Module 6: Amino Acids and Proteins Obj. 6 Flashcards

1
Q

reaction of the Biuret method for total protein

A

peptide bonds in protein + cupric ions at an alkaline pH = violet color complex

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2
Q

Purpose of potassium iodide in Biuret method

A

prevents auto-reduction of Cu++ to Cu+

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3
Q

Purpose of sodium-potassium-tartrate in Biuret method

A

maintain Cu++ in solution at alkaline pH

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4
Q

Preferred type of sample for Biuret method

A

serum

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5
Q

Which samples are not suitable for Biuret method? Why?

A

urine - ammonia present interferes with test

CSF - method is not sensitive enough

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6
Q

uses for dye-binding methods

A

albumin, urine total protein and electrophoretic quantitation

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7
Q

requirements of dye-binding methods

A

two separate wavelengths for measuring absorbance of the free dye and the dye-protein complex
Minimal interfering substances (ex. Hb, bili, lipemia)
Constant temp

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8
Q

Principle of protein electrophoresis

A

separation of charged molecules on support medium in an electrical field
Proteins in alkaline solution have net neg. charge

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9
Q

what does pH determine in EP

A

the state of ionization of the charged groups of the constituent amino acids of proteins and therefore their electrical charges

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10
Q

what does ionic strength determine in EP

A

resolution and mobility

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11
Q

buffer typically used in serum EP? What is its pH?

A

Barbital based buffer

pH 8.6

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12
Q

anions, cations, anode, cathode definition

A

anions are negatively charged ions that move towards the anode (pos pole)

cations are positively charged ions that move towards the cathode (neg pole)

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13
Q

which form are proteins in and which pole do they migrate towards in typical protein EP

A

proteins will have negative charge (anions) and will move towards anode (pos pole)

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14
Q

Effect on mobility and resolution of low ionic strength buffers

A

faster migration

low resolution

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15
Q

Effect on mobility and resolution of high ionic strength buffers

A

slow migration

high resolution

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16
Q

what is electroendosmosis and how does it occur

A

movement of buffer fluid itself under the influence of applied voltage in the electric field

Water molecules in close association with medium become pos charged and are attracted towards the cathode
Movement of water carries some proteins backwards
Gamma region

17
Q

ohms law

A

voltage (V) = Current (I) x Resistance (R)

18
Q

effect on migration from constant current

A

Constant current: stabilizes migration rate

19
Q

5 bands produced in serum EP

A
Albumin
Alpha 1
alpha 2
beta
gamma
20
Q

⍺ 1 band contains

A

⍺1-fetoprotein
⍺1-antitrypsin
⍺1-lipoproteins
Thyroid binding globulin

21
Q

⍺2 band contains

A

Haptoglobin
Ceruloplasmin
⍺2-macroglobulin
Pre-Beta-lipoprotein

22
Q

Beta-globulin contains

A
Transferrin
Hemopexin
B-lipoprotein
B2-microglobulin
C3 and C4
CRP
Free Hb
23
Q

gamma-globulin band contains

A

immunoglobulins IgG, IgM, IgD, IgE

24
Q

2 primary functions of albumin in the body

A

transport of substances in plasma

Regulating osmotic pressure and fluid balance in the extracellular compartment

25
Q

protein likely responsible for distinct band in the beta-gamma interzone

A

fibrinogen (migrates between these two bands; major protein in fibrin clot; plasma sample used)

IgA

26
Q

bands affected in an acute phase reaction

A

Alpha 1, alpha 2, beta

Often decreased ALB

27
Q

What is immunofixation EP

A

improved form of immunoEP
Different antisera on each track (3 heavy chains, 2 light chains)
once stained, will show levels of Ig

28
Q

Common clinical conditions associated with Decreased Albumin

A
liver cirrhosis
malnutrition
burns
kidney disease
acute phase reaction
cancer
29
Q

Common clinical conditions associated with Alpha one fetoprotein

A

increased in spina bifida

30
Q

Common clinical conditions associated with Haptoglobin

A

decreased in liver disease, hemolytic anemia and liver failure
Increased in inflammation, Hodgkins disease and myocardial infarction

31
Q

Common clinical conditions associated with Ceruloplasmin

A

increased in pregnancy

Decreased in wilsons disease

32
Q

Common clinical conditions associated with Transferrin

A

increased in anemia

decreased in nephrosis and liver disease

33
Q

Typical EP findings in Multiple Myeloma

A

Monoclonal peak in gamma region

Follow up with IFE

34
Q

Typical EP findings in Liver Cirrhosis

A

increased IgA (shown as beta gamma bridging)