M2 L3 Flashcards
FIBROUS PROTEINS
3
COLLAGEN
ELASTIN
KERATIN
GLOBULAR PROTEINS
2
MYOGLOBIN
HEMOGLOBIN
- Triple helix
- Has 3.3 residues per turn and a rise per residue nearly twice that of an α-helix
- Every 3rd amino acid residue is a glycine residue
- Gly-Pro-X or Gly-Hyp-X
COLLAGEN
COLLAGEN
Every 3rd amino acid residue is a
GLYCINE RESIDUE
sequence of collagen structure
Gly-Pro-X
x could be any rare amino acid (could be hydroxyproline or hydroxylysine)
COLLAGEN STRUCTURE
what do we need in order for us to achieve the hydroxylated form of proline & lysine
ASCORBIC ACID IN THE FORM OF ASCORBATE
saan nakukuha ang ascorbate
in our diet
Vit C supplement
in the biosynthesis of collagen, we need to have the chain of ____
PRE-PROCOLLAGEN ON RIBOSOMES
synonym of protein synthesis
TRANSLATION
BIOSYNTHESIS OF COLLAGEN
the ____ directs the pre-procollagen to the RER
SIGNAL PROTEIN
BIOSYNTHESIS OF COLLAGEN
removing a certain portion
removal of registration peptides
CLEAVAGE
BIOSNTHESIS OF COLLAGEN
cleavage of signal protein forms ____
PROCOLLAGEN
process of biosynthesis of collagen
in order
- chain of pre-procollagen, directed to RER by signal proteins
- formation of cleavage of signal protein = forms collagen
- hydroxylation of lysine & proline
enzymes in biosynthesis of collagen
PEPTIDYL LYSINE HYDROXYLASE
PEPTIDYL PROLINE HYDROXYLASE
addition of OH- group
HYDROXYLATION
BIOSYNTHESIS OF COLLAGEN
attachment of sugar to some hydroxylysine residues
GLYCOSYLATION
BIOSYNTHESIS OF COLLAGEN (GLYCOSYLATION)
Addition of ____ and ____ to some
hydroxylysine residues.
GALACTOSE
GLUCOSE
BIOSYNTHESIS OF COLLAGEN
enzymes required for glycosylation
GALACTOSYL TRANSFERASE
GLYCOSYL TRANSFERASE
involves transfer of groups
TRANSFERASE
BIOSYNTHESIS OF COLLAGEN
how many α-chains of procollagen are needed to have self association
3
BIOSYNTHESIS OF COLLAGEN
what is needed to have stability of procollagen
DISULFIDE BONDS
BIOSYNTHESIS OF COLLAGEN
formation of disulfide bonds is called
REGISTRATION PEPTIDES
BIOSYNTHESIS OF COLLAGEN
involves the formation of disulfide bonds between parts of the polypeptide chains
ASSEMBLY OF THREE α-CHAINS TO FORM PROCOLLAGEN
BIOSYNTHESIS OF COLLAGEN
formation of disulfide bonds between parts of the polypeptide chains known as ____ which occur at both ends of the pre-procollagen.
REGISTRATION PEPTIDES
BIOSYNTHESIS OF COLLAGEN
registration peptides are found at the
ends of pre-procollagen
BIOSYNTHESIS OF COLLAGEN
The assembly process of 3 α-chains occurs in the
GOLGI APPARATUS
BIOSYNTHESIS OF COLLAGEN
Secretion of procollagen molecules by ____ into the extra cellular space
EXOCYTOSIS
BIOSYNTHEIS OF COLLAGEN
- Occurs in the extra cellular space, and is catalyzed by procollagen peptidases.
- The resulting molecule is called tropocollagen.
CLEAVAGE OF REGISTRATION PEPTIDES
BIOSYNTHESIS OF COLLAGEN
the resulting molecule in the cleavage of registration peptides
TROPOCOLLAGEN
BIOSYNTHESIS OF COLLAGEN
cleavage of registration peptides occurs in the
EXTRACELLULAR SPACE
BIOSYNTHESIS OF COLLAGEN
cleavage of registration peptides is catalyzed by
PROCOLLAGEN PEPTIDASES
BIOSYNTHESIS OF COLLAGEN
Self-assembly or polymerization of tropocollagen molecules form
COLLAGEN FIBRILS
BIOSYNTHESIS OF COLLAGEN
____ between adjacent tropocollagen molecules stabilizes the fibrils.
CROSS-LINKAGE
BIOSYNTHESIS OF COLLAGEN
Self-assembly or polymerization of tropocollagen molecules involves the ____ which has a net oxidative effect and the formation of covalent cross-links.
REMOVAL OF AN AMINO GROUP
BIOSYNTHESIS OF COLLAGEN
Self-assembly or polymerization of tropocollagen molecules is catalyzed by
LYSINE OXIDASE / CATALASE
- like a glue
- holds our joint together
COLLAGEN
- Inheritable defects in collagen molecule;
- Characterized by stretchy skin and loose joints;
- Due to defect in genes that encode α- collagen-1, procollagen N-peptidase, or lysyl hydroxylase.
EHLERS-DANLOS SYNDROME
a person suffering from this disease has a flexible body structure
EHLERS-DANLOS SYNDROME
deficiency in α- collagen-1, procollagen N-peptidase, or lysyl hydroxylase
EHLERS-DANLOS SYNDROME
- severe form of ehlers-danlos syndrome
- prone in falling; possibility to have bone breakages
VASCULAR TYPE
- Brittle bone syndrome
- Bones easily bend and fracture
- stunted growth
- irregular bone structures
- permanent disability
OSTEOGENESIS IMPERFECTA
osteogenesis imperfecta is also known as
brittle bone syndrome
- Characterized by kinky hair and growth retardation
- Due to dietary deficiency of copper required by lysyl oxidase, which catalyzes a key step in the formation of the covalent cross-links that strengthen collagen fibers.
- a genetic disorder caused by a mutation usually primarily in the Y Chromosome (boys) it affects the copper levels and metabolism in the body causing seizures, brain damage, weakened bones and muscles, organ shutdown and failure to thrive.
MENKE’S SYNDROME
KINKY HAIR SYNDROME
Menke’s syndrome is otherwise known as
KINKY HAIR SYNDROME
common affected by the menke’s syndrome / kinky hair syndrome
MALE / BOYS
- Best known defect in collagen biosynthesis;
- Deficiency of Vit. C (required by prolyl and lysyl hydroxylases);
- Bleeding gums, swelling joints, poor wound healing, and ultimately death.
SCURVY
required by proline & lysyl hydroxylases
VIT C
ASCORBIC ACID
- Connective tissue protein with rubber-like properties
- Found in lungs, walls of large blood vessels, and elastic ligaments
- Can be stretched to several time their normal length, but recoil to their original shape when relaxed.
ELASTIN
- responsible for lung’s elastic property
- its ability to inflate & deflate
ELASTIN
- Composed primarily of small non polar amino acid residues (e.g. G, A, V).
- Also rich in proline and lysine, but contains little hydroxyproline and hydroxylysine.
- Interchain cross-links form desmosine residues.
ELASTIN
interchain cross-links of elastin form
DESMOSINE RESIDUES
An extensively interconnected, rubbery network that can stretch and bend in any direction when stressed, giving connective tissue elasticity.
DESMOSINE CROSS-LINK
one of the leading case of non communicable diseases accdng to the DOH
EPHYSEMA
- does not have repair mechanism
- cannot deactivate neutrophil elastases
EMPHYSEMA
reactive oxygen species (ROS) are also known as
FREE RADICALS
stimulates pro-inflammatory mediators such as IL-8, LTB, TNF
NICOTINE
Inhibit neutrophil elastase (protease that degrades elastin of alveolar walls)
α-1 antitrypsin
Deficiency of α-1 antitrypsin leads to destruction of the alveolar walls of the lungs resulting to
EMPHYSEMA
treatment for emphysema
administration of α-1 AT
- the lungs natural defense against the irritants
- attach themselves to the foreign material in the sac and consumes it as well as bacteria in the lungs
ELASTASE
Once the lungs has been cleaned,
____ deactivates elastase.
ANTITRYPSIN
Without the antitrypsin enzyme, the ____ continues to consume anything in its path, including healthy lung tissue.
ELASTASE
- Proteins that forms tough fibers;
- Found in the hair, nails, and outer epidermal layers of mammals;
- Constituents of intermediate filaments of cytoskeleton in certain cells.
α-KERATIN
why hair and nails are insoluble in water
non polar R groups are found outside which makes it insoluble in water
- Group of specialized protein that contains heme.
- Maintain a supply of oxygen essential for oxidative metabolism
– MYOGLOBIN
– HEMOGLOBIN
GLOBULAR HEMEPROTEINS
- Fe+2- protoporphyrin IX
- A cyclic tetrapyrrole
- protein that are produced by amino acids
- A planar network of conjugate double bonds absorbs visible light and colors heme deep RED.
HEME
amino acids that are not directly involved in protein synthesis
NON PROTEINOGENIC
- A monomeric protein (153 amino acid residues) of the red muscles
- Used in some tissues, notably muscle,
– as a storage reserve of O2
and
– for intracellular transport of O2
MYOGLOBIN (Mb)
predominant secondary structure that is visible in the tructure of myoglobin
α-helix
myo means
muscles
- 78% α helical (the other 22% in β turns and short loops, no β sheet at all)
- 8 α - helices and connections between helices are referred to as “AB”, “CD”, etc.
- Polar amino acid residues are found at the surface
- Non polar amino acid residues (L, V, F, & M) are found at the interior except His E7 and HisF8
MYOGLOBIN
The heme of myoglobin lies in crevices of
HELICES E & F
SUBUNIT COMPOSITION
Fetal hemoglobin (HbF)
α2γ2
major hemoglobin in adults
HEMOGLOBIN A (HgA)
SUBUNIT COMPOSITION
Hemoglobin A
α2β2
SUBUNIT COMPOSITION
sickle cell hemoglobin (HbS)
α2S2
SUBUNIT COMPOSITION
minor adult hemoglobin (HbA2)
α2δ2
have almost identical secondary and tertiary structures
Myoglobin and the β polypeptide of hemoglobin
composed of two identical
dimers, (αβ)1 and (αβ)2, dimers 1 and 2
respectively
Hgb tetramer
Dimers are held together by
HYDROPHOBIC INTERACTIONS
also occur between the members of the dimer
IONIC & H-BONDING
- Deoxy form of Hgb
- Two αβ dimers interact through a network of ionic bonds and hydrogen bonds
T FORM OR TAUT (TENSE) FORM
Low oxygen-affinity form of hemoglobin
T FORM OR TAUT (TENSE) FORM
- Binding of oxygen to Hgb (oxyhemoglobin)
- Some ionic bonds and H-bonds between the αβ dimers are ruptured thus, the polypeptide chains have more freedom of movement
R FORM OR RELAXED FORM
High oxygen-affinity form of hemoglobin
R FORM OR RELAXED FORM
Hemoglobin binding sites per molecule
4 O₂
____ cooperate in binding oxygen
SUBUNITS
The oxygen dissociation curve for Hemoglobin is ____ in shape
SIGMOIDAL
Can bind only one molecule of oxygen (one heme group only)
MYOGLOBIN
The oxygen dissociation
curve for Myoglobin is a ____ shape
HYPERBOLIC
reversibly binds a single molecule of oxygen
MYOGLOBIN
- It means that the binding of an oxygen molecule at one heme group increases the oxygen affinity of the remaining heme group in the same Hgb molecule
- This is referred to as heme-heme
interaction
COOPERATIVE BINDING OF OXYGEN
cooperative binding of oxygen is also referred to as
HEME-HEME INTERACTION
cooperative interactions are also called
ALLOSTERIC INTERACTIONS
allos
OTHER
STEREOS
SPACE
a ligand that influences other ligand to bind at a specific site
ALLOSTERIC EFFECTOR / MODULATOR
occur when binding of one ligand at a specific site is influenced by binding of another ligand
ALLOSTERIC INTERACTIONS
second site in allosteric interactions
ALLOSTERIC SITE
the interacting sites all bind the same ligand (e.g., binding of O2 at one site on Hb influences the binding affinity for O2 of another site)
HOMOTROPIC INTERACTION/EFFECT
the interacting sites bind different ligands
HETEROTROPIC INTERACTION/EFFECT
- Positive effect
- the effector increases the binding affinity for the same kind of ligand at other sites
- O2 in the hemoglobin system increases the O2 binding affinity of other sites
HOMOTROPIC INTERACTION / EFFECT
increases the binding affinity for the same kind of ligand at other sites
HOMOTROPIC EFFECTOR
- the effector decreases the binding affinity for the primary ligand
- protons, or CO2, or 2,3-BPG
NEGATIVE HETEROTROPIC EFFECTOR / ALLOSTERIC INHIBITOR
effector increases the binding affinity for the primary ligand
POSITIVE HETEROTROPIC EFFECTOR / ALLOSTERIC ACTIVATOR
effect of binding of protons (H+) and CO₂ on O₂ binding affinity of Hb
HbO₂ + H+ ↔ HbH+ + O₂
BOHR EFFECT
Increase protons or a lower pO₂
Deoxyhemoglobin
Decrease protons or an increase pO₂
Oxyhemoglobin
has darker color
oxyhemog or deoxyhemog
OXYHEMOGLOBIN
CO₂ is a ____ of O₂ binding to Hb
NEGATIVE HETEROTROPIC EFFECTOR / ALLOSTERIC INHIBITOR
CO binds ____ (but ____) to the Hb iron, forming carbon monoxyhemoglobin, HbCO
TIGHTLY, REVERSIBLY
CO binding to one or more of the 4 heme sites of Hb shifts to
RELAXED CONFORMATION
The affinity of Hb for CO is ____ greater than for oxygen
220x
% of HbCO are fatal
60%
CO poisoning is treated with ____, which facilitates the dissociation of CO.
OXYGEN THERAPY
CO %
mild poisoning
0,08%
CO
moderate posioning
up to 0,32%
CO
severe poisoning
above 1,2%
- Most abundant organic phosphate in the red blood cells
- Binds strongly to the deoxy form of Hb (T state), but only very weakly to oxy form (R state)
- Favors/stabilizes the T form, reducing the O2 binding affinity of Hb (shifts binding curve to the right);
- Increased concentration of 2,3-BPG, reduce affinity of hemoglobin for O2 which increases the efficiency of O2 delivery (enhances RELEASE) to tissues
2,3-bisphosphoglycerate (2,3-BPG) or “2,3-diphosphoglycerate” (DPG)
Increase concentration of 2,3-BPG is observed in:
*Chronic hypoxia
*High altitudes
*Chronic anemia
- The heme iron is ferric than ferrous
- Oxidation of ferrous to ferric is caused by the side effects of drugs such as sulfonamides, or endogenous substance like hydrogen peroxide
- Can neither bind nor transport oxygen
METHEMOGLOBIN
HisF8 has been replaced by tyrosine
HEMOGLOBIN M
V has replaced Glu6 of the β-subunit
HEMOGLOBIN S
Dark red coloration of urine following massive crush injury because myoglobin is released from damaged muscle fibers
MYOGLOBINURIA
Reduction in the number of RBC or of Hb in the blood, or impaired production of erythrocytes (Vit.B12 deficiency)
ANEMIA
Partial or total absence of one or more α (α-thalassemia) or β (β-thalassemia) chains of hemoglobin
THALASSEMIA
- Glucose enters the erythrocytes and glycosylates the α-group of lysine residues and the amino terminal of Hb
- Reflects the mean blood glucose concentration thus provides valuable information for management of Diabetes Mellitus
GLYCATED HEMOGLOBIN (HbA₁c)
to know if the patient is resistant to OHAS, the HbA₁c should be around
5.7-6.4