
| —— | 2-[3,5-Dihydroxy-2-(hydroxymethyl)oxan-4-yl]oxy-4-[3,5-dihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy-6-(hydroxymethyl)oxane-3,5-diol | 9012-72-0 | C18H32O14 |
| —— | (1S,3R,6S,8R,11S,13R,16S,18R,21S,23R,26S,28R,31S,33R,37S,39S,41S,43S,45S,47S,49S)-5,10,15,20,25,30,35-heptakis(hydroxymethyl)-2,4,7,9,12,14,17,19,22,24,27,29,32,34-tetradecaoxaoctacyclo[31.2.2.23,6.28,11.213,16.218,21.223,26.228,31]nonatetracontane-36,37,38,39,40,41,42,43,44,45,46,47,48,49-tetradecol | 7585-39-9 | C42H70O35 |
| —— | Heparitin sulfate | 9050-30-0 | C14H25NO21S3 |
| —— | Glc4Me(a1-4)a-Glc1Me | 9005-82-7 | C14H26O11 |
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