Overview of carbohydrate metabolism

Overview of carbohydrate metabolism
Presentation by: Dr. Nuran Ercal

GLYCOLYSIS
* Glycolysis occurs in almost every living cell.
* It occurs in cytosol.
* It was the first metabolic sequence to be studied.
* Most of the work done in 1930s by the German biochemist G. Embden Meyerhof Warburg.
* That is why it is also called Embden-Meyerhof pathway.
* It is a greek word.
* Glykos------> sweet
* Lysis-------> loosing
* Glycolysis-----------> loosing or splitting of glucose
* Glc is an important fuel for most organisms.
* Why is Glc chosen?
* 1) Glc is one of the monosaccarides formed formaldehyde
* under prebiotic conditions.
* 2) Glc has a low tendency to glycosylate proteins
* Fermentations provide usable energy in the absence of oxygen
* Why is a relatively inefficient metabolic pathway so extensively
* used?
* Answer: It does not require oxygen
* Obligate anaerobes
* Facultative anaerobes
* 3 of the reactions of glycolysis are irreversible.
* Pyruvate is the end product of glycolysis in tissues with mitochondria.
* This series of 10 reactions called aerobic glycolysis,

Stages of glycolysis
* Stage I
* Goal: To trap the Glc in the cell

IMPORTANCE OF PHOSPHARYLATED INTERMEDIATES
PHOSPHORYLATION OF GLUCOSE
Induced fit in Hexokinase
Difference between hexokinase and glucokinase
Hexokinase vs glucokinase
SUMMARY
More about HK
* Hexokinase, like adenylate kinase and all other kinases, requires Mg (or Mn) for activity.
* Hexokinase is also one of the induced-fit model enzymes.
* It has two lobes that move towards each other when Glc is bound!
* Substrate-induced cleft closing is a general feature of kinases.
* Other kinases (Pyruvate kinase, phosphoglycerate kinase and PFK) also contain clefts between lobes that close when substrate is bound.

2. ISOMERIZATION OF G-6-P
3. PHOSPHORYLATION OF F-6-P
4. CLEAVAGE OF F-1,6BIP
5. ISOMERIZATION OF DIHYDROXYACETONE-P
6. OXIDATION OF GLYCERALDEHYDE 3-P.
Structure of glyceraldehyde 3-phosphate dehydrogenase
7: FORMATION OF ATP FROM 1,3-BIPGLYCERATE AND ADP
Q:Why does PEP have such a high P-ryl potential?
Pyruvate kinase deficiency:
Maintaining redox balances

Overview of carbohydrate metabolism.ppt