Patient is clinically dehydrated with low BP. Respirations are deep and rapid, pulse rate is rapid. Breath has a "fruity" odor of acetone. Blood pH is 7.08 (low). Ketone bodies are present in the urine - ketoacidosis (fatty acids are metabolized to ketone bodies).

Blood glucose is high. Polyuria from osmotic diuresis. Coma.

Respiratory alkalosis first, cuased by direct stimulation of the respiratory contorl center (increasing rate of breathing).

Followed by a complex metaboolic acidosis because of dissociatoin of salicylic acid. Interferes with ATP production, increases CO2 and accumulation of lactate and other organic acids in the blood.

Asparagine (asn), Glutamine (gln), Serine (ser), Threonine (thr)

Participate in H-bond interactions with water, eachother or with protein backbone

Found at the surface of water soluble proteins

Cysteine (cys) - participates in disulfide bridges 

Selenocysteine (sec) - found in proteins with antioxidant activity.

Through van der Waals forces form:

Hydrophobic cores of proteins, shielded from the aquueous environment)

Membrane spanning domain of membrane proteins (membrane lipids have large hydrophobic tails)

Hereditary pancreatitis is a disease caused by the premature activation of trypsin in the pancreas. Which of the following amino acids is most likely present in this enzyme’s catalytic site that interacts with and cleaves the peptide bond of proteins?

Serine.

Peptide bonds are polar, a polar amino acid will interfere.

Note: Trypsin protease contains a serine.

Normal: Glu6 (negative charge)

Sickle Cell Anemia: Val6 (neutral charge)

Hemoglobin C: Lys 6 (positive charge)

On a gel electrophoresis, going from cathode (-) to anode (+): normal goes furthest, then sickle cell, then HbC travels the lesat distance.

Glu6 --> Val6

HbS polymerizes in RBCs and deforms them (sickle shape).

Inflexible RBC's block capillaries leading to insufficient delivery of oxygen to tissues (anoxia) and severe pain (crises).

Lifetime is much shorter than normal RBC (20 vs. 120 days), which leads to hemolytic anemia.

Diactylitis (pain and swelling in hands and feet)

Splenomegaly.

Increased incidence of infections (due to dysfunctional spleen).

HbA (normal): alpha2beta2

HbF (fetal): alpha2gamma2

HbA2: alpha2delta2

HbA1c: alpha2beta2-glucose (diabetics)

Ck consists of 2 subunits.

There are 3 isoforms (isoenzyme)

BB: in brain (CK-1)

MB: in heart mmuscle (CK-2)

MM: in skeletal muscle (CK-3)

Normal MB: < 5%

Infarction MB: > 5%

Timeline:

MB detected after 4-8 hrs

MB peaks: 12-24 hrs

MB returns to normal: 48-72 hrs

Increases the solubility of a protein.

Ex: extracellular and cell membrane proteins

Ex: hemoglobin glycosylated by blood glucose (proportional to blood glucose level). Used to monitor diabetic patients (HbA1c levels).

Phosphorylation - change enzyme activity

Acetylation - can change histone-DNA interactions and alter gene transcriptoin

ADP-ribosylation - can alter intracellular signaling or protein synthesis (pathogenic bacteria use this to modify host cells: cholera, pertussis, diptheria)

Which amino acid is most likely found in the membrane-

spanning domain of a transmembrane protein?

Leucine

*Or any hydrophobic amino acid

Precipitation of various misfolded proteins in different tissues/organs.

Protein precipitation causes organ failure.

Wide variety of diseases dpending on the prtoein involved.

Precipitated proteins has similar beta sheet rich structure.

AL Amyloidosis: Precipitation of antibody light chains, frequent in multiple myeloma.

Alzheimners disease: precipitation of beta-amyloid protein, leading to brain degeneration

Associated with abnromal denaturation of the prion protein in the brain.

Note the excessive beta sheets!!

Infectious form: Mad Cow Disease (through infection)

Genetic form: Creutzfeldt-Jacob disease (due to mutation)

 Beta Sheets

*Present with precipitation  of proteins

Myoglobin oxygen saturation curve is hyperbolic (no cooperativity)

Hemoglobin oxygen saturation curve is sigmoid (there is cooperativity)

In muscle capillaries when O2 pressure is low, O2 binds myoglobin more strongly than hemoglobin

Shifts the oxygen dissociation curve to the right (makes it easier to release oxygen to tissues)

In hypoxemia (ex: high altitudes) the 2,3-BPG levels increase to facilitate unloading of oxygen in the tissues (shifts further right)

1. High CO2 concentration leads to increased proton concentration and lower pH. Most is converted to bicarbonate + H+.

High H+ (low pH) stimulates oxygen dissociation.

2. Direct binding of Co2 to Hb stabilizes the deoxy form, allowing oxygen unloading. It does this because CO2 does not bind heme, but forms a carbamate with amino terminal amino groups.

CO binds more tightly to heme than Oxygen. Forms carboxyhemoglobin.

Leads to tissue hypoxia.

Shifts saturation curve left.

Has a higher O2 affinity than HbA because it has a lower affinity to 2,3-BPG.

Curve is shifted left.

Myoglobin

*Result of strenuous exercise (muscle breakdown) and no red blood cells (no hemolytic anemia - NOT HEMOGLOBIN)

Note: Myoglobin saturation curve is shifted furthest to the left

Acquired: excessive oxidation of drugs or nitrates

Hereditary: mutation in NADH-cytochrome b5 reductase (or certain mutation in Hb that prevents the reduction of Fe+3)

Hb is bound to Fe+3 rather than Fe+2.

Symptoms: chocolate colored blood, bluish skin and mucous membranes (cyanosis), shortness of breath, headache and seizure.

Decreased amounts or absence of alpha-chain Hb.

Leads to HbH (all beta), Hb Barts (all gamma) and beta chain precipitate.

Oxygen will not be released to the tissues due to tight binidng of the gamma and beta homotetramers.

Decreased amounts or absence of beta-chain.

Increased fetal hemoglobin (alpha2gamma2)

Also, alpha chain precipitate.

2 forms:

beta 0 - complete lack of beta chains

beta+ - greatly reduced levels of beta chains

Decreased production of hemoglobin alpha chains

*Presence of beta homotetramers and gamma homotetramers indicates that there is a decreased production of alpha chains

*Alpha thalessemia

1. mRNA is synthesized from DNA in nucleus. Is translated and synthesized into procollagen chains in the rough endoplasmic reticulum (RER).
2. Still in RER, proline and lysine residues are hydroxylated into hydroxyproline and hydroxylysine

3. Glycosylation of hydroxylysine residues takes place.

4. Still in the RER, the triple helix is assembled.

5. Proceeds from carboxy terminal end to amino terminal end. Process is initiated by disulfide bonds within the chains. Then triple helical formation will proceed further

6. Triple helix held together by hydrogen bonds

7. Hydroxyproline plays a steric role in stabilizing this triple helix structure.
   8. Once triple helix is assembled, it is released from cell via exocytosis.
   9. Once in ECM, the propeptides are cleaved off by enzymes called N and C procollagen peptidases.
   10. Final triple helical molecule is produced and will be assembled into collagen fibrils.

during the synthesis of collagen chains in the endoplasmic reticulum.

*Post translational modifications occur in RER and are done before assembly of collagen helix.

Produces hydroxyproline.

Requires Fe+2 and Vitamin C (ascorbate) as cofactors

Stabilizes triple helix of collagen

Produces hydroxylysine, which participates in crosslinking of collagen chains.

Requires Fe+2 and vitamin C (ascorbate) as cofactors

Oxidizes lysine and hydroxylysine to form covalent crosslinks within collagen fibers.

Requires Cu+2 as a cofactor.

Produces allysine (or hydroxyallysine) residue which will react with lysine/hydorylysine/allysine/hydroxyallysine residues to create covalent crosslinks between collagen chains.

Vitamin C deficiency.

Caused by lack of fruits and veggies in the diet

Prolyl and lysyl hydroylases do not function (require vitamin C)

Less stable collagen triple helix and crosslinking is reduced

General connective tissue disease.

Spots, bruises on skin (especially on legs)

Bleeding gums, loose teeth

Delayed wound healing

Classic type: Type V collagen mutation (fibril associated)

Causes hyperextensive skin, delayed wound healing, atrophic scars, joint hypermobility

Vascular type: Type III collagen mutation

Causes arterial, intestinal and uterine (during pregnancy) ruptures.

Kyphoscoliotic type: Lysyl Hydoxylase deficiency

causes hyperextensive skin, delayed owund healing, easy bruising, thin scars, joint hypermobility, progressive scoliosis

7 types

Types 1-4 are associated with Type I collagen mutations.

Symptoms: increased incidence of fractures, short stature, grey or brown teeth that wear down easily (dentinogenesis imperfecta), blue sclera

Mutations in Type IV collagen.

Affect glomerular basement membranes.

Symptoms: hematuria (RBCs in urine), proteinuria, renal insufficiency

Prolyl Hydroxylase or lysyl hydroxylase

*Requires Vitamin C as a cofactor

Inhibits neutrophil elastase in the lungs.

If deficient, leads to degradation of elastin in lungs which can collapse the small airways.

Exacerbated in smokers.

Fibrillin-1 mutation.

Microfibrils are deficient, so elastic fibers are deficient.

Symptoms

Skeletal: very tall stature, kyphoscoliosis, disproportionally long limbs, fingers and toes, hyperflexible joints

Ocular: Dislocation of the lens of the eye (ectopia lentis)

Cardiovascular: Dilation of the aorta, heart valve problems

Laminin and integrin deficiency/mutation.

Mainly affects the basement membrane below the epidermis and mucosal membranes.

Main symptom is fragile skinathat shows extreme blistering.

Composed of repeating disaccharide units of an acidic sugar (uronic or iduronic acid) and an N-acetylated amino sugar.

All but hyaluronic acid:

are attached to a protein core, are synthesized in in the golgi, are sulfated

The negative charges attract a lot of water, which makes them behave like sponges. Confer resilience to tissues under compressive forces.

Found in skin, blood vessels and heart valves.

Can lead to mitral valve prolapse if it over accumulates.

Only GAG that does not contain acidic sugar

Found in cornea and cartilage.

Deficiency can lead to macular corneal dystrophy (cloudy corenas, vision impairment)

Mucopolysaccharidoses I.

Alpha-L-iduronidase deficiency

Leads to early death.

Deficient lysosomal degradation of GAGs.

Essential for correct lysosomal targeting of macromolecules (GAGs, glycoproteins, glycolipids).

They require phosphorylation of mannose.

Deficient mannose phosphorylation on lysosomal enzymes. There are not delivered to the lysosomes. Macromolecules are not degraded, leading to enlarged lysosomes, inclusion bodies.

Result in skeletal abnormaltiies, restricted joint movement, coarse facial features, severe psychomotor impairment. Death by 8 years of age.

Autoimmune neuromuscular disease (muscle weakness/fatigue).

Autoantibodies against the nicotinic Ach receptors inhibit Ach binding to the receptor, enhance the internalization and destruction of the receptor. Low levels of functional Ach receptors on skeletal muscles.

Treatment: acetylcholine esterase inhibitors (reversible) --> elevate Ach levels --> more efficient signaling through fewer receptors

Certain insecticides, nerve gases (sarin, vx)

Leads to excess Ach

Contractoin relaxation cycle of muscle is impaired (dangerous in the heart)

Leads to death

Treatment: Ach receptor antagonists (blockers) inhibit Ach signalling.

Ex: Atropine, a muscarinic Ach receptor antagonist

Steroid hormones.

Bind in cytoplasm, move to nucleus

Type I - cortisol, aldosterone, progesterone, testosterone

Type III - estradiol

Ex: Dexamethasone (30 times more efficient than natural cotisol)

Bind directly in nucleus.

Thyroid hormone, vitamin D3, retinoic acid

Binds a receptor and a coactivator replaces a corepressor, leading to induction of gene transcription.

Transfers ADP-Ribose group to a stimulatory Gsalpha subunit.

Prevents hydroylxation of GTP to GDP so adenylyl cylcase remains constantly active. Leads to salt efflux from gut epithelial cells to the lumen (diarrhea).

Used by cytokines.

JAKs are tyrosine kinases.

STATs are signal tranducer proteins

Used by growth factors and insulin

Can activate MAP-kinase pathway, phospholipase C pathway, IP-3 kinase

Autoantibodies stimulate TSH receptors in the thyroid gland, increasing thyroid hormone production.

This downregulates TSH production but has no effect on autoantibodies.

Negative feedback does not work.

Vmax does not change.

Inhibition can be reversed by high [S]

Km is increased - more substrate is required to achieve 2/3 Vmax

Binds at a different site on the enzyme. Can also bind the enzyme-substrate complex.

Decreases Vmax. Km does not change.

Glucose 6 phosphatase deficiency.

Hepatomegaly, renomegaly. Growth retardation and delayed puberty.

Acid-alpha-glucosidase deficiency (lysosomal).

Cardiomegaly, general weak muscle tone.

Glycogen phosphorylase deficiency (skeletal muscle).

Cramping of skeletal muscle after exercise.

No increase in lactate after exercise. Increased myoglobin.

Temporary weakness after exercise.

A 32-year old male patient visits the urologist and complains about cramps and red discoloration in his urine after a very strenuous exercise. The patient does not have hemolytic anemia and there were no red blood cells in his urine. Non-ischemic lactate forearm test shows no increase in lactate after exercise. What enzyme is most likely deficient in this patient?

Thiamine pyrophosphate, lipoic acid, CoA, FAD and NAD+ (niacin)

Alpha ketoglutarate dehydrogenase requiers the same coenzymes

Forms complex with thiol (-SH_ group of lipoic acid in pyruvate and alpha-ketoglutarate dehydrogenases.

Results in accumulation of pyruvate and lactate.

Affects brain, causing neurological problems and death.