sphinogomyelin

impt membrane component esp. in nervous sytem

synthesized from 2 routes by ceramide

ceramide

immediate precursor of sphinogolipids

second messenger for NGF

globoside

neutral cerebroside oligosaccharides

gangliosides

acidic ceramide oligosaccharides that contain N-acetyl neuraminic acid (NANA or sialic acid)

How is ceramide formed?

Sphingosine + acyl CoA → Ceramide + CoASH

                                       (Acyl CoA transferase)

ceramide + CDP-choline → sphingomyelin + CMP

OR

ceramide + phosphatidyl choline → sphingomyelin + DAG

cerebrosides

sulfatides

globosides

gangliosides

3’-phosphoadenosine-5’-phosphosulfate

It is an activated sulfate which converts galactocerebroside to sulfatide

Incoming base paring is selected by complementary base pairing with a template strand.

Chain growth is in the 5’ to 3’ direction

All DNA polymerases require a primer strand to add bases to.

prokaryotic DNA elongation and repair

5'-3' polymerization activity (synthesis)

5'-3' exonuclease activity (repair and removal)

3'-5' activity (proofreading)

prokaryotic DNA elongation and repair enzyme

complex structure; 10 subunits

forms a sliding clamp on the DNA strand

has a higher processivity than DNA polymerase I

enzyme that changes the topography of DNA molecules by cutting strands; allows the amount of supercoiling to be adjusted and re-ligating the strands

relieves supercoiling

leading strand - DNA continuously synthesized in 5'-3' direction

lagging strand - DNA discontinuously synthesized in 3'-5' direction (Okazaki fragments)

pieces of DNA that are replicated on the 3’-5’ (lagging) strand that will eventually be joined by ligases to make a complete DNA replicate strand.

initiated at oriC

terminated at the tau or ter site

DNA polymerase I has a low processivity (20 bases before it disassociates)

DNA polymerase III has a high processivity (5 million bases before it dissociates)

Eukaryotic DNA is much longer, the synthesis is much slower and occurs in accordance with the cell cycle.

Eukaryotic cells use a large number of DNA polymerase molecules and begin replication at multiple sites.

leading strand synthesis - DNA polymerase delta

lagging strand synthesis - DNA polymerase alpha

nucleosomes contain positively charged histone proteins

these + charged histones are attracted to the - charged  phosphate groups of DNA

Proliferating cell Nuclear Antigen (PCNA) is a cyclin that forms a clamp around the template DNA strand to dramatically increase the processivity of DNA polymerase delta.

Nucleosomes are cooperatively distributed after DNA replication

The new histones end up along one daughter stand near each replication fork

The histones from the original nucleosomes are found in the nucleosomes reformed along the other new strand

The presence of these histones (specifically the original ones, that remain associated with one strand of the replication fork) (may be why DNA polymerization is so much slower in eukaryotes)

anabolic - purine and pyrimidine de novo synthesis and salvage pathways

catabolic - purine and pyrimidine degradation pathways

purines - the ring is built as the pathway progresses.

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pyrimidines, the ring is built 1^st, then added to the PRPP.

MICROGLIA

fight infections; release inflammatory substances that could damage neurons

ASTROCYTES

regulate molecules necessary for inter-neuron communication

clear glutamate in the synapse to stop the neurotransmission mediated by glutamate

release neural growth factors

take up monoamine transmitters like serotonin or dopamine

OLIGODENDROCYTES

provide fatty myelin sheaths that insulate axons in the CNS

multiple sclerosis results when axonal connections die off

different amino acids (both ketogenic and glucogenic) synthesize different components of the TCA cycle.

For example, both aspartate and asparagine synthesize oxaloacetate

SEE PG. 71 IN DR. VENK'S LECTURE #1

(1) pyruvate→lactate (LDH M)

(2) lactate→pyruvate (LDH L)

Prolonged muscle activity results in pyruvate being converted into lactate by LDH M

lactate then moves from the muscle into blood and enters the liver

In the liver, LDH L converts lactate back into pyruvate

pyruvate is further metabolized to form glucose to gluconeogenesis

This entire process is known as Cori's cycle.

accumulation of lactate in the blood leads to lactate acidosis

indicative of tissue hypoxia, hypoperfusion, and possible damage

(1) tyrosine→DOPA (tyrosine hydroxylase)

(2) DOPA→dopamine (DOPA decarboxylase)

(3) dopamine→norepinephrine (hydroxylase)

(4) norepinephrine→epinephrine

(methyl transferase)

Rate limiting step = tyrosine hydroxylase catalyzed reaction (step 1)

Step 1 requires molecular oxygen and tetrahydrobiopterin (THB)

GABA is found in high concentrations in the brain where it serves as an inhibitory neurotransmitter.

glutamate→GABA (glutamate decarboxylase)

The enzyme requires the vitamin B6 derivate pyridoxal phosphate as a coenzyme so deficieny of vitamin B6 would impair activity of the decarboxylase and production of GABA.

Synthesis of Serotonin

1) Tryptophan→5-hydroxy tryptophan

(tryptophan hydroxylase)

2) 5-hydroxy tryptophan→serotonin

(decarboxylase)

Synthesis of Melatonin

1) serotonin→N-acetyl serotonin

(NAT)

2) N-acetyl serotonin→melatonin

(methyl transferase)

histidine→histamine

(histidine decarboxylase)

Functions: 1) mediate allergic and inflammatory reactions

2) powerful vasodilator

3) causes constriction of bronchioles in lungs

4) stimulates secretion of HCl in stomach

Synthesis

1) arginine + glycine→guanido acetate + ornithine

(transamidase)

2) guanidino acetate→creatine

(SAM-dependent methylation)

3) creatine→creatine phosphate

(creatine kinase)

Degradation

1) phosphocreatine→creatinine

(non-enzymatic conversion)

creatinine is excreted through the urine

pyridoxal phosphate

derived from vitamin B6

Endothelium-derived NO

NO diffuses out of endothelial cells and into vascular smooth muscle cells.

Activates cytosolic guanylate cyclase→increases cGMP

Activation of cGMP dependent protein kinase→phosphorylation of smooth muscle contractile proteins and relaxation

Brain-derived NO

receptors for NO in neurons

stimulation of guanylate cyclase→increased cGMP synthesis

Proteins that are phosphorylated and activated not well understood

Macrophage-derived NO

due to infections by bacteria, NO synthesis stimulated

NO toxic to bacteria

degeneration of the substantia nigra leads to reduced dopamine production

treated by: administration of L-DOPA which is precursor of dopamine that can cross blood brain barrier

Serotonin from synaptic cleft is taken up by presynaptic cells for catabolism

Treated with: Prozac which inhibits the serotonin reuptake process and enables prolonged serotonin presence in synaptic cleft

tumors of chromaffin tissue that produce large amounts of catecholamines

leads to hypertension

biopharmaceutical - drug produced in living cells

recombinant DNA - taking a given DNA sequence and putting it together in a different arrangment

cutting - use restriction enzymes

hybridizing - complementary base pairing of strands in test tube; GC and AT pairs (H bonds)

ligation - covalent bonds btwn base in each strand; ligases make covalent bonds; permanently put DNA strand back together; make sequence functional

small DNA circle in bacteria that can be cut with restriction enzymes and recombinant DNA can be replicated by ligating the recombinant sequence into the bacterial chromosome and allowing the bacteria to produce many copies of the DNA sequence

gene on a plasmid that is naturally occurring - Bacillacis anthracis toxins in DNA

not 1 polypeptide chain but 2 (A and B chains)

3 disulfide linkages and bacteria don't have disulfide linkages

bacteria produces more product than yeast

bacteria easier to set up and maintain than yeast

insulin is already folded and disulfide bonds are linked correctly

more like mammalian cells

block TNF alpha signal transduction pathway

fusion protein b/c it binds to the TNF alpha receptor with a receptor domain and a immunogammaglobulin to pull TNF alpha away from cell and float in circulation (decoy)

it can take a lot of time in the lab to grow small molecule drugs and see what blocks signal transduction pathway

This small molecule conventional drug might have a more specific effect???

folding is more like a human than yeast

additions of sugars and other modifications are required for some proteins that can be done by the hamster ovary cells

recombinant DNA molecule based on moloclonal antibody sequence information b/c eliminate human immune response to mouse antibody

humanized antibody - monoclonal antibody exposed to  humans and those humans who don't have an immune response have their DNA substituted for the mouse DNA to prevent an immune reaction