Proteases 2 Flashcards
What are the serine proteases?
Trypsin Enteropeptidase Elastase Chymotrypsin Thrombin
What are the cysteine proteases?
calpains
caspases
most cathepsins
papain
What are the aspartic proteases?
pepsin Cathepsin D renin Chymosin HIV1 Protease
What are the metallo proteases?
MMPS,
collagenases
gelatinases
What are the threonine proteases?
26S proteasome
What are caspases?
Cysteine-dependant-aspartate-directed proteases that function in apoptosis, necrosis and inflammation
What is enteropepitidase?
An enzyme which activates trypsinogen by forming trypsin for protein digestion through cleavage of the trypsinogen activation peptide
What is rennin?
chymosin which is a protease produced in the abomasum lining of calves where curdles milk so it stays long enough in stomach to enable processing before its released into the intestines
The typical target of this enzyme is casein, where it cleaves the kappa casein so the micelles (which normally makes the hydrophobic proteins in milk soluble) so the charged tails are removed and the micelles clump together
What is the protease system that regulates blood pressure?
Renin-angiotensin system, as If blood pressure is low, the kidneys secrete renin into the bloodstream. Renin cleaves off most of angiotensinogen, leaving a 10 residue fragment (= angiotensin I)
Angiotensin Converting Enzyme (ACE) in the vessel walls trims off two more residues, leaving the active product: angiotensin II
What are Cathepsins
a diverse group of cysteine proteases, not all are cysteine proteases. Most work within lysosomes where they become activated at the low pH
What is the protease system used in mammalian protein digestion?
The aspartic protease pepsin is released into the stomach as pepsinogen where it is activated by autocatalysis by the low pH, and proteins are cleaved into large chunks
In the intestine 4 key serine proteases are sued enteropeptidase activates trypsinogen to trypsin
Trypsin will then digest proteins, activate more trypsinogen and activate proelastase (aloowing elastase to degrade elastin) as well as activating chymotrypsinogen
These proteases are used with carboxypeptidases and aminopeptidases to covert proteins to free amino acids which are absorbed by the organism
What is the role of HIV-1 protease?
A apsartic protease which cuts up the polyproteins produced by the HIV virus into the proteins which can be assembled to produce the mature viral progeny
What s papain?
a broad specificity cysteine protease, catalytic mechanism has been found to be a dyad with Cys-25 and His-159,
prefers to cleave bonds of basic amino acids, leucine or glycine
What are MMPs?
matrix metalloproteinases, which all use Zn2+, the pro-proteases contain a strategically positioned cysteine which binds and blocks the Zn2+ bound to the Zn2+ binding site
Activated by cleavage of the prodomain with cys residue
include collagenases, stromelysins, gelatinases, matrilysins and M-type metalloproteases
What are threonine proteases?
associated with intracellular protein degradation by the proteasome
