BICH 411

1. irreversible
2. 1st committed step
3. catabolic/anabolic pathways differ
4. compartmentalization

1. oxidation/reduction (oxidoreductases)
2. C-C bond breaking/making (hydrolases, lyases, ligases)
3. rearrangements, isomerizations, and eliminations (isomerases and mutases)
4. group transfer (transferases and hydrolases)

1. supply of substrates/removal of products
2. activities of enzymes

Q~Keq; readily reversible
regulation = concentrations of substrates/products

ex: creatine kinase
nucleoside diphosphate kinases

Q > or < Keq; far from equilibrium
regulation = changes in catalytic activity through ALLOSTERIC REGULATION

direct transfer of phosphoryl group from high energy compound

ex: kinases

ATP generated indirectly using eneryg from proton concentration gradients

ex: GAP DH (NAD-->NADH)

1. less change in repulsion of products
2. more resonance stabilization in products
3. products rapidly ionize

used to regenerate ATP rapidly in muscle/nerve cells

creatine+ATP <--(creatine kinase)--> phosphocreatine+ADP

generate phosphocreatine when at rest
break down phosphocreatine when working out

ATP+NDP <---> ADP+NTP

found in all cells

2 ADP <---> AMP + ATP

glucose+ATP --> G6P+ADP
Mg2+
HK=muscle
(-) G6P
higher affinity/lower Km

GK=liver
lower affinity

G6P <---> F6P

acid-base catalysis
cis-endiol intermediate

F6P+ATP ---> F16BP+ADP
Mg2+
allosteric:
(+) AMP, F26BP
(-) ATP, citrate

F16BP<--->GAP+DHAP
Class I=animals
-covalent schiff base intermediate
-active site lysine/Aspartate

DHAP<--->GAP

ketose<-->endiol intermediate<-->aldose

acid-base mechanism
(-)Transition state inhibitors
phosphoglycohydroxymate
2-phosphoglycolate

GAP+NAD+Pi <----> 1,3-BPG+NADH+H

oxidative phosphorylation
thiohemiacetal/acylthioester intermediates

1,3-BPG+ADP <---> 3-PG+ATP
Mg2+
substrate-level phosphorylation

3-PG<--->2-PG
active site=unique phosphorylated histidine

2-PG<--->PEP+H2O
dehydration
inhibitor=Fluoride ion

PEP+ADP--->Pyruvate+ATP
Mg2+/K+
substrate-level phosphorylation
enolpyruvate intermediate
tautomerization
covalent:(liver)
(-)glucagon [phosphorylation]
allosteric:
(+) F16BP
(-) ATP, acetyl-CoA, LCFA, alanine

F16BP+H2O--->F6P+Pi

allosteric:
(+) citrate
(-) AMP, F26BP

Pyruvate+HCO3-+ATP--->OAA+ADP+Pi
(in mitochondria)
prosthetic group-BIOTIN (CO2 carrier)
active site=biotinyl-lysine, bicarbonate

OAA+GTP--->PEP+GDP+CO2
in mitochondria:malate/asp shuttle

OAA+NADH--(malate DH-mitochondria)-->malate+NAD--(malate DH-cytosol)-->OAA+NADH

OAA+AA--(aminotransferase-mitochondria)-->Aspartate+alpha-KA--(aminotransferase-cytosol)-->OAA+AA

G6P+H2O-->Glucose+Pi
only in liver

G6P(cytosol)--(T1)-->G6P(lumen)-->glucose(lumen)--(T2)-->glucose(cytosol)--(GLUT2)-->glucose(extracellular)

ATP binds to substrate site
ATP binds to inhibitor site

ATP binds to substrate site
F6P binds to substrate site
AMP binds to inhibitor site

ionic interaction b/w Arg and F6P

F6P+ATP--->F26BP+ADP
covalent:
(+) insulin
(-) glucagon

PEP+ADP--->Pyruvate+ATP
Mg2+/K+
substrate-level phosphorylation
enolpyruvate intermediate
tautomerization
covalent:(liver)
(-)glucagon [phosphorylation]
allosteric:
(+) F16BP
(-) ATP, acetyl-CoA, LCFA, alanine

F16BP+H2O--->F6P+Pi

allosteric:
(+) ATP, citrate
(-) AMP, F26BP

Pyruvate+HCO3-+ATP--->OAA+ADP+Pi
(in mitochondria)
prosthetic group-BIOTIN (CO2 carrier)
active site=biotinyl-lysine, bicarbonate

OAA+GTP--->PEP+GDP+CO2
in mitochondria:malate/asp shuttle

OAA+NADH--(malate DH-mitochondria)-->malate+NAD--(malate DH-cytosol)-->OAA+NADH

OAA+AA--(aminotransferase-mitochondria)-->Aspartate+alpha-KA--(aminotransferase-cytosol)-->OAA+AA

G6P+H2O-->Glucose+Pi
only in liver

G6P(cytosol)--(T1)-->G6P(lumen)-->glucose(lumen)--(T2)-->glucose(cytosol)--(GLUT2)-->glucose(extracellular)

ATP binds to substrate site
ATP binds to inhibitor site

PEP+ADP--->Pyruvate+ATP
Mg2+/K+
substrate-level phosphorylation
enolpyruvate intermediate
tautomerization
covalent:(liver)
(-)glucagon [phosphorylation]
allosteric:
(+) F16BP
(-) ATP, acetyl-CoA, LCFA, alanine

ATP binds to substrate site
F6P binds to substrate site
AMP binds to inhibitor site

ionic interaction b/w Arg and F6P

F16BP+H2O--->F6P+Pi

allosteric:
(+) citrate
(-) AMP, F26BP

Pyruvate+HCO3-+ATP--->OAA+ADP+Pi
(in mitochondria)
prosthetic group-BIOTIN (CO2 carrier)
active site=biotinyl-lysine, bicarbonate

F6P+ATP--->F26BP+ADP
covalent:
(+) insulin
(-) glucagon

OAA+GTP--->PEP+GDP+CO2

OAA+NADH--(malate DH-mitochondria)-->malate+NAD--(malate DH-cytosol)-->OAA+NADH

OAA+AA--(aminotransferase-mitochondria)-->Aspartate+alpha-KA--(aminotransferase-cytosol)-->OAA+AA

G6P+H2O-->Glucose+Pi
only in liver

G6P(cytosol)--(T1)-->G6P(lumen)-->glucose(lumen)--(T2)-->glucose(cytosol)--(GLUT2)-->glucose(extracellular)

ATP binds to substrate site
ATP binds to inhibitor site

ATP binds to substrate site
F6P binds to substrate site
AMP binds to inhibitor site

ionic interaction b/w Arg and F6P

F6P+ATP--->F26BP+ADP
covalent:
(+) insulin
(-) glucagon

F26BP+H2O--->F6P+Pi
covalent:
(+) glucagon
(-) insulin

long-term maintenance of steady-state BG levels
-initiates PHOSPHORYLATION cascades
(+) liver gluconeogenesis
(+) glycogen breakdown
**liver and adipose only

released in response to high BG
initiates DEPHOSPHORYLATION cascades
(-) liver gluconeogenesis
(+) glycogen synthesis

glycogen phosphorylase A --> glycogen phosphorylase B
phosphorylase kinase A --> phosphorylase kinase B

dephosphorylation
covalent: (+) insulin

activates FBPase-2
deactivates PFK-2

phosphorylation
covalent: (+) glucagon, cAMP

pyruvate+NADH<--(lactate DH)-->lactate+NAD

anaerobic
lactic acid fermentation in muscles/ cori cycle

active site= Arg and Lys

1. pyruvate--(pyruvate decarboxylase/TPP)-->Acetaldehyde+CO2
2. acetaldehyde+NADH<--(alcohol DH)-->ethanol+NAD

1. acetaldehyde+NAD<--(aldehyde DH)-->acetate+NADH

muscles:
fructose+ADP--(HK)-->F6P
liver:
1)fructose+ADP--(FK)-->F1P
2)F1P--(F1P aldolase)-->DHAP+glyceraldehyde
3. glyceraldehyde--(glyceraldehyde kinase)-->GAP
4. glyceraldehyde+NADH--(alcohol DH)-->glycerol+NAD
5. glycerol+ATP--(glycerol kinase)-->glycerol3P+ADP
6. glycerol-3-P+NAD--(gly-3-P DH)-->DHAP+NADH

1. galactose+ATP--(galactokinase)-->Gal-1-P+ADP
2. Gal-1-P+UDP-glucose--(UDP-glu uridyltransferase)-->UDP-gal+Glu-1-P
3. UDP-gal--(UDP-gal-4-epimerase)-->UDP-glucose
4. Glu-1-P<--(phosphoglucomutase)-->G6P

1. mannose+ATP--(HK)-->M6P+ADP
2. M6P--(phosphomannose isomerase)-->F6P

GAP+AsO4+NAD--->1-arseno-3PG+NADH

1,3BPG--(BPG mutase)-->2,3BPG
2,3BPG--(2,3BPG phosphatase)-->3PG+Pi

this pathway makes net ATP of glycolysis ZERO (skips PGK)

glucose+NADPH--(aldose reductase)-->sorbitol+NADP

diabetes/cataracts

hypoxia inducible transcription factor

stimulates growth of tumors by increasing the expression of signal molecules

G6P+NADP-->6-phosphogluconolactone+NADPH+H

6-phosphoglucolactonate+H2O-->6-phosphogluconate+H

6-phosphogluconate+NADP-->Ru5P+NADPH+CO2

beta-KA intermediate

3 Ru5P<-->1,2-endiol intermediate<-->1 Ribose5P

3 Ru5P<-->2,3-endiol intermediate<-->2 Xu5P

1. Xu5P+R5P<-->GAP+S7P
2. E4P+R5P<-->GAP+F6P

transfers 2-C units
**requires TPP

GAP+S7P<-->E4P+F6P

transfer 3-C units
lysine active site

Xu5P activates PP2A
PP2A dephosphorylates PFK2/FBPase2 (stimulating glycolysis)
increased glycolysis=high amts of A-CoA-->lipid synthesis

1. debranching enzyme
2. glycogen phosphorylase /PLP**(glycogen+Pi-->G1P)
3. phosphoglucomutase (G1P-->G6P)
4. G6Pase (G6P+H2O-->glucose+Pi)

glycogen+Pi-->G1P
**PLP
**key regulatory enzyme
active=OPO3
allosteric:
(+) AMP
(-) ATP, G6P, glucose
covalent:
(+) kinase (adds P/more active); glucagon
(-) phosphotase (removes P/less active)

1. phosphoglucomutase (G6P-->G1P)
2. UDP-glucose pyrophosphorylase (G1P+UTP-->UDP-glucose+Pi)
3. glycogen synthase (UDP-glucose+glycogen-->UDP+glycogen[n+1]
4. glycogenin
5. branching enzyme

UDP-glucose+glycogen-->glycogen[n+1]+PPi
active form=OH
allosteric:
(+) G6P, ATP
(-) AMP
covalent:
(+) phosphatase (removes P)
(-) kinase (adds P)

deficiency of G6Pase
accumulation of glycogen/inability to respond

deficiences of debranching enzyme; glycogen with short outer branches
high protein diets and frequent meals

deficiencies of branching enzyme; long unbranched chains with reduced solubility

very severe

glycogen brancing enzyme deficiency

found in some quarter horses
always fatal w/i 2-4 months

polysaccharide storage myopathy

excessive storage of glycogen

insulin hypersensitivity=too much glucose into muscle cells

involves GLUT4

-secreted by pancreas
-initiates DEPHOSPHORYLATION cascade (glycogen synthase)
(-)liver gluconeogenesis

"fight or flight" hormone
-secreted from adrenal glands
-initiates PHOSPHORYLATION cascade (glycogen phosphorylase)
-rapidly mobilizes short large amts of E
-LIVER AND MUSCLES

secreted by pancreas
maintains steady-state BG levels
initiates PHOSPHORYLATION (glycogen phosphorylase)
(+) gluconeogenesis
-LIVER ONLY

1. epi/glucagon stimulate cAMP production
2. cAMP activates cAMP-dependent protein kinase (PKA)
3. PKA phosphorylates phosphorylase kinase
4. phos. kinase phosphorylates gly. phos B to glyc. phos A

1. insulin stimulates series of reactions
2. phosphoprotein phosphatase 1 (PP1) dephosphorylates everything

ATP-->cAMP+PPi

cAMP+H2O--(phosphodiesterase)--> AMP

activated by binding of cAMP

PHOSPHORYLATION

inactivates glycogen synthase
activates phosphorylase kinase (which act. glycogen phosphorylase)

A-->B
(+)PKA
(+)Ca2+

only glyc phosphorylase B
allosteric:
(+)AMP
(-) ATP/G6P