CHO chemistry

general formula of carbohydrates

Cn(H20)n

structure of carbohydrates

* polyhydroxy aldehydes (multiple OH groups)


* ketones ( C=O with 2 diff r groups)
* or substances that yield such compounds through hydrolysis

function of carbohydrates

* energy (4kCal/g)
* storage form
* structural component of cell

clinical function of carbohydrates

* cardiac glycosides
* medicated heart failure and irregular heartbeat
* antibiotics
* dietary fiber
* intravascular coagulant

monosaccharides classification and ex

* if functional group is an aldehyde: aldoses
* ex. glucose
* if functional group is a keto: ketoses
* ex. fructose

monosaccharides structure

Fischer (page) or Haworth (cycle)

\
Haworth:

* 6 membered ring → pyranoses
* 5 membered ring → furanoses

stereoisomers

* same chemical formula but differ in positions of hydroxyl groups on asymmetric carbons
* ex. glucose, galactose, and fructose

enantiomers

* can exist in either of 2 conformations
* determined by hydroxyl orientation about the asymmetric carbon
* right: D
* left: L
* carbs w physiological significance exist in D
* ex. D-glyceraldehyde & L-glyceraldehyde

epimers

* differ in OH placement not around the asymmetric carbon
* ex. glucose and mannose with regard to C-2

anomers

* in cyclization (haworth projection)
* alpha: OH is trans to CH2OH
* beta: OH is cis to CH2OH
* ex. alpha- gucose and beta- glucose differ only around the anomeric carbon (C1)

optical isomers

differ in direction in which plane rotates (?)

* positive/clockwise: dextrorotatory
* negative/couterclockwise: levorotatory
* ex. dextrose and levulose

properties of sugars

* muta rotation
* reducing property
* sugar oxidation
* reduction to form alcohols
* glycosides
* formation of esters

disaccharide linkage

* glycosidic linkage
* alpha or beta bond formed through a dehydration reaction

digestion of glycosidic bonds

* alpha bonds: digestible
* beta: indigestible, absence of specific enzymes

disaccharides examples (4)

* sucrose
* maltose
* isolmaltose
* (cellobiose)

maltose make up

2 alpha-glucose residues\`

maltose yields (with maltase)

2 glucose residues

maltose use

intermediary in acid and enzyme hydrolysis of starch

maltose properties

* reducing properties
* forms osozones (sunflower appearance)

lactose structure

beta glucose and galactose residues

lactose yields (with lactase)

glucose and galactose residues

lactose properties

* milk sugar
* reducing properties
* forms osozones (powderpuff/ hedgehog appearance)

lactulose

* non absorbable synthetic disaccharide
* made up of galactose and fructose units
* used to treat constipation or hepatic encephalopathy

sucrose structure

alpha glucose and beta fructose residues

sucrose properties

* table sugar
* non reducing
* no osozones

sucrose yields (with sucrase)

glucose and fructose residues

invert sugar

* sucrose is dextrorotatory, but its hydrolytic product is levorotatory
* resulting mixture of fructose and glucose is invert sugar
* ex. honey (fructose → sweet taste)

oligosaccharides examples (2)

raffinose: glucose, galactose, and fructose

stachyose: 2 moles glacatose, glucose, and fructose

oligosaccharides origin

usually plant origin

polysaccharides classifications

* homopolysaccharides
* heteropolysaccharides

starch structure

multiple alpha D glucose

starch properties

* carbohydrate reserve in plants
* important dietary fiber

starch components

amylose and amylopectin

amylose properties

* water soluble
* unbranched
* blue colour with iodine

amylopectin properties

* water insoluble
* branched
* violet colour with iodine

starch yields (with amylase)

* dextrin
* which yield maltose and glucose

cellulose presence

* only in plants
* indigestible for humans

cellulose properties

* major constituent of dietary fiber
* role in:
* diabetes
* lipid profile
* constipation

cellulose structure

beta D glucose residues by beta glycosidic bonds

glycogen significance

* animal reserve of body

glycogen structure

alpha D glucose residues

glycogen presence

high in liver, muscles, & brain

inulin

* not used up by body; used to assess kindey functions (GFR)


* present in garlic, onion, etc.
* fructose polymer


* easily water soluble

dextrans

* plasma expander
* given in cases of hemorrhage

chitin

* found in exoskeleton of some invertebrates

hyaluronic acid

* only non-sulphated GAG
* lubricant and shock absorbent in joints

chondroitin 4 and 6 sulphate

* most abundant GAG
* loss of it in cartilage causes osteoarthritis

heparin

* anticoagulant
* intracellular component of mast cells lining arteries, lung, and skin

dermatan sulphate

* found in skin; blood vessels and heart valves

keratan sulphate

* found in cornea
* responsible for corneal transperancy

proteoglycans

95:5 protein:carbohydrates

glycoproteins

less than 10% carbohydrate content

example of glycoprotein

antibody

* carbohydrate part plays role in determining where antibody binds

pectin and hemicellulose function

jelling agents

hyaluronic acid function

cementation in tissues and lubrication

heparin function

anticoagulant

keratin sulphate function

present in cartilage and cornea

* responisble for corneal transparency

glycosides function

used as drugs

dextrose

form of glucose given intravenously with specific requirements

mannitol

sugar used to relieve intracranial tension

* bc of osmotic diuretic properties