Mila Jullig - Lecture 2 Flashcards
1
Q
HIV-1 protease
A
- Aspartic protease
- cuts up polyproteins of virus into final products
- very important in viral reproduction
2
Q
caspases
A
- Cysteine proteases
- used in apoptosis, but also in necrosis and inflammation
3
Q
Cathepsin D
A
- Aspartic protease
- involved in lysosomal proteolytic degradation intracellularly
- similar activity to pepsin, but narrow specificity
4
Q
calpains
A
- Cysteine proteases
- used in cell mobility and cycle progression, LTP, cell fusion, memory, apoposis, necrosis
- non-lysosomal Ca activated, neutral proteases
5
Q
Entertopeptidase
A
- Serine protease
- converts trypsinogen to trypsin
6
Q
collagenases
A
- Metalloprotease
- secreted as pro-collagenases, converted by stromelysins
- cleave peptide bonds in carious collagens
7
Q
Trypsin
A
- Serine protease
- catalyses hydrolysis of proteins
- secreted from pancreas into SI as trypsinogen
- activated by Enteropeptidase (serine) by cleavage of trypsinogen activation peptide OR catalysed by trypsin
8
Q
Matrix Metalloproteinases
A
- Metalloprotease
- ECM = provide scaffolding for cells, protect cells and signals go through ECM
- use zinc for catalysis
- secreted in pro form, with cysteine blocking zinc bining site, cleavage of this activates
9
Q
26S proteasome
A
- Threonine protease
- subunits of proteasome
- found in cytosol and/or nucleus of all eukaryotic cells
- degrades damaged or unneeded proteins
10
Q
Chymosin/rennin
A
- Aspartic protease
- secreted by chief cells in abomaum lining of calves
- found in rennet, curdles milk (hhelpful for increasing absorption)
- targets kappa casein (phosphoprotein with phosphates on OH groups of some serine - also glycosylated at some threonine - charged and hydrophillic so soluble in water)
- kappa casein solublises alpha and beta casein in micelles
- chymosin cleaves off hydrophillic portion of kappa casein => no repelling, forms meshworks
11
Q
renin
A
- Aspartic protease
- secreted by the kidney at low blood volumes
- angiotensinogen (from liver) is converted into angiotensin I (10 residues)
- (ACE in lungs and endothelial cells required to convert angiotensin Ito angiotensin II)
- Renin-Angiotensin System - used to elevate BP by increasing volume of blood plasma, lymph and interstitial fluid (by increasing na and h2o readbsorbtion) and increasing arterial vasoconstriction
12
Q
most cathepsins
A
- Cysteine proteases
- found within lysosomes, activated at low pH
- lysosomal degradation
13
Q
Thrombin
A
- Serine protease
- coagulation factor
14
Q
pepsin
A
- Aspartic protease
- one of the main digestive enzymes
- secreted as Pepsinogen from chief cells
- secretion of HCl from parietal cells lowers pH
- low pH causes unfolding and cleavage into active form
15
Q
Chymotrypsin
A
- Serine protease
- secreted from pancreas as chymotrypsin
- activated by trypsin
- helps convert protein and large peptides into amino acids
16
Q
gelatinases
A
- Metalloprotease
- secreted as pro-gellatinases, converted by M-type MP and Matrilysin
- breaks bonds in collagen
17
Q
papain
A
- Cysteine protease
- used as meat tenderiser
- catalyses reactions through…
- — deprotonation (reduction) of Cysteine 25 by Histidine 159 => stronger acid, right microenvironment
- — Cys 25 neucleophilic attack of carbonyl carbon in substrate backbone => peptide bond broken, , half substrate free
- — complex deacylated by water => remaining substrate removed and back to original state.
- metals inhibit papain activity
- preference to cleave with large hydrophobic AA in P2 position
- broad specificity, breaks bonds of basic AA
18
Q
Elastase
A
- Serine protease
- secreted from pancreas to duodenum as proelastase
- activated by trypsin
- catalyses digestion of elastin (lots in meat)
19
Q
Which two catalytic groups aren’t mentioned and why?
A
- Glutamate proteases - found in some fungi and baceria
- Aspargine peptide lyases - only class that arent hydrolases - cleave themselved. Found in viruses
