Descriptive Study of Oses’biological interest and their derivatives

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1) D-Glucopyranose :

  • Se glucose naturel (D (+) glucose) is widespread in nature. This is the main fuel of the body and the universal fuel of the fetus.
  • the polymerization of glucose leads to glycogen (foie, muscles).
  • glucose is the glucose concentration in the free state in the blood (0.80g/l )
  • glucose is reducing, glucose oxidase oxide in aldonic acid

Glucose oxydase
Glucose ————————–► gluconic acid + H20
Cœnzyme

  • its optical rotation is dextrorotatory.
alpha-D-Glucopyranose

2) D-Galactopyranose :

  • It is involved in the composition of :

– lactose = D Gal + D Glu cérébrogalactosides brain.

-glycoproteins and glycolipids some.

  • Its optical rotation is dextrorotatory.

3) D-Mannopyranose :

  • it is present mainly in plant.
  • It is a constituent of glycoproteins in humans.
  • Its optical rotation is dextrorotatory.

4) D-Fructofuranose :

  • It is found mostly in his name where fruit.
  • Its optical rotation is levorotatory hence his name of levulose.
  • It is present in seminal fluid in humans or participates in the movement of sperm.
  • It is present in form furan sucrose.
  • the cyclisation is between C2(ketone)and C5 .

NB : position of the substituents on the C2 :

  1. first placed oh hemiacetal which gives the configuration or ,
  2. The in CH20H 1 takes the vacant position.

5) D-Ribofuranose :

  • the furan form is the usual form of combined pentoses in nucleic acids (ARN).
  • D ribofuranose is related to the purine and pyrimidine bases through an N-glycosidic bond (nucleosides, nucleotides).
  • He intervenes in the structure of coenzyme : OVER,NADP,ATP .

*The organic form is the form furan(1-4)

In deoxyribose the OH 2 is replaced with H (ADN)

alpha-D-Ribofuranose
Beta-D-Ribofuranose

6) Amine derivatives of organic oses :

  • Two amino sugars have biological interest : glucosamine (-OH, and 2 replaced by -NH2)
  • The NH2-acetylated is often to give a N-acetylglucosamine or N-acetylgalactosamine
  • The amino sugars are components of glycolipids, glycosaminoglycans and glycoproteins.
Beta-D-Glucosamine / Beta-D-N-Acetyl-Galactosamine

7) Acid derivatives d’biological dares :

a- aldonic acids :

by oxidation are obtained from the hemiacetal function of aldoses by halogen(ketoses do not react)

b- uronic acids :

– are obtained by oxidation of the primary alcohol function to the C6

  • These are glycosaminoglycans constituents
  • Their biological role is essential in liver detoxification

c- = Sialic acid N-acetyl neuraminic acid(NANA) :

* The neuraminic acid is the condensation product of :

pyruvic acid + D-mannosamine.

  • These are components of glycoproteins and glycolipids of eukaryotic cells wall.

During the DR ZEKRI.S – Faculty of Constantine

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