Ch_14_Cyclic Structures of Monosaccharides

8/17/2019 Ch_14_Cyclic Structures of Monosaccharides

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Chapter 14.3

Cyclic Structures of Monosaccharides


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Monosaccharides in Nature

The linear form of monosaccharides isinstable - only 1%

C5 and C6 carbs form Hemiacetal or cyclicalform, ringform – 99%Sugars open and close randomly, fre uently

!ntermolecular rearrangement


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HemiacetalsGlucose: "ydro#yl group connects$ C5 → C1 forming a

1,5 ether lin a!e.Not a dehydration "ut a rearran!ement###


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cycli ation of glucoseCycli ation of glucose &

"ay'orth pro(ection

http://www.bing.com/videos/search?q=glucose%20ring%20closure%20animation&qs=n&form=QBVR&pq=glucose%20ring%20closure%20animation&sc=0-20&sp=-1&sk=http://www.bing.com/videos/search?q=cyclization%20of%20glucose&qs=n&form=QBVR&pq=cyclization%20of%20glucose&sc=3-22&sp=-1&sk=http://www.bing.com/videos/search?q=cyclization+of+glucose&FORM=HDRSC3&adlt=stricthttp://www.bing.com/videos/search?q=cyclization+of+glucose&FORM=HDRSC3&adlt=stricthttp://www.bing.com/videos/search?q=cyclization%20of%20glucose&qs=n&form=QBVR&pq=cyclization%20of%20glucose&sc=3-22&sp=-1&sk=http://www.bing.com/videos/search?q=glucose%20ring%20closure%20animation&qs=n&form=QBVR&pq=glucose%20ring%20closure%20animation&sc=0-20&sp=-1&sk=


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Hay$orth Structure of Glucose


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C1 :non%chiral in linear form"ut chiral in rin!: la"eled & or '


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Num"erin! Car"ons onHemiacetals

)l'ays start on the right hand side

1,5 *ther +in age


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Cyclic Structure of Galactose

alactose is an aldohe#ose that differs fromglucose only 'ith the –." group on carbon /

0ith formation of a ne' hydro#yl group oncarbon 1 – galactose also e#ists in 2 3 forms

4- alactose α- alactose β- alactose


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Cyclic Structure of (ructose

ructose is a etohe#ose$ C5 reacts 'ithetone group C

Smaller ring$ pentagon


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(ructose )in! num"erin!

,5-ether lin age


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Chapter 14.5

*isaccharides


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Glycosidic "ond formation


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Namin! of Glycosidic /onds:Maltose

Carbon @ of first sugar connected to Carbon@number of second sugar

7altose$ C1 is connected to C/C1 is also in & position

0riting con;entions$

81,/: glycosidic bondor alpha 81-/: A


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More e amples


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0ther !lycosidic "onds

"eta -1%4 !lycosidic "ond

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3 *isaccharides you need tono$1? 7altose – malt sugar

? +actose – mil sugar B?

Sucrose - table sugar

enerally, a disaccharide ischaracteri ed by>?1? 7onosaccharide components

? glycosidic bonds


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Maltose

7onomers$ 1? -4- lucose ? or 3-4- lucoselycosidic bond$ 81-/:

Creating t'o chiral ;ersions of 7altose 3 7altose 7altose

' -4-7altose &-4-7altose

3 of maltose is determined by the C1 position of

second sugar


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hat2s Maltose Malt Su!ar

.btained from thehydrolysis of starch

Dsed in cereals,candies, and bre'ingof be;erages


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+actose

7onomers$ 3-4-galactose 'ith - 3-4-glucose

lycosidic bond$ 3 81-/:Creating t'o chiral ;ersions of +actose

' -4-+actose &-4 -+actose

http://www.google.com/imgres?q=lactose+structure&hl=en&safe=active&tbo=d&biw=1280&bih=571&tbm=isch&tbnid=v6KlBn2AL-BJxM:&imgrefurl=http://users.bergen.org/dondew/bio/AnP/Anp1/AnP1Tri1/CARB_ART/LACTOSE_SYNTH/LactoseSynth.html&docid=GIpj14H8eeKCQM&imgurl=http://users.bergen.org/dondew/bio/AnP/Anp1/AnP1Tri1/CARB_ART/LACTOSE_SYNTH/Fig2lactose.gif&w=304&h=161&ei=nx4IUbbHIcjmigKwjoGoCQ&zoom=1&iact=hc&vpx=827&vpy=325&dur=2391&hovh=128&hovw=243&tx=129&ty=82&sig=112028049467032634653&page=1&tbnh=128&tbnw=243&start=0&ndsp=18&ved=1t:429,r:16,s:0,i:128


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+actose

7a es up 6-E% of human mil and

/-5% of co'Fs mil+actose intolerance$ lac of the en ymelact ase that splits disaccharide duringdigestion

dult Mammals stop e#pressing the lactasegene – e#ception$ many adult humans ha;ede;eloped a lactose tolerance

8microe;olution: but depends on ethnicity


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Sucrose

7onomers$ -4-glucose and 3-4-fructoselycosidic bond$ ,3 81, :

Creating only one formof 4-Sucrose


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Sucrose

Commercial sugar, obtained from sugarbeets and sugar cane


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Chapter 14.

6olysaccharides


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6olysaccharides

) polymer of many monosaccharides (oinedtogether$ glycosidic bd!mportant polysaccharides$1. mylose7 mylopectin –plant starch8. Glyco!en – animal starch3. Cellulose – plant fibers

7onomers$ all *%!lucose but differentglycosidic bonds


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mylose7 mylopectin

Common name starchesglucose storage in plant seeds, tubers etc

ound in grains, potatoes, beans, fruitsSoluble in 'ater Commercial Starch$ mi#ture amylose G%

and amylopectin EG%


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mylose

7onomer$ &%*%!lucose 8about GG-/GGG:lycosidic bond$ &%1,4%G/

*n yme brea ing it$ mylaseStructure$ +ong helical chain


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mylopectin

7onomer$ &, *%Glucoselycosidic &ond$ & -1,4 and & -1, &8e;ery 5 glucose monomers:

*n yme brea ing it$ amylase iso9ymesA/ranched starch H


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Glyco!en

)nimal starchStorage of glucose in the li;erSimilar to amylopectin only more branches8e;ery 1G-15 glucose molecules:


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Cellulose

7onomers$ ',*%!lucoselycosidic bond$ '1,4%!lycosidic "onds

*n yme brea ing it$ Cellulase

!nsoluble in 'ater straight strands, found in the cell 'all ofplants, ma e plant stal s rigid and strong

"umans, animal, plants *0 N0 H ;< theen yme cellulaseonly bacteria li;ing in the guts of ruminants

ha;e cellulase


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*i!estion of Cellulose

ra ing animals and termites harbor e-coli'ho digest cellulose for them

!n humans cellulose helps absorb to#ins fromdigestion of proteins to maintain a healthydigesti;e system


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Car"ohydrates in 0ur *iet


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Hydrolysis

Chemical reaction to separate polymers byinserting a 'ater molecule

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Ch_14_Cyclic Structures of Monosaccharides