Quiz
Collagen and Elastin
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Fragen in diesem Quiz (7)
1 • Alpha Keratin: skin and hair
• [blank_start]Elastin[blank_end]: Tissue that undergoes stretching
• [blank_start]Proteoglycans[blank_end]: components of the extracellular matric
• Tubulin: muscle and most cells
• Adhesive Glycoproteins ([blank_start]fibronectin[blank_end] & [blank_start]laminin[blank_end]): form a mesh of fibers that bind cells and other molecules to components of the extracellular matrix
• Collagen Overview:
○ Primary structural protein in the body: most abundant in strong, tough connective tissues: tendons, cartilage, bones, cornea of the eye
○ The most prevalent protein - approx. 30% of ALL proteins
○ Approximately 28 distinct types identified: characterized by different [blank_start]alpha[blank_end] chains; each type found in particular locations of the body
○ Type 1, 2 and 3 are the abundant of the collagens with type1 being the most abundant protein in mammals
• Type [blank_start]1[blank_end]: skin, bone, tendon, blood vessels, cornea
• Type [blank_start]2[blank_end]: cartilage, vitreous body
Type [blank_start]3[blank_end]: blood vessels, skin, muscle- AProteoglycans
- BElastin
- Claminin
- Dfibronectin
- Ealpha
- F1
- G2
- H3
2 ○ Each single collagen chain is a long Gly and Pro rich [blank_start]left[blank_end] handed helix individually
• Proline and hydroxyproline confer rigidity
○ Three collagen chains intertwine into a [blank_start]right[blank_end]-handed super-helical [blank_start]triple[blank_end] helix ([blank_start]left[blank_end] handed Gly and Pro to form right handed)
○ [blank_start]Glycine[blank_end] occurs at every third position of the triple helical portion of the alpha chain
○ Triple helix made up of 3 polypeptide chain subunits ([blank_start]alpha[blank_end] chains)
○ The triple helix has higher tensile strength than a steel wire of equal cross section
○ Many triple-helices assemble into a collagen [blank_start]fibril[blank_end]
○ Gly- X- Y repeats; X is often a proline and usually [blank_start]hydroxyproline[blank_end]
○ Glycine is small enough to fit in the triple helix
• Glycine deficiency affects collagen structure because glycine holds the collagen structure with its [blank_start]hydrophobic[blank_end] bonds
○ Triple helix forms intra and inter disulfide bonds
• Formation of [blank_start]disulfide[blank_end] bonds and further enhance the stability of the folded conformation of a peptide
○ [blank_start]Intrapolypeptide[blank_end] disulfide bonds involves oxidation of the cysteinal sulfhydryl groups and requires oxygen
[blank_start]Interpolypetide[blank_end] disulfide bonds stabilize the quaternary structure of certain oligomeric proteins- Aleft
- Bleft
- Cright
- Dtriple
- Ealpha
- FGlycine
- Ghydroxyproline
- Hfibril
- Ihydrophobic
- Jdisulfide
- KIntrapolypeptide
- LInterpolypetide
3 • Post-Translational Modifications of Polypeptide Chains - hydroxylation reactions
○ [blank_start]Hydroxylation[blank_end] of Proline and lysine residues in collagen. Proline and lysine within chains are hydroxylated by reactions that require molecular oxygen , iron (Fe+) and the reducing agent vitamin C and [blank_start]cofactors[blank_end] (ascorbate, ascorbic acid), Fe+ is required to [blank_start]activate[blank_end] oxygen
• Hydroxyproline is formed by posttranslational hydroxylation of peptide-bound proline residues catalyzed by [blank_start]prolyl hydroxylase[blank_end]
• Hydroxylation forms H-bonds for inter and intra strands (stabilize the triple helix) formed between glycine and other AA
• Defective hydroxylation can cause devastating effects due H-bonds and [blank_start]disaccharides[blank_end] won't be able to me made
• Hydroxyproline and [blank_start]succinate[blank_end] complete the hydroxylation reaction
○ Hydroxylysine
• [blank_start]Lysine[blank_end] and alpha [blank_start]ketoglutarate[blank_end] start this reaction
• The cofactors here are oxygen, iron and [blank_start]ascorbate[blank_end] as well
• Hydroxylysine and [blank_start]succinate[blank_end] are the final products that complete the reaction
• Hydroxylysine are sites of attachment of disaccharide groups
Some hydroxylysines can be further modified by addition of [blank_start]galactose[blank_end] and galactosyl-glucose through an O-[blank_start]glycosidic[blank_end] linkage, a [blank_start]glycosylation[blank_end] site that is unique to collagen- Acofactors
- BHydroxylation
- Cactivate
- Dprolyl hydroxylase
- Edisaccharides
- Fsuccinate
- Gketoglutarate
- HLysine
- Iascorbate
- Jsuccinate
- Kglycosidic
- Lglycosylation
- Mgalactose
4 • Collagen forms Long [blank_start]Rod[blank_end]-Like Structures
○ These are fibers in tissues
○ Assembled into [blank_start]lateral[blank_end] association of triple helical units called fibrils, which in turn into fibrils and then into thicker fibers
○ Collagen is further stabilized by covalent [blank_start]cross-links[blank_end] that form [blank_start]lysyl oxidase[blank_end] (copper dependent) that [blank_start]deaminates[blank_end] the epsilion amino groups of certain lysine and hydroxylysine residues yielding reactive aldehydes
Aldehydes can form [blank_start]aldol[blank_end] condensation products with lysine or [blank_start]hydroxylysine[blank_end] to form [blank_start]Schiff bases[blank_end]- ARod
- Bcross-links
- Clysyl oxidase
- Ddeaminates
- Ehydroxylysine
- Faldol
- GSchiff bases
- Hlateral
5 • Lathyrism
○ Lathyrism is a paralyzing [blank_start]dietary[blank_end] disease that arises from regular consumption of seeds of Lathyrus odoratus, the sweet pea.
○ The seeds contain ß-aminoproprionitrile which inactivates [blank_start]lysyl oxidase[blank_end] - results in [blank_start]decreased[blank_end] crosslinking of collagen. Without these crosslinks, collagen is extremely fragile.
• Penicillamine is another collagen cross-linking inhibitor used in chelation therapy. It also causes lathyrism because it chelates copper ions that are needed for [blank_start]lysyl oxidase[blank_end] activity.
Penicillamine is used in the treatment of Wilson’s disease which is a copper overload disease.- Adietary
- Blysyl oxidase
- Cdecreased
- Dlysyl oxidase
6 • Elastin
○ Connective tissue protein responsible for properties of extensibility and elastic recoil
○ Major protein found in elastic tissues
○ Variants arise by alternative [blank_start]splicing[blank_end]
○ Once cross-linked in extracellular form, elastin is highly [blank_start]insoluble[blank_end], extremely stable and has very low turnover rate
○ Elastic fibers, which are composed of elastin and [blank_start]glycoprotein[blank_end] microfibrils, allow tissue to expand and contract.
○ Elastin has a highly cross-linked, insoluble, amorphous structure
Elastin is synthesized from the precursor [blank_start]tropoelastin[blank_end]- Asplicing
- Binsoluble
- Ctropoelastin
- Dglycoprotein
7Collagen is degraded by collagenases [and other matrix metalloproteinases (MMPs)]:
1. Tissue Collagenase
○ Function in the growth and remodeling of tissues
2. Bacterial Collagenase
○ Clostridium histolyticum collagenase ([blank_start]gangrene[blank_end])
○ Breaks down connective tissue barriers
○ Allows the bacteria to spread
3. Elastin is degraded by [blank_start]elastase[blank_end].
○ is a [blank_start]serine[blank_end] protease
○ will hydrolyze elastin but not collagen
○ will hydrolyze other proteins
○ functions in tissue upkeep and remodeling
• A genetic defect leads to a1-[blank_start]antitrypsin[blank_end] deficiency
○ Emphysema results from an imbalance between a1-antitrypsin and elastase, resulting in increased degradation of extracellular matrix components
○ [blank_start]Emphysema[blank_end] - accompanied by a marked loss of elastin in the lungs
○ Cigarette smoke increases the number of neutrophils and macrophages into the lungs – [blank_start]decreases[blank_end] a1-antitrypsin, [blank_start]increases[blank_end] elastase; increases risk of emphysema
Deficiency can also lead to scarring or [blank_start]cirrhosis[blank_end] of the liver- Aelastase
- Bserine
- Cgangrene
- Dantitrypsin
- EEmphysema
- Fdecreases
- Gcirrhosis
- Hincreases
Informationen
- Beschreibung
- Biochemistry Quiz am Collagen and Elastin, erstellt von Fatima G. am 21/08/2019.
- Autor
- Fatima G.
- Sprache
- English
- Aufrufe
- 0
- Schlagwörter
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