Basic Aspects of Biochemistry: Amino Acids, Proteins, Enzyme Kinetics

Question 1

normal PH range of arterial blood

Answer 1

7.37-7.43

Question 2

Hydrophobic amino acids with aliphatic side group:

Answer 2

V, L, I, G, A, P.

Question 3

Draw the reaction dissociation of 7 ionizable aa’s at PH below and above the PKa’s: D (PKa= 3.9) E (4.1) H (6.0) C (8.4) Y (10.5) K (10.5) R (12.5)

Answer 3

Ionizable groups on amino acids carry protons at low pH (high [H+]), which dissociate as
the pH increases. If the pH is below an ionizable group’s pKa, then the group will be protonated.
Once the pH is above the pKa, the group will be deprotonated.

Question 4

two major causes of resp. acidosis

Answer 4

accumulation of metabolic acids and ingestion of comp that metblz 2 acid

Question 5

Structure of R at PH< Pka

Y

Answer 5

TYR, PKa= 8.4

Question 6

lungs and kidneys compensatory behavior during METABOLIC ACIDOSIS

Answer 6

met. acidosis –> hypERventilation and the release of CO2. The kidneys excrete NH4+, which contains H+ buffered by ammonia

Question 7

relatively more polar aromatic amino acid

Answer 7

Tyr, Y > Trp, W

Question 8

Structure of R at PH< Pka

H

Answer 8

HIS

PKa= 6.0

Question 9

7 amino acids with ionizable groups and the corresponding PKa’s:

Answer 9

Asp 3.9 Glu 4.1 His 6.0 Cys 8.4 Tyr 10.5 Lys 10.5 Arg 12.5

Question 10

Causes metabolic alkalosis

Answer 10

inc. HCO3-

Question 11

Structure of R at PH< Pka C

Answer 11

CYS PKa= 8.4

Question 12

causes the retention of CO2 by the lungs and leads to a respiratory acidosis

Answer 12

hypOventilation

Question 13

name a few acidic comps that can cause metabolic acidosis upon their accumulation

Answer 13

1- lactic acid 2- ketone bodies:(B-hydrozybutyrate and acetoacetate) 3- B-hydroxybutyric acid 4- acetoacetic acid

Question 14

hupOventilation (acid-base disturbance)

Answer 14

respiratory acidosis due to CO2 retention by the lungs

Question 15

purpose of drugs that inhibit H+/K+ ATPase of parietal cells

Answer 15

to lower the [H+] (inc. the PH of stomach content and to lessen the esophageal damage ( when gastroesophageal sphincter fails to close, gastric reflux disease occurs).

Question 16

Structure of R at PH< Pka

E

Answer 16

GLU

• CH2-CH2-COOH
• (CH2)2-COOH

PKa= 4.1

Question 17

The max capacity of a buffer

Answer 17

At the PKa,whete [A-] and [HA] are equal the buffer has its max capacity.

Question 18

NH4+ and Acid-Base disturbance

Answer 18

When metabolic acidosis –> kidneys excrete H+ buffered by ammonia (NH3)

Question 19

The compounds that upon digestion cause metabolic acidosis

Answer 19

These comps results in accumulation of acid upon digestion: methanol, ethylene glycol

Question 20

W

Answer 20

Trp

Question 21

hypERventilation (acid-base disturbance)

Answer 21

resp. alkalosis

Question 22

Positively charged amino acids are:

Answer 22

basic Arg, R Lys, K His, H

Question 23

Henderson–Hasselbalch equation

Answer 23

pH = pK + log10 [A−]/ [HA]

Question 24

sulfhydryl oxidation

Answer 24

form disulfide

Question 25

The amino acid that is NOT of L-configuration and dose NOT have Asymmetric a-carbon:

Answer 25

glycine.

Question 26

Structure of R at PH< Pka K

Answer 26

K LYS

PKa= 10.5

Question 27

selenocysteine

Answer 27

unique aa in that a serine residue is converted to selenocysteine while attached to a tRNA.

Question 28

Negatively charged amino acids are:

Answer 28

acidic Asp, D- Aspartate Glu, E- Glutamate

Question 29

sulfur-containing amino acids

Answer 29

Met, M Cys, C

Question 30

Structure of R at PH< Pka

R

Answer 30

ARG, PKa= 12.5

Question 31

Non-polar aromatic amino acid

Answer 31

Phe, P

Question 32

Polar, uncharged amino acids

Answer 32

Asn,N (aspargine) Gln, Q (glutamine) Ser, S (hydroxyl group) Thr, T (hydroxyl group)

Question 33

1. Name two major buffers of blood?
2. How do they work in conjugation with other organs to maintain the normal PH?

Answer 33

1. Major buffers:
   
   • Bicarbonate (HCO3-/H2CO3)
   • Hemoglobin (Hb/HHb)
2. Organs:
   
   • Kidney- excreting protons
   • Lung- CO₂ exchange

Question 34

Structure of R at PH< Pka

D

Answer 34

Asp

-CH2-COOH

PKa= 3.9

Question 35

Amino acids capable of hydrogen bonding:

Answer 35

T, S.