AA, Proteins, Enzymes (Biochem) Flashcards Preview

Kaplan Biochem and Genetics > AA, Proteins, Enzymes (Biochem) > Flashcards

Flashcards in AA, Proteins, Enzymes (Biochem) Deck (31):
1

AA that have R-groups with + charge at physiologic pH

- Arginine and Lysine (both are found in histones)
- histidine has a + charged R group at neutral pH, that is found at the active site of enzymes

2

AA that have R-groups with - charge at physiologic pH

aspartic acid and glutamic acid

3

AA that buffers well in proteins at physiologic pH

Histidine

4

Essential AA

P - phenylalanine (NOT PROLINE)
V - valine
T - threonine (NOT TYROSINE)

T - tryptophan (NOT TYROSINE)
I - isoleucine
M - methionine

H - histidine
A - arginine (only essential in kids*)
L - leucine
L - lysine

*kids have + N balance and need more N

5

Negative Nitrogen balance associated with

- protein malnutrition (kwashiorkor)*
- dietary deficiency of even one essential AA
- starvation
- uncontrolled diabetes
- infection

* Don't confuse with marasmus = chronic deficiency of calories. These patients do not present with edema like patients with kwashiorkor

6

Positive Nitrogen balance associated with

- growth
- pregnancy
- recovery phase of injury/surgery
- recovery from condition associated with negative nitrogen balance

7

a child with PKU has how many essential AA?

- Normal adults only need 9 (arginine is only essential in kids)
- normal kids only need 10 (arginine)
- kids with PKU need 11 (also need tyrosine)

8

Do competitive or non-competitive inhibitor increase Km?

Competitive inhibitors increase Km

9

How do you change Vmax?

add more enzyme

10

noncompetitive inhibitors

- no effect on Km
- DECREASE Vmax

11

Km =

substrate concentration at which enzyme is at 1/2 Vmax

12

Competitive inhibitors

- increase Km
- no effect on Vmax

13

This enzyme is a major precursor in gluconeogenesis

Alanine (nonpolar)

14

AA with Nonpolar, aliphatic side chains

- glycine (gly)
- alaine (Ala)
- valine (Val)
- leucine (Leu)
- ieoleucine (Ile)
- proline (Pro) (has secondary amine)
6 AA with Nonpolar, aliphatic side chains
* VP GAILe
- A is not Arginine
- L is isoleucine, not lysine

15

Hartnup's Disease

- AR
- affects absorption of non polar AA
- tryptophan not absorbed therefore can't make serotonin, melatonin, niacin
- symptoms: photosensitivity, nystagmus, tremor, ataxia (neurological)
- Tx: high protein diet

16

AA with aromatic side chains

3 total:
- phenylalanine (Phe)
- tyrosine (Tyr)
- tryptophan (Trp)

- tryptophan used to make serotonin, melatonin, niacin
- tyrosine is used to make T3, T4, and melanin

17

AA used to make catecholamines T3, T4 and precursor to melanin

Tyrosine

18

AA with polar, uncharged R groups

- serine (Ser)
- threonine (Thr)*
- cysteine (Cys)
- asparagine (Asn)
- glutamine (Gln)
- methionine (Met can be considered nonpolar or polar bc has S)

* Threonine target of O-glycosylation in Golgi
*STAG MC
- A = asparagine
- T = threonine

19

which AA is the precursor to NO

- Arginine
- Remember: Essential AA in kids

20

Body uses which AA to carry NH3 in blood

Glutamine

21

AA that contain Sulfur

- Cysteine and Methionine
- targets of N-glycosylation that begins in ER

22

protein breakdown occurs in 2 locations

1. lysosomal proteases digest endocytosed proteins
2. large cytoplasmic complexes (proteasomes) digest older or abnormal proteins that have been covalently tagged with ubiquitin for destruction

23

Which AA are precursors for catecholamines

phenylalanine and threonine
(catecholamine ex: Norepinephrine, Epinephrine, Dopamine)

24

Hydrophilic AA

- Positively charged AA (3), Negatively charged AA (2), Polar uncharged AA (6)
- 11 total: aspartate, glutamate, lysine, arginine, histidine, serine, threonine, cysteine, methionine, asparagine, glutamine

25

Which are branched-chain AA whose metabolism is abnormal in maple syrup urine disease?

valine, leucine and isoleucine (all nonpolar)

26

which AA is a secondary amine whose presence in a protein disrupts normal secondary structure?

proline

27

hydrophobic AA

9 total: glycine, alanine, valine, leucine, isoleucine, proline, phenylalanine, tyrosine, tryptophan

28

Which AA can form serotonin and niacin

Tryptophan

29

- Is Hartnup's disease AD or AR?
- symptoms? what causes them?

- AR
- tryptophan not absorbed therefore can't make serotonin, melatonin, niacin
- symptoms: photosensitivity, nystagmus, tremor, ataxia (neurological)

30

Tyrosine is used to make ??

catecholamines T3, T4 and is a precursor to melanin

31

kids with PKU also need what AA?

tyrosine (+ 10 essential AA for a total of 11)