Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochemistry > Enzyme Mechanisms > Flashcards

Enzyme Mechanisms Flashcards

1
Q

what catalyzes the hydrolytic cleavage of pepetide bonds

A

Serine proteases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are serine proteases found in the pancreas

A

trypsin
chymotrypsin
Elastase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

which molecule has about 3 polypeptides linked with disulfide bond

A

Chymotrypsin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Chymotrypsin with cleave to whcih side chain

A

hydrophobic/aromatic side chain, Trp, Phe, Tyr

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what amino acid forms the catalytic triad in chymotrypsin

A

His, Ser, Asp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

chymotrypsin has how many mechanism

A

2-step, acylation and deacylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

which protease catalyze peptide hydrolysis but not via direct addition of water to the peptide bond

A

Chymotrypsin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

protein cleave peptide bonds but also

A

slow cleave esters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

the first step pf chymotryopsin results to

A

p-nitrophenylacetate, fast reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what can deactivate a serine residue

A

DIFP (diisopropyl phosphofluoridate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what makes Ser a better nucleophile

A

H-bonded chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

When His 57 abstract proton from Ser 195, it is a

A

general base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

HIs 57 is stabilized by

A

Asp 102 carboxylate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The second step of chymotrypsin reeaction mechanism

A
  • nucleophilic attack of alkoxide ion on peptide carbonyl carbon leads to tetrahedral intermediate (acyl-enzyme)
    *negatively charged O stabilized by oxyanion hole through Ser & Gly
    H bond to Gly 193 only occur in this intermeiate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what mechanism is when alkoxide ion on peptide carbonyl leads to tetrahedral intermediate

A

Transition State

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what happens in step 3 of chymotrypsin reaction

A

tetrahedral intermediate collapses reforming C=O and breaking C-N bond
hist 57 acts a a general acid to protonate amino group make it a better leaving group

17
Q

what happens in step 4

A

Acyl-enzyme intermediate remains
N-terminal peptide is bound to covaltny bound to ser 195
first part is released

18
Q

what happens in step 5

A

this 57 acts as a general base again and abstract proton from water
OH- acts a nucleophile and attacks C=O

19
Q

what happens in step 6

A

OH- Attack on C=O leads to tetrahedral intermediate
negative charge on O stabilized by oxyanion hole

20
Q

what haooens in step 7

A

tetrahedral intermediate collapses, reforming C=O
C-O bonds is broken as His acts as general acid to facilitate displacement to Ser

21
Q

HIV protease uses which amino acid

A

aspartate

22
Q

active site asparate

A

aspartyl protease

23
Q

does water directly attach the peptide bond in HIV protease or covalent enzyme-susbtrate complex true/fasle

A

yes

24
Q

HIV protease cleaves amino acid

A

Phe
pro

25
Q

what happens in HIV protease

A

General acid base catalysis, water attacks carbonyl carbon on Asp generating a tetrahedral stabilizes by H-BONDING
Tetrahedral intermediate collapses, amino group leaves

26
Q

enolase uses

A

divalent catiob

27
Q

what ions are used in stabilizing enolate intermediate

A

Mg2+

28
Q

Lys 345 acts as a in enolase

A

general base

29
Q

what does Glu 211 acts as making -OH a better leaving group;H2O

A

Glu 211

30
Q

Antibiotics target – in bacteria

A

peptidydoglycan synthesis through cellwall

31
Q

peptidoglycan is made up of

A

polypeptide cross linked by peptides

32
Q

what is first step in peptidoglycan chain

A

*cross linking is carried by out a transpeptidase
*Active site Ser attachs carbonyl of peptide bond
*covalent linkage between substrate peptidoglycan and transpeptidase

33
Q

what happens in step 2

A

breaks bonds again and replaces with a new bond forming by cross linking

34
Q

transpeptidase are inhibited by

A

Beta-lactam antibiotics

35
Q

what can make bacteria antibiotic resistant

A

Beta-lactamases by breaking/changing the ring

36
Q

what stabilizes a negative ion in chymotrypsin

A

Oxyanion hole

37
Q

what holds the aromaticring in place

A

hydrophobic pocket

38
Q

what mechanism is in step 2

A

transition state & covalent catalysis

Biochemistry (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions