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Flashcards in C13 Enzymes Deck (70):
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Enzymes

Special group of catalysts that are made up of proteins, speed up reaction

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How are enzymes measured?

Activity

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Catalyst

substances that lessen the amount of energy required for chemical reactions to occur

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Enzyme (structure) Primary

amino acid sequence

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Enzyme (Structure) Secondary

interaction between 2 locations on protein chain

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Enzyme (structure) Tertiary

folding of chains (3D structure)

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Enzyme (structure) Quadernary

2 or more separate polypeptide chains

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Active site

physical location on the enzyme molecule which interacts w/ substrate molecule

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Allosteric site

non active site, but which may interact w/ other substances to change overall enzyme 3D shape

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Isoenzyme

structurally diff enzymes (proteins) but which catalyze the same chemical reactions

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Cofactor

a non protein substance required for normal enzyme activity, maintain enzyme 3D structure, critical for enzyme function

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2 types of cofactors?

activators (inorganic) & coenzyme (organic)

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Holoenzyme

Enzyme+coenzyme (prosthetic group)=active enzyme

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Proenzyme

enzyme-coenzyme=active enzyme

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The amount of energy required to stimulate molecules to break their chemical bonds and form new bonds is the ___.

activation energy

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absolute type enzymes

catalyzes only 1 specific substrate

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Group type enzymes

catalyzes reactions of a particular chemical group

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Bond type enzyme

catalyzes reactions of particular chemical bonds

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Steroisomerism

catalyzes reactions of steroisomers

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What does the substrate do?

saturates enzymes (all enzymes react with excess substrate)

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Enzyme activity

the rate at which an enzyme catalyzes a chemical reaction

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Why is activity measured under Zero Order conditions?

because this is where the reaction rate is dependent on the work (activity) of the enzyme

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Competitive inhibitors

substances that bind at the enzyme's site, competes with substrate for the active site, addition of additional substrate increases the reaction rate

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Non-competitive inhibitors

substances that bind at an enzyme's non-active site, enzyme 3d shape is altered, decreasing enzyme activity, may bind substrate but additional substrate has no effect

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uncompetitive inhibitor

substances that bind with enzyme-substrate complex

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How can enzyme activity be measured?

increase of product, decrease of substrate, decrease of co-enzymes, and increase of altered co-enzyme

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Fixed-Time Assay

substrate concentration is measured at set time intervals to determine enzyme activity

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What is a slight delay from the beginning of the reaction to max velocity?

lag phase

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substrate depletion

extreme elevations in enzyme activity may deplete the substrate between measured intervals, causes falsely decreased activity results

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Multipoint Continuous Monitoring (Kinetic Assay)

continuous measurements of substrate-product concentration are recorded by the spectrophotometer of an automated analyzer

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What is the common unit of enzyme activity?

International Unit (IU)

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1 IU

that amount of enzyme that will convert 1 micro-mole of substrate to product per minute under defined conditions

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NADH

Common co-enzyme, absorbs light at 340 NM

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Why are enzymes used as reagents?

to measure other non-enzymes

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High concentrations of CPK are found in?

muscle, cardiac & brain tissues

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Increased CPK is associated with?

damage to the muscle, cardiac, and brain tissues

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Increased CPK is useful to diagnose?

AMIs and skeletal muscle disease (muscular dystrophy)

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How many isoenzymes does CPK have?

3

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CK-BB

Brain

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CK-MB

Cardiac

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CK-MM

Skeletal muscle

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Because of CK-MBs association with cardiac tissue, increased CPK-MB (>_6% Total CPK activity) is a strong indication of?

AMI

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Lactate dehydrogenase is found in what tissues?

skeletal muscle, cardiac muscle, renal tissue, and RBCs

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Plasma LDH is elevated in what conditions?

Liver disease, cancers, AMI, hemolytic diseases

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How many isoenzymes does LDH have?

5

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LD-1

(HHHH) Cardiac, RBCs

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LD-2

(HHHM)

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LD-3

(HHMM) lung, spleen, pancreas

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LD-4

(HMMM) hepatic, skeletal

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LD-5

(MMMM)

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Aspartate aminotransferase high concentrations are found in?

skeletal muscle, cardiac muscle, liver tissue, and lung tissue

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Alanine aminotransferase has the highest activity in the?

liver

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alkaline phosphate does what?

removes phosphates from organic compounds

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alkaline phosphate has higher concentrations in?

bone and liver

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what group of people have higher ranges of alkaline phosphate?

children, because they are still growing

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Amylase catalyzes breakdown of?

starch and glycogen to glucose

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High concentrations of amylase are found in?

pancreas and saliva

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amylase is filtered into the?

urine

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increased plasma or urine amylase is very sugguestive of?

pancreatitis or pacreatic malignancy

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Gamma glutamyltransferase has high concentrations in the?

liver

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increased plasma GGT is associated with?

hepatobiliary disease & alcoholic cirrhosis

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Lipase hydrolyzes (break down)?

fat

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high concentrations of lipase are found in?

pancreas

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pseudocholinesterase is considered a screening test for exposure to?

organophosphate exposure (pesticides)

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3 step in diagnosing AMI?

1-symptoms, physical exam, patient history
2-EKG
3-lab tests

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Myoglobin is a soluble?

heme protein

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two forms of Troponin?

Troponin I and Troponin T

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Cardiac enzymes, "CAL 911"

CPK, AST, LDH

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What is the "triage" used for?

common commercial test package that quantitates the 3 most significant lab markers for AMI: CK-MB, Troponin I, and Myoglobin

70

How are enyzmes measured?

At Zero Order