Week 1 Flashcards
Oxidation-Reduction class of enzyme
Oxidoreductases
e.g.. Lactate Dehydrogenase
Group transfer class of enzyme
Transferases
additional or removal of groups to form double bonds
Hydrolases
Isomerization (intermolecular group transfer) class of enzyme
Isomerases
Enzymes that act with Ligation of two substrates at the expense of ATP hydrolysis
Lipases
Enzyme with its cofactor.
Holoenzyme
protein portion of the holoenzyme.
Apoenzyme
tightly bound coenzyme that does not dissociate
Prosthetic group
What do enzymes do to help a reaction move forward?
They Lower the energy of activation, and create favorable orientation of the substrates to react to form product.
Rate of reaction is directly proportional to [E] at all [S]. E.g. If [E] halved, Vo reduced to one half of original.
Michaelis-Menten Kinetics
What is Km?
reflects the affinity of E for S.
Equivalent to [s] at with Vo is Equal to 1/2 Vmax
________is a response of an enzyme to an effector molecule that results in an increase or decrease in its activity
Allosterism
Inhibition reversed by increasing [S]. At a sufficiently high [S] the reaction velocity reaches the Vmax observed in absence of Inhibitor.
Competitive Inhibitors
increases the apparent Km-max for a given S. More substrate is needed to achieve 1/2 V
Vmax itself is not effected.
Competitive Inhibitors
2-12 monosaccharides
Oligosaccharides
Differ only
in configuration
around a single
carbon atom
Epimers
is a cyclic saccharide and an epimer that differs in configuration, specifically at the hemiacetal/acetal carbon, also called the anomeric carbon.
Anomers
e.g.. alpha and beta Glucose
An __________ bond is formed when the OH group attached to an anomeric carbon condenses with a group on another monosaccharide
O-glycosidic
Beta Lactose Bonds
Galactose B1-4 Glucose
Sucrose bonds
Glucose a1-2 Fructose
Maltose bonds
Glucose a1-4 Glucose
Glycosidic bonds (glycogen)
α-1,4- and α-1,6-(branch)
Amylose Bonds
a 1-4
______is the helical form of starch comprised only of _____linkages, and______ has a structure like glycogen except that the branched_____ linkages are present on only about one in 30 monomers.
amylose, alpha-1,4
amylopectin, alpha-1,6
Brush Border Enzymes
- Sucrase
- Lactase
- Maltase
- Isomaltase
- a-maltase (breaks a,1-6)
Passage of undigested carbohydrate into large intestine, results in:
- Osmotic diarrhea.
- Bacterial fermentation of carbohydrate to 2 and 3 C fragments plus CO2 and H2
gas
Congenital Sucrose Intolerance.
Sucrase-Isomaltase Deficiency is also known as SI Deficiency, Disaccharide Intolerance I
10% of Greenland’s Eskimos deficient
_________ is able to attach to the tooth surface and form a biofilm.
The______ slime can be depolymerized to glucose resulting in production of lactic acid
S. mutans
dextran
GLUT__ (high affinity) brain and rbc
1
GLUT__ liver, kidney, intestine and β cells
2
GLUT __nearly all cells
3
GLUT__ insulin- dependent isoform present in muscle and adipose
4
GLUT __ small intestine on arterial side of the epithelial cell.
5
Active transport areas for Glucose.
Epithelia of small intestine
Renal Tubules
Choroid Plexus
Insulin Insensitive tissues
- Epithelia of small intestine
- Renal Tubules
- Choroid Plexus
- Erythrocytes
- lens of eye
- liver
- Brain
In the Lumen of the small intestine cotransport of glucose is mediated by a Na+ glucose symporter ______
SGLT1
Glucose Newly Arrived in the Cell is Phosphorylated by
Hexokinase
Products of Glycolysis for one glucose molecule
2 ATP(net)
2 NADH
2 Pyruvate
Under anaerobic conditions pyruvate is reduced to lactate with the concomitant oxidation of_____ to ______ to allow for the continuation of glycolysis
NADH
NAD+
Instead of Hexokinase Glucokinase is found in
Liver and β cells
Allosterically inhibited by Glucose 6 phosphate.
Hexokinase
adds Pi to Phosphoenolpyruvate (PEP) to make Pyruvate
Pyruvate Kinase