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CMBM Exam 2 > Dietary Proteins > Flashcards

Dietary Proteins Flashcards

1
Q

Positive nitrogen balance

A
  • occurs when a person is producing new tissue (i.e., during growth, pregnancy, recovering from trauma) so the protein is being used at a higher rate than excreted.
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2
Q

Negative Nitrogen balance

A
  • A negative nitrogen balance develops when there isn’t enough dietary protein for daily needs, or when some essential amino acids are missing from the diet causing an incomplete complement of the 20 amino acids - can be brought on by illness - Since protein is continuously being made, the body must break down functional proteins to use.
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3
Q

Essential amino acids

A

(Pvt. Tim Hall) - phenylalanine - valine - threonine - tryptophan - isoleucine - methionine - histidine - arginine - lysine - leucine * Tyrosine is synthesized from phenylalanine (essential) * Cysteine synthesis requires the sulfur from methionine (essential) * Adults do not require dietary arginine, but arginine is required for infants (especially preterm babies) due to the lack of synthesizing enough Arg

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4
Q

Quinoa

A
  • only grain that contains all the essential amino acids
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5
Q

Kwashiorkor

A
  • protein deprivation > total calorie deprivation Results: - poor growth - muscle wasting - edema - diarrhea - increased infections Can occur in elderly; not eating balanced meals Other causes: - chronic alcoholism - poverty - self-imposed dietary restrictions - some hospital settings
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6
Q

Marasmus

A
  • total calorie deprivation > protein deprivation
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7
Q

Chief cells

A
  • in the stomach - secrete pepsinogen; activated to pepsin * degrades dietary protein to smaller peptides
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8
Q

G-cells

A
  • in stomach - secrete hormone Gastrin in response to food entering the stomach
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9
Q

Aminopeptidases

A
  • produced by intestinal mucosal cells - cleave amino acids from the N-terminus of peptides - Endopeptidases, dipeptidases, and aminopeptidases, located on the surface of intestinal mucosal cells, cleave peptides to di- and tripeptides and amino acids, which are transported into the mucosal cells
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10
Q

Enteropeptidases

A
  • hydrolyze peptide bonds within the peptide chain Examples: Pepsin, trypsin, chymotrypsin, elastase
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11
Q

Pancreas digestive enzymes

A
  • trypsinogen - chymotrypsinogen - procarboxypeptidase A - procarboxypeptidase B - proelastase
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12
Q

EXOPEPTIDASES

A
  • remove AA’s one at a time from one end or the other Aminopeptidases - remove the amino acid from the N-terminus Carboxypeptidases - remove the amino acid from the C-terminus
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13
Q

How do amino acids get into the cell?

A

Glutathione assists - GGT is enzyme - resynthesize GSH after (requires energy) Na-K+ ATPase assists - depends on Na+ conc. * amino acids are cotransported into cell w/ Na+ - requires energy

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14
Q

Gamma-glutamyl transpeptidase (GGT) transporter

A
  • use glutathione to bring amino acids into a cell * glutathione assists * resynthesizes GSH after * Na+- K+ ATPase assists - GGT is important as a marker of liver function
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15
Q

Nitrogen travels through blood stream as

A
  • alanine - glutamine
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16
Q

Pyridoxal phosphate

A
  • derivative of vit. B6 - cofactor in aspartate aminotransferase
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17
Q

Vitamin B6 deficiency

A

caused by poor absorption of nutrients in the gastrointestinal tract - alcoholism - chronic diarrhea - certain drugs that activate the vitamin - genetic disorders that inhibit metabolism of the vitamin - starvation

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18
Q

Vitamin B6 deficiency symptoms

A
  • nervousness - irritability - insomnia - muscle weakness - difficulty in walking - may produce fissures and cracking at the corners of the mouth
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19
Q

AST and ALT

A
  • elevated in nearly all liver diseases - particularly high in extensive cellular necrosis - ALT is more specific than AST for liver disease but AST is a more sensitive indicator b/c the liver contains larger amounts of AST
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20
Q

Glutamate dehydrogenase

A

• Requires either NAD or NADP • Readily reversible • Allosteric activators (toward α-ketoglutarate) are ADP and GDP • Allosteric inhibitors (toward glutamate) are ATP and GTP

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21
Q

Carbamoyl phosphate synthetase 1 (CPS-1)

A
  • rate limiting, regulated step in urea production - converts NH4 and CO2 using 2 ATP into carbamoyl phosphate - CPS-I is allosterically activated when large amounts of amino acids are present in circulation
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22
Q

Ornithine transcarbamoylase

A
  • carbamoyl phosphate and ornithine into citrulline
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23
Q

ENDOPEPTIDASES

A
  • hydrolyze peptide bonds within the peptide chain - Examples: * Pepsin, trypsin, chymotrypsin, elastase
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24
Q

Amino acids specifically used for ketogenesis

A
  • lysine - leucine * both can only synthesize acetoacetate
25
Q

Branch chain amino acids (BCAA)

A
  • valine - leucine - isoleucine
26
Q

Branch chain amino acids (BCAA) functions

A
  • α-keto acids from BCAA are used for energy, mainly in the muscle and other tissues (not liver) * Liver spares BCAA for the other tissues’ energy needs * liver lacks BCAA transaminase - valine can go into gluconeogenesis - leucine can go into ketogenesis - isoleucine can go into both
27
Q

Catabolism of BCAA

A

1) BCAA undergoes transamination to remove nitrogen forming Branched-chain α-Ketoacids 2) Branched-chain α-Ketoacids are then enzymatically oxidative decarboxylated to Acyl-CoA and Derivatives BCAA ===> Branched-chain α-Ketoacids ===> Acyl-CoA and Derivatives

28
Q

Branched-chain α-ketoacid dehydrogenase (BCKD) cofactors

A

• NAD • FAD • CoA • TPP • Lipoic acid

29
Q

Deficiency in Branched-chain α-ketoacid dehydrogenase (BCKD)

A

• Appearance of BCAA in the urine and give it the maple syrup odor • Maple Syrup Urine Disease (MSUD)

30
Q

3 Related Dehydrogenases

A

Pyruvate Dehydrogenase α-Ketoglutarate Dehydrogenase Branched Chain α-Ketoacid Dehydrogenase

31
Q

Pyruvate Dehydrogenase α-Ketoglutarate Dehydrogenase and Branched Chain α-Ketoacid Dehydrogenase 5 same cofactors

A

• NAD • FAD • CoA • TPP • Lipoic acid

32
Q

Pyruvate Dehydrogenase α-Ketoglutarate Dehydrogenase and Branched Chain α-Ketoacid Dehydrogenase differences

A

α-KG & α-KA DH ▶ 3 enzymes ▶ Lacking regulation by kinase, phosphatase PDH ▶ 5 enzymes ▶ Added regulation by extra kinase, phosphatase

33
Q

Amino acids that are both gluconeogenic and ketogenic

A

Aromatic - phenylalanine - tyrosine - tryptophan

34
Q

L-phenylalanine to L-tyrosine enzyme and cofactor

A
  • Phenylalanine hydroxylase - BH4 cofactor
35
Q

Tyrosine is used to make

A
  • fumarate and acetoacetate - catecholamines - melanin - melatonin - thyroid hormone
36
Q

Phenylketonuria (PKU-I) defect

A
  • deficiency in phenylalanine hydroxylase * mutation in gene phenylalanine hydroxylase (PAH)
37
Q

Phenylketonuria (PKU-I) symptoms

A

• Mental retardation • Seizures • Microcephaly • Failure to grow

38
Q

PKU-II and III defect

A
  • deficiency of dihydro-biopterin reductase or synthetase
39
Q

PKU-II and III symptoms

A

• Alternative path to PKU • Results in ↓ Synthesis of catecholamines, serotonin • Neurological abnormalities

40
Q

BH4 is a cofactor for

A

Synthesis of: - catecholamines - serotonin - tyrosine

41
Q

Phenylketonuria (PKU-I) treatment

A
  • large doses of LNAAs (W/O Phe) decreases Phe levels in cerebrospinal fluid and brain, improving cognitive functions
42
Q

Deficiency of dihydro-biopterin reductase or dihydro-biopterin synthetase results in

A
  • hyperphenylalaninemia - decreased synthesis of catecholamines and serotonin
43
Q

Some SAM-involved reactions:

A
  • Norepinephrine → Epinephrine - Nucleotides →Methylated nucleotides - Guanidinoacetate → Creatine (latter) - Acetylserotonin → Melatonin (latter) - Precursor → Choline (see later)
44
Q

S-Adenosylmethionine (SAM) function

A
  • donates a methyl group to what ever needs it * Methyltransferase enzymatically enables this - becomes S-Adenosyl homocysteine * Homocysteine can either go back to make methionine or cysteine
45
Q

Homocysteine to Methionine enzyme

A
  • methionine synthase
46
Q

Homocysteine to Cysteine enzyme

A
  • Cystathionine synthase
47
Q

Homocystinuria causes

A

Lack of one of these factors: - vitamin B12 - vitamin B6 - folate - Methionine synthase - Cystathionine synthase

48
Q

Histidine to Histamine enzyme

A
  • PLP * vitamin B6 cofactor
49
Q

Creatine/Creatine phosphate synthesis

A
  • Glycine gains a Guanidio group from Arginine forming guanidinoacetate * occurs in the kidney - guanidinoacetate is then methylated by SAM to Creatine * occurs in the liver - creatine can then be phosphorylated to form creatine phosphate * sent to the muscle and brain
50
Q

Elevated Creatinine plasma levels can be caused by

A
  • kidney malfunction - MI
51
Q

Creatinine formed from

A
  • dehydration of Creatine - dephosphorylation of Creatine phosphate
52
Q

Creatinine can be used to estimate

A
  • muscle mass
53
Q

Carnatine derived from

A
  • methylation of LYSINE by SAM (methionine)
54
Q

Excitatory neurotransmitters from AA

A
  • glutamate - aspartate
55
Q

Inhibitory neurotransmitters from AA

A
  • glycine - GABA
56
Q

GABA synthesis

A
  • Glutamate is decarboxylated by PLP (cofactor: vit. B6) GABA
57
Q

Serotonin synthesis

A
  • Tryptophan is hydroxylated by BH4 to another molecule which is then synthesized to Serotonin by LPL (cofactor: vit. B6) - serotonin can be used t- synthesize melatonin
58
Q

Choline and Acetylcholine synthesis

A
  • SERINE ===> ethanolamine - ethanolamine ===> CHOLINE (SAM adds 3 methyl groups - CHOLINE + acetyl-CoA ===> ACETYLCHOLINE * acetylcholinesterase breaks down acetylcholine to choline + acetyl group * choline synthesis needs SERINE and METHIONINE

CMBM Exam 2 (13 decks)

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