Lecture 24: Enzymology Flashcards Preview

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Flashcards in Lecture 24: Enzymology Deck (22)
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1
Q

Which disease is associated with increase in troponins serum?

A

Cardiac diseases

2
Q

Isozymes

A

Catalyze the same biochemical reactions

Have multiple forms of the same enzyme

Have different biochemical and immunological properties and amino acid compositions

Different organs contain different isozymes

3
Q

What can result from cellular injury

A

INCREASED levels of intracellular enzymes in serum

4
Q

Creatine Kinase (CK) levels and ATP?

Whats the relationship

A

At high ATP levels:
-Creatine phosphate (CrP) is formed

At high CrP levels:
-ATP is formed using the ENERGY RICH CrP

(Found in heart)

5
Q

Creatine Kinase (CK)

  • Uses?
  • Subunits?
  • Isozymes?
A

-Injury marker

Subunits:

  • B
  • M

3 Iso:

  • CK-BB (CK-1) –>Brain
  • CK-MB (Ck-2) —>little skeletal muscle, mostly heart
  • CK-MM (Ck-3) –>Mostly skeletal muscle

ALL CONTRIBUTE TO THE HEART

6
Q

Time frame for serum in MI Markers

Ck-MB

LDH

A

Ck-MB:
-Peaks after 24 hours

LDH: (Lactate dehydrogenase)
-Peaks after 48 hours

7
Q

LDH (Lactate dehydrogenase)

Isozymes

A

LDH-1:
-More heart than RBC

LDH-2:
-More RBC than heart

(Indicates problem if both are too high)

8
Q

Normal serum levels for LDH

Mi episode serum levels for LDH

A

Normal
-shows low LDH-1/LDH-2 ratio

Mi Episode

  • Heart LDH isozymes increase
  • High LDH-1LDH-2 ratio
9
Q

Mycardial infarcation

Ck levels

troponin levels

Measuring?

A

Def: Heart Attack

  • Leads to increase of total CK and CK-MB
  • Increase in total CK-MB and CK ration indicates a large area of damage to the HEART muscles

(Ck-MB/total CH ratio >6%)
(Ck-MB/total CK ratio >3% and troponins are increased)

Troponins:
Increase in cardiac troponins

Measurements:

  • Electrophoresis
  • RIA (Radioimmunoassay)
  • Elisa (Enzyme-linked immunosorbent Assay)
10
Q

Troponins?

Types?

A

Proteins involved with muscles contraction

Types:

1) Cardiac Troponin I:
- cTnI: Inhibition of actomyoscin ATPase

2) Cardiac Troponin T:
- cTnT: Tropomyosin binding

11
Q

Advantages of measuring troponins for MI

A

early marker and long term marker

DISADVANTAGE: Can mask a small recurrent MI

12
Q

Advantages of measuring CK-MB for MI

A

Early increase

Sharp peak after 1 day (Wouldn’t mask small recurrent MI)

13
Q

Liver injury effects

Function tests

Membrane integrity tests

Hepatitis

A

-Leads to loss of function/leaky membranes

Function tests:

  • Ammonium (High)
  • Albumin (Reduced)
  • Bilirubin (High)

Integrity Tests:

1) Alanine aminotransferase (ALT)
- Not specific for liver
- High concentration in hepatocytes

2) Aspartate aminotransferase (AST)
- High concentrations in liver and heart

Hepatitis:
-ALT > AST

14
Q

Bile obstruction:

Types

A

Extra-hepatic:

  • Bile ducts obstructed
  • Ex: Gallstones, tumors

Instra-hepatic:
-Bile ducts irritated in liver cirrhosis

15
Q

Alcohol Liver disease

A

-AST, ALT, GGT elevated
(Aspartate aminotransferase, Alanine aminotransferase, y-glutamyl transferase)
-2:1 ratio of AST/ALT or higher

(can be seen in liver cirrhosis)

16
Q

Pancreatisis

Acute

Chronic

A

Acute:
-Gallstone blockage = increase of serum amylase, (pancreatic) lipase, ALP, and GGP (greater than 2-lipase/amylase)

Chronic:

  • Cystic Fibrosis (CF)
  • Hyperlipidemia
  • years of abuse
  • Shows less increase in serum
17
Q

Alkaline Phosphatase

Where?

Normal increase

Abnormal increase?

A

Bone, bile ducts, placenta, intestines

Normal increase
= bone growth, natural healing of bones, pregnancy

Abnormal increase
=Paget disease, bone tumors

18
Q

Prostate cancer

Liver cancer

(tests_

A

Prostate cancer test:
-Specific antigen test

Liver Cancer test:
-Alpha fetoprotein (Normal in fetus’s, but indicated

19
Q

How to measure acute MI

A

-Measure Cardiac troponins (cTnI or cTnT) and CK-MB

INCREASE indicates acute MI

20
Q

When does myoglobin and CK isoforms peak after an MI injury?

A

-Immediately (First one to peak), but short lasting

21
Q

Noncompetitive Enzymes

A

Same KM, decreases VMAX

22
Q

Allosteric enzyme and curves

A

-Activators = feed fwd = shift to LEFT on graph = smaller .5 km = more affinity for substrate

Feedback-Inhibitor = Shifted to the RIGHT =
leading to a larger K 0.5 = less affinity for the substrate.

SIGMODIAL CURVE