Exam 1 Biochem

Front 1

ATCase

Back 1

example of allosteric enzyme regulation
-inhibited by CTP
-12 subunits
6 catalytic and 6 regulatory
-2 triplets of catalytic subunites
-3 pairs of regulatory subunits

Front 2

PKA

Back 2

allosteric enzyme regulation example
-2 regulatory sites and 2 catalytic sites
-R has affinity to cAMP

Front 3

how CTP inhibits ATCase

Back 3

CTP binds to the regulatory site of subunit and stabilizes T state
-heterotropic regulation since CTP not substrate

Front 4

What binds PKA and what does it do?

Back 4

cAMP binds to R site of PKA and causes the release of the C sites which can then Phosphorylate other proteins

Front 5

Lactate dehydrogenase is what kind of enzyme regulation?

Back 5

Isozyme
-H4 active in aerobic
M4 active in anaerobic

Front 6

What kin d of activation happens when zymogen converted to enzyme

Back 6

proteolytic activation
-removal of peptide bonds or portion of peptide chain

Front 7

What is common activator of all pancreatic zymogens?

Back 7

trypsin

Front 8

what enzyme converts trypsinogen to trypsin

Back 8

enteropeptidase

Front 9

What converts fibrinogen to fibrin

Back 9

thrombin

Front 10

Function of TPA

Back 10

converts plasminogen to plasmin which dissolves clot
-used to treat heart attack

Front 11

Mechanism of catalytic triad?

Back 11

OH group of Ser becomes O- (alkoxoxide ion)
-O- attacks O=C-N and cleaves C-N
-Oxyanion hole stabilizes the transition state.
-involves covalent catalysis and acid base catalysis

Front 12

how does 2,3 BPG affect hemoglobin O2 affinity?

Back 12

-Binds to T state when by tissue
-binding to partially deoxy Hg allosterically upregulates release of the remaining O2 bound.
-ALlows RBC's to relese O2 near tissues quickly and efficiently.

Front 13

Fetal Hg has higher or lower affinity for 2,3 BPG?

Back 13

Lower
-O2 binding affinity of fetal Hg is higher

Front 14

SIckle cell caused by what mutation?

Back 14

GAG -> GTG
Val 6 for a Glu 6

Front 15

What is collagen composed of?

Back 15

-Gly every 3rd residue
-rich in Pro, Hyp, Ala
-very little tryptophan since so large
-never cysteine since cleaved
-typically Gly-Pro-Hyp

Front 16

Steps in formation of collagen?

Back 16

1. carbohydrate side chains added
2. hydroxylation of proline and lysine
- prolyl hydroxylase and lysyl hydroxylase require vitamin C and Fe++
3. disulfide bridges formed
4. procollagen terminals clipped
5. crosslinks formed b/w fibrils (h bonds) Lys and Hyl portions assist in this at terminal portions to help form fiber

Front 17

What are causes and symptoms of scurvy? Effects formation of what structure?

Back 17

- Caused by vitamin C deficiency
-Prolyl hydroxylase that forms hydroxyproline requires vitmain C
-Hyp stabilizes triple helix of collagen forming INTER-strand H-bonds
-symptoms are skin lesions, blood vessels fragility, poor wound healing, death

Front 18

Osteogenesis Imperfecta (OI) causes and symptoms? Structure affected?

Back 18

-Mutations in type 1 collagen gene (DGI)
-causes large R group AA to be in place of small Gly that disrupts triple helix
-symptoms are bone fractures and dental abnormalities
-thinner dentin (shell teeth)

Front 19

proteins in Dentin matrix and

Back 19

-90% collagen (type 1)
-DSPP
-knockout causes dentin to not be formed from predentin
-causes DGI-2 which is like DGI-1 but only affects teeth rather than bones and teeth
-DMP1
-deficiency causes osteomalacia/rickets(soft bones/dentin)