| Contents: |
| Introduction |
| Reactions of Glycolysis |
| Enzymes Invovled |
| Arsinic |
| Enzymes that Are Regulated |
| Fermentation |
this is the starting material in glycolysis
Introduction
Glycolysis is one of the main processes involved in metabolism within most living substances on this earth. Glycolysis consists of 10 steps each with different enzymes. Reactions 1, 3 and 10 are more thermodynamically favorable due to their considerabley negative delta G. The magnitude of the delta G's matters. Since these three reactions are incredibly favorable that it drives all of the less favorable reactions (including step 5 and 8 which are positive delta G's) forward. So, the highly negative delta G's drive glycolysis.
Reactions of Glycolysis
Go to your blackboard sites to view the powerpoint slides of how glycolysis works. Know the enzymes involved and the molecule names and structures!!!!
Enzymes Involved
Kinase - catalyzes phosphorylation reactions and uses ATP to do it
Isomerase - causes the change to the isomer form (in glycolysis there is a change from an aldehyde to a ketone in step 2)
Aldolase - at active site there must be a + charged amino acid or a cofactor and another amino acid that is a base
- mechanism will be shown in class
Dehydrogenase - catalyzes an oxidation/reduction reaction
Mutases - moves an element to another position
Total of:
4 kinases
1 mutase
1 dehydrogenase
1 isomerase
3 enzymes that are regulated in the reaction and how and why they are regulated
Arsinic as a Substitute for phosphate:
Acts as phosphate, but skip the ATP production step, therefore are getting no ATP out of the reaction
3 Enzymes that Are Regulated;
These enzymes can be shut OFF/ON
All of these are irreversible reaction enzymes (thermodynamically favorable)
These include:
1) Hexokinase
2) Phosphofructose Kinase (PFK)
3) Pyruvate Kinase
- PKF is the most highly regulated because it is the enzyme that catalyzes the 1st committment step- it turns Glucose-6-phosphate into
fructose-6-phosphate which is the committment molecule- once it gets here, it can't go back.
Regulation of Enzymes
1) Hexokinase - inhibited by glucose-6-phosphate (increase in glucose-6-phosphate will shut it off/ decrease will turn it on)
2) Pyruvate kinase - inhibited by ATP
3) PFK - inhibited by ATP and citrate (from Kreb's Cycle)
stimulated by AMP and Fructose 2,6 - biphosphate
Fermentation
Fermentation is the process that occurs when glycolysis takes place in an anaerobic environment (w/o oxygen). In the process of
fermentation the pyruvate made from glycolysis is turned into lactate, and an NADH is oxidized to an NAD+. The oxidation of the
NADH is important because it allows the process of glycolysis to still take place in the absence of oxygen. So, 2 ATP's are made.