oses for students

oses for students

oses for students

Definition and Overview

Saccharides are also known as saccharides or carbohydrate or carbohydrate, in the form of sugar. (Greek: your gluca: sweet things)

A venture is a solid as a white crystal (not always sweet).

Formula: (CH 2 O) n

Carbohydrates are a large family of molecules abundant in plant and animal kingdoms.

The most common dare is glucose.

2 forms oses

A monomer is a power source used in the

catabolism for the degradation of glucose to pyruvate

anabolism, for the conversion of glucose to pyruvate.

A polymer allows storage of energy reserves (starch to the plant kingdom, animal kingdom for glycogen).

A polymer may also have a role structure like cellulose (wood).

Cycle oses in nature

In plants

Monosaccharides are massively synthesized by plants through the photon energy:

(h * v).

nCO2 nH2O + -> + NO2 nCH2O

The incorporation of the CO2 into carbohydrates in the form of gas will tranformer solid carbon.

Polymers are obtained from glucose formed under this porme polymer of starch or glycogen or structure such as cellulose. This reaction reduces the greenhouse effect because the CO2 is trapped in solid form.

In animals

This is the reverse reaction, i.e. aerobic metabolism that uses the O2 in the air to degrade carbohydrates.

NCH2O NO2 + -> + nH2O nCO2 Energie +

This increases the greenhouse effect. The energy produced will ensure:

Food by wheat and rice starch

herbivore feeding by the celulose.

Classification

Dare

The sugars are monosaccharides ("μονοσ σακχαρ ειδες" = only sugar down).

Monosaccharides are reducing fontion through their primary and secondary alcohol.

Osides

Osides will produce one or more monosaccharides by hydrolysis. There are several types of osides:

holosides: their hydrolysis gives dare only (di, tri, tétraholosides)

glycoside: their hydrolysis gives dare and aglycone part (non-carbohydrate).

Among the glycosides, there are:

N-glycosides: sugars + proteins amide function on the asparagine (ASN) of the immunoglobulin e.g.

O-glycosides: dare + protein on the alcohol group Serine (SER séctétion mucin in the gastrointestinal, pulmonary)

Oses occurrence in nature

Glucose and its polymers are found in the animal kingdom (glycogen) and vegetable (starch).

The glycosylation of proteins gives glycoprotein such as antibodies.

Some lipids including alcohol, may presented monosaccharides:

Glycerol: glycerolipids

Inositol: phosphatidinositol

The glycosides that contain sugars and a group aglycone, such as:

 

Part aglycone glycosides (glycoside)

Tannins Phenol (wine)

Steroid saponins (plant

Deoxyribonucleic acid nitrogen bases riboet

polycyclic Digoxin (Digitalis purpurea)

HCN Amygdalin (cores)

Monosaccharides are versatile moélcules, involved in metabolism and a wide variety of cellular functions.

The monosides: aldose and ketose

Definition

The monosides are carbon chains with hydroxyl forming primary or secondary alcohol.

(CH2O) n

  Aldose structure and ketosis

If the alcohol function is linked to an aldehyde function, the aldose is obtained

If the alcohol function is associated with a ketone function, ketoses obtained.

* Example: n = 3

For example (CH 2 O) 3 with n = 3:

Is obtained from glyceraldehyde and dihydroxyacétate.

  

Glyceraldehyde can easily pass through dihydroxyacetone enzymes:

 

Aldoses and ketoses are structural isomers of formula C3H6O3.

Ie that have identical elemental composition, but they are different molecules by their physical, chemical and biochemical.

These two compounds are known as tautomers.

Property aldoses and ketoses Commons

Ketoses and aldoses are Reducers, they can reduce metallic salts such as Ag + or Cu 2+.

 

The reaction demonstrated sugars is by Fehling: faitr which sugars react with copper sulphate CuSO4 in the presence of NaOH, and mixed sodium potassium tartrate (Rochelle salt).

Obtained an aldonic acid or carboxylate. And copper sulfate is transformed into Cu2O + 3H2O with a red coloring. So we will be able to detect sugars in a sample.

Eg Fehling

Another reaction highlighted sugars is the salt of Tollens (ammoniacal silver), which shows a silver mirror.

Nomenclature D and L

This nomenclature D and L refers to the carbon of n-1 configuration. This nomenclature of the D series and L is relative, by descent:

for aldose D and L glycéradéhyde

for ketoses D and L cétotétrose.

It is necessary to differentiate the concept of D and L or R, S with the notion of the optical rotation (+, -), which are two different concepts.

 

* D-ribose and 2-deoxy-D-ribose (Fisher)

with OH right

It is the precursor of DNA and RNA. These compounds are synthesized by the pentose phosphate pathway.

 * D-glucose in all cells

(formula)

* D-galactose, milk carbohydrates

Optical rotation carbohydrates

Pasteur shows that there are two types of tartrate crystals under polarized light:

crystal power levorotatory (-) deflection of the plane of polarized light.

crystal-handed power (+) deflection of the plane of polarized light.

Thus, 70% of carbohydrates in the series of D-aldose and 57% carbohydrate D-ketose presented deflect the light to the right. These are dextrorotatory.

A compound of the series D is not necessarily dextrorotatory.

In 1848:

Separation of two types of tartaric acid crystals of different form.

Dissolved in H2O, to deflection of the polarization plane D and G.

The tartaric acid crystals are symmetrical with respect to a mirror, and deflects light in two direction.

Explanation The beautiful and Van 't Hoff.

This is enantiomeric form. (optically active)

An atom is chiral if it has 4 different function. Reflection in a mirror (hand). It corresponds to series L and D.

Cyclic structure of monosaccharides

Cyclization of aldoses

Alcohol + Formaldehyde <-> hemiacetal

 From the time or the number of carbon atoms is greater than 5 can be obtained with an intramolecular hemiacetal fromation oxidic a bridge between C1 and C5 for example.

Alpha-D-glucose D-glucose Beta-D-glucose

 Alpha-D-glucopyranose Beta-D-pyran glucipyranose

(oxidic bridge) (baobab)

The atom C1 that was not chiral because the double bond, since it becomes chiral 4 different susbtituants. Can have 2 orintation OH C1: the top or bottom. The molecule is located on a plane with grouepement above or below the plane.

There is a training oxidic bridge between C1 and C5.

We can move from alpha to beta form form through a linear way. There is a balance between these three forms.

The alpha and beta forms are called anomeric forms related to mutarotation.

The consequence of cyclization:

C1 becomes asymmetrical, there is two times more than expected isomeric form (L or D alpha and beta D or L)

transition from one to the other by ring opening.

At pH = 7 -> 2/3 to 1/3 of alpha and beta

At pH = 10 -> 99% were linear in shape.

Ribose * Example:

Beta-D-ribose D-ribose Alpha-D-ribose

(oxy bridge)

  

Cyclization of frucose

Ketone Alcohol + <-> hemiketal

 If the carbon number exceeds 5, there may be an intramolecular hemiketal forming a bridge between oxidic C2 and C5.

Beta-D-fructose frutose D-Alpha-D-fructose

 

Beta-D-fructofuranose Furane Alpha-D-fructosfuranose

 

Saccharide derivatives

Sugar Alcohols

The existence of polyhydric alcohol is based on the reaction of reducing sugars is done with the ketone and aldehyde functional group because it is the most oxidized function.

Chimqiue way

It érduire fear in the presence of H2 in the gaseous state coupled to a catalyst and Na + amalgam and alkali borohydride (NaBH4).

Enzymatically:

H2 + D-glucose (D-fructose) -> D-sorbitol

 

D-sorbitol has a suffix itol. It is given a laxative per OS which has the advantage of not being metabolized, ie it does not cross the digestive barrier and causes an osmotic pressure. It is called a water in the intestine.

Enzymatically

H2 + D-mannose -> D-mannitol

 This mannitol is used when a head injury that often appear oedemme brain. This must be treated to prevent edema neuron degeneration.

Admistre this mannitol infusion is used. It does not cross the vascular wall and create an increase in osmalorité in the blood and increases the osmotic pressure of the vascular area.

The edema will solve for the mannitol causes calls of water in the intravascular sector, which will be discharged into the urine. This product is a diuretic because it is an osmotic diuresis.

Enzymatically

Dihydroxyacetone + H2 -> glycerol

 

Glycerol has several properties:

It is a viscous liquid which is syrupy (syrup)

Very soluble in water with the possibility of hydrogen bonding with water. He is very

used in pharmaceuticals, cosmetics thee agrochemical.

It is an emollient, it makes the sweetest thing and humectant as it moistens

(shampoo and toothpaste removes the taste of the chemical).

This is an anti-cristalisant (candy, jam)

Used as an additive to adhesives and plastic (cellophane) to avoid

drying too fast foods.

It is produced by Botrytis cinerea "noble rot" Sauternes, pleasant taste and

mellitus (tear of wine).

Starting point glycerolipids, membrane main category (from

polar).

In vivo, the glycerol is synthesized by the body through the 3P glycerol dehydrogenase enzyme that uses NADH as a cofactor and H +. It is a ubiquitous enzyme which is found in all the cells.

It converts glycerol to dihydroxyacetone.

One can make an esterification reaction on this glycerol:

alcohol fatty acid + <-> H2O + ester

récations these are the cause of glycerolipids.

Acid derivatives and lactones

Oxidation of the aldehyde function

Oxidation of the aldehyde function can be made through the liquor felhing:

This is a metallic salts by oxidation in basic medium to convert an aldehyde to carboxylate or carboxylic acid.

Oxidation of the aldehyde function may be in the presence of diode ausis I2 in basic medium.

D-glucose -> D-gluconic acid.

Oxidation of the primary alcohol function:

Example: D-glucose has a primary alcohol at the C 6.

CH2OH- (CHOH) 4-CHO + O2 -> H2O + COOH (CHOH) 4-CHO

 

D-glucuronic acid:

This oxidation reaction on the primary alcohol is in vivo. When the carbon is oxidized 6 uronic you put the suffix. It is an intramolecular esterification reactio which will bring up a oxidic bridge

We will get the delta-D-glucuronolactone

 D-delta-glucuronolactone is a lactone.

Lactone is a molecule that has an oxidic bridge and a carbonyl (C = O) next to the carbon involved in the oxidic bridge.

By intramolecular esterification is obtained a ring consisting of 5 atoms and 1 oxygen. Carbons are numbered by Greek letter from 1 carbon ajdacent carbon bearing the carbonyl C = O function.

Glucuronic acid

Role of detoxification:

 The recation glucuronidation is etherification with ether function (different ester).

Some toxic such as phenol are poorly soluble in the liquid and will physiologque be supported by this D-glucuronic acid by an etherification reaction. The glucuronic acid is activated by an acid-precursor called UDP-glucuronic increasing solubilization. A etheroyde moiety is achievable with phenol.

This gives a phenol-O-glucuronide with glucuronic-ether bond. This phenol-glucuronide is an ether oxide.

The benzene ring of phenol sparingly soluble in the aqueous solvent is water-soluble because all the hydrogen bond can be carried out with the water molecules by glucuronic acid.

Glucuronic acid thus has a detoxifying property by solubilizing all that is grafted onto it.

This reaction is catalyzed by UDP-glucuronyl transferase. This is an enzyme that can transfer a glucuronyl group from UDP-glucuronyl precursor to phenol. It is a marker of smooth Endoplasmic reticulum (especially liver)

Glucuronic acid is the basis of detoxification:

endogenous compound: steroids, thyroid hormones, bilirubin ...

exogenous xenobiotic compounds: polycyclic hydrocarbons, dixine, anti-inflammatory non-stéroïdeins (NSAIDs) ...

The excretion of the product is facilitated by an O-glucuronide conjugation with glucuronic acid, which is by two ways:

kidney

enterohepatic cycle.

Degradation of heme

Glucuronic acid is involved in the degradation of heme (tetrapyrrole ring). Heme is a degradation product of hemoglobin (lysis érythrocyrtes).

 

Red blood cells have a limited life span in time (between 100 and 120 days), beyond the globule is removed in the spleen or bone marrow (hematopoietic tissue). Heme is converted into biliverdin with rejection of Fe2 + and bilirubin (yellow coloring of plasma and urine).

Heme -> biliverdine + Fe 2+ -> Bilirubin

These two molecules are insoluble in aqueous solvents.

2 glucuronic acid grafted onto bilirubin to increase its solubility.

Hepatic enzyme bilirubin glucuronyl transferase liver will catalyze the reaction. Bilirubin becomes soluble in the aqueous solvent, or in the enterohepatic cycle épathique (or urine)

 

Medical Application:

bruise blue / green matching the insoluble when biliverdin biliverdin then becomes soluble in the lipids of the skin, blue end up disappearing.

Gilbert disease: enzyme deficiency of glucuronide conjugation causing biliverdine of deposit in the skin or brain (as very toxic lipophilic) so it is in areas where there is a lot of fat. This can disrupt the functioning of the brain.

viral hepatitis, liver enzymes that manisfeste by jaundice which is a repository of biliverdin in the skin tissue.

* Vitamin C: L-ascorbic acid

Molecular structure and forms

This is an acid of the L series (C1 carbon OH facing left), which is rare in the living.

Carbonyl bridge oxidic + = gamma-lactone

 

The L-ascorbic acid (reduced form, is an ene-diol) can easily release hydrogen 2 with their electrons and give dehydroascorbic acid (oxidized form, acid). There is a balance between these two compounds. It is a redox system with organic molecules.

The reduced form L-ascorbic acid is an antioxidant.

The L-ascrobique derived from D-glucuronic acid. Its synthesis is impossible for primates and guinea pigs. The L-ascorbic acid is a vitamin that is essential for life.

Scrobut

An acid deficiency L-ascorbic causes scurvy, which is described by J. Cartier (1536) following a long and navigation from decomposed flesh (gums and connective tissue) of the sailors who suffered from scurvy. The lime can prevent scurvy.

The disease begins in the legs because man is standing and exerts hydrostatic pressure on the legs and connective tissue surrounding the blood vessels are damaged and disintegrates, then blackened.

Physiological roles of vitamin C:

Hydroxylation of proline

Procollagen -> collagen.

Pro-> Hyp

Proline is an essential constituent of collagen and procollagen. The hydroxylation of proline is a posttranslational modification of the procollagen of collagen that becomes. Proline is converted to hydroxy-proline. This reaction is catalyzed by the procollagen-proline hydroxylase enzyme which acts with a co-factor is vitamin C.

3 molecules colagene wrap to a triple helix:

Hydroxyproline allows stablilisation of the collagen triple helix as it has the hydroxyl of the vitamin C in addition to which hydrogen bond to the cohesion of the molecule.

The tripeptide is used (Pro-Pro-Gly) that is found in the collagen molecule. Without hydroxylation of proline, the Tm is 24 ° C.

If the hydroxyl proline second one has a Tm of 58 ° C.

So cohesion is much more important.

Without vitamin C, the enzyme reaction does not work and was the colagene not hydroxylated proline. It takes much less colagene and loses its mechanical characteristic.

Scurvy is:

less hydroxyproline

decrease the Tm of colagene

alteration of the connective tissue

fragility vacsulaire

Treatment:

fruits and vegetables

lime

Protection against oxidative stress

cellular respiration is causing oxidative stress. Some cells are formed to induce oxidative stres, tellesque macrophages. These produiset mol of superoxide ion, which is involved in the innate defense against infection.

Same process found in the mitochondria.

This is a pathophysiological phenomenon.

This is because we are physiological be aerobic (use of O2) with mitochondria that synthesized energy.

We have anti-infectious defenses, which is innate imunité (use of O2 by PolyNucléaireNeutrophile and macrophage).

This mechanism produces superoxide ions that is a free radical with unpaired electrons. It is a highly reactive molecule. Is designated as a period followed by a negative charge.

The superoxide ion very quickly interacts with the membrane lipid peroxidizing, making them unstable and causes degradation.

To avoid degradation of lipids, vitamin C and vitamin E are involved.

Vitamin E will recover the extra electron, giving vitamin E radical. She will break the bond of the lipid superoxide to reform the basic membrane lipids.

Ascorbic acid will recover this unpaired electron in the form of ascorbate radicaire that will be eliminated in the urine.

 Vitamin C helps:

regeneration of oxidized lipids,

less lipid peroxidation

the regeneration of vitamin E

decrease the effect of oxidative stress.

 Radical semidéshydroascorbyl strong electro-negativity that allows cappture iron. Vitamin C has a well electron to fix the unpaired electron.

Chelation ferrous iron Fe 2+

Vitamin C allows the chelation of iron and copper. Vitamin C has anti-debilitating role she fight against iron deficiency anemia in fixing the Fer2 + in the intestine and promotes its passage through the intestinal barrier.

Ester derivatives of monosaccharides

Primary alcohol

Alpha-D-glucose + ATP -> alpha-D-glucose-6P + ADP.

Important in glycolysis. Esterification carbon 6 of D-glucose.

 

Semi-acetal function

The précursuer UDP-alpha-D-glucose allows glucose metabolism with an esterification of the semi-acetate function.

 

Disaccharide or diholosides

These are 2 dare réunient by a glycoside or glycoside bond.

 

The first has a dare yl suffix.

Glycoside bond between two carbon number n and m.

The second venture has a suffix:

Oside when it has no reducing power

When he dares a reducing power.

Formation of the glycoside bond

It requires a condensation loss of water molecule:

it is impossible between 2 primary and secondary OH

It is possible between 2 OH worn by hemiacetal function there will be a loss of reducing power (n and m anomeric). One thus obtains a Oside.

It is common between a hemiacetal and a secondary OH OH, (m non anomer). The result is a dare.

Lactose

Chemical synthesis of lactose

D-glucose + D-galactose -> lactose H2O +

 

Condensation

The reverse reaction is catalysed by the enzyme lactase which is not always active at birth. An absence of lactase gives a lactose intolerance.

Lactose is a reducing anomer because the free D-glucose is a monosaccharide and not a glycoside.

Is obtained Galactose-beta (1-> 4) glucose.

 Beta-D-galactopyranosyl (1-> 4) -D-glucopyranose

Between galactose and glucose there is a difference in the positioning of the OH from the plane of the molecule. On galactose was down-up-up while on glucose was low-high-low. These two compounds are epimers.

Enzymatic synthesis of lactose

The lactose hydrolysis is about 800 times easier than its synthesis.

The enzymatic synthesis is carried out in the mammary gland by activation of a precursor (monomer) with enzyme: lactose synthase. Mammary gland (50 g / L)

Must activation by ATP-beta-D-galactose resulting from beta-D-galactose-1P, which will then be activated by UTP to give lactose.

 

It is a reaction that requires energy:

activate a monomer.

UDP derivative energy-rich

Enzyme allows the decrease in activation energy

This synthesis is not done from a model unlike the synthesis of mRNA or protein.

Non-reducing disaccharides

maltose: Basic dimer produced during the hydrolysis of the Midon and glycogen.

Non réducteus diholosides

Sucrose or sucrose were brought back from the east by the campaigns of Alexander the Great (sugar cane, beet, ...).

Sucrose or sucrose is because the non-reducing anomeric 2 carbons are stuck in the glycoside bond.

 

Alpha -D-Glucopyranose

GLC alpha1 -> 2 fru

Beta -D-fructofuranose

alpha-D-glucopyranosyl (1-> 2) Beta-D-fructofuranoside

Polysaccharides

Classification

These are polymers of monosaccharides:

supporting role or reserve

associated with portéines, fat ...

Homogeneous polysaccharide

They all sound consists of a single type of monosaccharides. These are derived from D-glucose:

glucan glucose derivative (cellulose, starch, glycogen)

mannan derived from D- mannose

Heterogeneous polysaccharides 2 types of dare

Galactomannans

Heterogeneous polysaccharides to monosaccharides

- Pets: mucopolysaccharides

- Vegetable: fums, mucilage (agar)

Spatial structure of polysaccharides

Osidic Alpha Link

Example: alpha (1-> 4): starch, glycogen

 This is an inclined connecting two glucose linked by a glycosidic bond with an angle of 140 °. Therefore obtained a helical structure with alpha-glycoside.

Beta-glycoside

 It is a linear strcuture shape with an angle of 180 °.

Homopolyoside reserve

Location glycogen

Demonstrated by Bernard C. (1856) in the liver.

If one has excess glucose, it will bind to glycogen granules. If there is a demand for glucose, it will be released by glycogen granules in the vicinity of the REL.

 

Starch structure

 Starch is the cause of "sugars": 2 molecules.

 

Alpha amylose (20%) Amylpectine (80%)

D-glucose polymer ditto

Unbranched branched.