Test3 Flashcards
What is a substrate?
Substance that the catalyst binds with. Each enzyme will catalyze with 1-2 substrates
What are isoenzymes?
Enzymes that serve the same purpose but are found in different places or have different structures
What are zymogens?
Inactive enzymes (ie- pepsinogen)
What are the 5 main characteristics of enzymes?
Effective in small amounts
Unchanged in reaction
Affect speed of reactions but not levels of reactants
High specificity
Organic catalysts
What are allosteric sites?
Site separate from active site that will inhibit or activate active site
What are cofactors?
Non protein molecules that are necessary to complete reaction. Used in process, usually
When bound to enzyme, called prosthetic group
Why are cofactors important? How does it affect samples?
Cofactors bing to active site to complete shape.
EDTA, oxalates, citrates, and fluoride will chelate with common cofactors (serum has none of this)
Why do we want to measure enzymes in blood?
Enzymes exist in cells, if present in blood, indicates damaged cells.
Increased cell amount call also cause enzyme increase
Enzymes are large so they stay in blood for a long time
What are the street main things we can determine from enzyme blood levels?
Where is the problem?
How severe?
Is patient recovering?
What are the main traits of isoenzymes?
Each has different substrate/cofactors affinity
React differently to inhibitors
Differ in physical properties (charge, amino acids)
Different immunological
Same molecule size
What are the 6 things that must be controlled during enzyme testing?
Ph
Temp
Substrate concentration
Time
Activators
Inhibitors
Do we measure enzyme concentration?
No. We measure activity of a substrate (increase of product or decrease in substrate)
What is the International Unit of Enzyme Activity?
Under Very specific conditions, defined as quantity of enzyme that catalyzes the reaction of 1 micromole of substrate/min
Appears at U/L
Why are enzymes used as reagents?
Measure true level of substrate due to high specificity
Requirements for blood samples for enzyme measurement
- serum not plasma (heparin sometimes acceptable)
Avoid hemolysis
Maintain proper storage
Use deionized water (WHY)
Two types of enzyme test
Manual/endpoint
Kinetic
Manual/endpoint enzyme test-
Allow enzyme to catalyze for specific amount of time, stop reaction, introduce colour changing reagent
Colour produced is directly proportional to product
What are enzymes?
Known markers of cellular disease and death
Used as reagents within test systems (both specific to clinical chem)
