AA, Proteins, Enzymes (Biochem) Flashcards

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1
Q

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

A
  • 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

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2
Q

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

A

aspartic acid and glutamic acid

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3
Q

AA that buffers well in proteins at physiologic pH

A

Histidine

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4
Q

Essential AA

A

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

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5
Q

Negative Nitrogen balance associated with

A
  • 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
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6
Q

Positive Nitrogen balance associated with

A
  • growth
  • pregnancy
  • recovery phase of injury/surgery
  • recovery from condition associated with negative nitrogen balance
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7
Q

a child with PKU has how many essential AA?

A
  • 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)
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8
Q

Do competitive or non-competitive inhibitor increase Km?

A

Competitive inhibitors increase Km

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9
Q

How do you change Vmax?

A

add more enzyme

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10
Q

noncompetitive inhibitors

A
  • no effect on Km

- DECREASE Vmax

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11
Q

Km =

A

substrate concentration at which enzyme is at 1/2 Vmax

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12
Q

Competitive inhibitors

A
  • increase Km

- no effect on Vmax

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13
Q

This enzyme is a major precursor in gluconeogenesis

A

Alanine (nonpolar)

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14
Q

AA with Nonpolar, aliphatic side chains

A
  • 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
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15
Q

Hartnup’s Disease

A
  • 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
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16
Q

AA with aromatic side chains

A

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
Q

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

A

Tyrosine

18
Q

AA with polar, uncharged R groups

A
  • 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
Q

which AA is the precursor to NO

A
  • Arginine

- Remember: Essential AA in kids

20
Q

Body uses which AA to carry NH3 in blood

A

Glutamine

21
Q

AA that contain Sulfur

A
  • Cysteine and Methionine

- targets of N-glycosylation that begins in ER

22
Q

protein breakdown occurs in 2 locations

A
  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
Q

Which AA are precursors for catecholamines

A

phenylalanine and threonine

catecholamine ex: Norepinephrine, Epinephrine, Dopamine

24
Q

Hydrophilic AA

A
  • 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
Q

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

A

valine, leucine and isoleucine (all nonpolar)

26
Q

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

A

proline

27
Q

hydrophobic AA

A

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

28
Q

Which AA can form serotonin and niacin

A

Tryptophan

29
Q
  • Is Hartnup’s disease AD or AR?

- symptoms? what causes them?

A
  • AR
  • tryptophan not absorbed therefore can’t make serotonin, melatonin, niacin
  • symptoms: photosensitivity, nystagmus, tremor, ataxia (neurological)
30
Q

Tyrosine is used to make ??

A

catecholamines T3, T4 and is a precursor to melanin

31
Q

kids with PKU also need what AA?

A

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