Clin chem enzyme

γ-Glutamyl transferase

If the objective is to measure the enzyme activity, where on the initial velocity versus substrate concentration plot should the substrate concentration be fixed at?

Zero-order phase

The Lineweaver-Burk plot of an enzyme that follows the Michaelis-Menten model produces

????/

What is the correct order for the rate of production formation in an enzyme-catalyzed reaction?

Lag, linear, substrate depletion

Which is the correct description of the structure of enzymes?

quaternary: two or more peptide subunits

How do enzymes increase the reaction rate?

They lower the activation energy for the enzyme–substrate complex.

A Lineweaver-Burke plot that shows an unchanging y-intercept but has an increased slope is an example of

competitive inhibition.

Which of these statements about enzymes is TRUE?

Ezymes are not altered or consumed during the reaction

Which of the following would NOT show an increase in alkaline phosphatase?

Hemolytic anemia

Which of these enzyme methodologies uses the same reaction as the LD method?

ALT

Malate dehydrogenase (MD) is used in the aspartate transferase reaction mixture to convert:

 

Oxaloacetate to L-malate.

The Wroblewski and LaDue method uses the _____ to ______ reaction

pyruvate & lactate

Mrs Jones passed out at work and CPR had to be performed. CPR was sucessfull and she is now being assessed by the ER physician. Which one of these CK fractions should be ER physician expect to be elevated?

CK-MB

Zero order kinetics results:

 

When all of the available sites on the enzyme are saturated with substrate.

Which of the following are the most common cause(s) of acute pancreatitis?

 

A and C

Mrs. Smith has the following chemistry results:
CK: moderately increased
LD: moderately increased

The probable diagnosis is:

 

Myocardial infarction.

Which of these enzyme methodologies uses the Karmen method?

AST

Board Review Question: Aminotransferase enzymes catalyze the

 

exchange of amino and keto groups between alpha-amino and alpha-keto acids

Board Review Question:  The most specific enzyme test for acute pancreatitis is:

lipase

Board Review Question:  A serum sample drawn in the emergency department from a 42 year old man yielded the following laboratory results:

• CK 185IU/L (normal = 15-160)

• AST 123 IU/L (normal = 0-48)

• CK-MB 6 IU/L (normal = 2-12)

Which of the following conditions might account for these values?

 

crush injury in the thigh 

Board Review Question:  The presence of which of the following isoenzymes indicates acute myocardial damage? 

 

CK-MB

Board Review Question:  Which of the following is a characteristic shared by lactate dehydrogenase, malate dehydrogenase, isocitrate dehydrogenase, and hydroxybutyrate dehydrogenase? 

 

they catalyze oxidation-reduction reactions 

Board Review Question:  Which of the following enzymes catalyzes the conversion of starch to glucose and maltose?

amylase

Board Review Question:  In the assay of LDH, which of the following products is actually measured?

NADH

Board Review Question: Which two conditions can "physiologically" elevate serum alkaline phosphatase?

 

growth, third-trimester pregnancy

A Lineweaver-Burke plot that shows an unchanging y-intercept but has an increased slope is an example of

 

competitive inhibition.

Which method is not routinely used for isoenzyme determination?

 

Mass spectrometry

Which of the following is false regarding an enzyme assay?

 

The direction of the assay is always what occurs in human physiology.

Which one of these factors can affect enzyme function

 

all of the above

Serum lipase catalyzes:

 

Hydrolysis of triglyceride to fatty acids and glycerol.

Which of these enzyme methodologies uses the Bowers and McComb method?

ALP

A substrate used in lipase reactions is:

 

Olive oil emulsion.

Which of these statements about enzymes is TRUE?

 

Ezymes are not altered or consumed during the reaction

Which of these enzyme methodologies uses the same reaction as the LD method?

ALT

Serum chemistry results on a 53-year-old female are
AST: 120 U/L (4-34U/L)
ALT: 185 U/L (5-40 U/L)
ALP: 785 U/L (<165 U/L)
GGT: 225 U/L (5-24 U/L)
Total Bilirubin: 10.8 mg/dL
Direct Bilirubin: 8.6 mg/dL
urine bilirubin: positive
urine urobilinogen: Normal
fecal urobilinogen: decreased
These results are consistent with a diagnosis of:

 

Biliary obstruction.

Board Review Question: Which of the following enzymes are used in the diagnosis of acute pancreatitis?

 

AMY and LIP

Board Review Question: A physician suspects hos patient has pancreatitis. Which test(s) would be the most indicative of this disease?

amylase

Board Review Question: AST is characteristically elevated in disease of the

liver

Board Review Question:  The protein portion of an enzyme complex is called 

apoenzyme

Board Review Question:  Which of the following chemical determinations may be of help in establishing the presence of seminal fluid?

 

acid phosphatase 

Board Review Question:  The most heat-labile fraction of alkaline phosphatase is obtained from 

bone

Board Review Question: The greatest activities of serum AST and ALT are seen in

 

acute hepatitis

Which term refers to a cofactor that is needed for optimum enzyme activity and is a tightly bound nonprotein molecule?

 

prosthetic group

How do enzymes increase the reaction rate?

 

They lower the activation energy for the enzyme–substrate complex.

What is the typical unit of measure for enzymes?

 

IU/L

A Lineweaver-Burke plot that shows an unchanging y-intercept but has an increased slope is an example of

 

competitive inhibition.

Glucose oxidase, an enzyme used in measuring glucose is an example of

 

oxidoreductase.

When plotting initial velocity versus substrate concentration, during which phase is the rate increased with increasing substrate concentration?

 

First-order phase

The highest levels of alkaline phosphatase are seen in:

 

Obstructive liver disease.

In noncompetitive inhibition

 

the inhibitor binds to an allosteric site and changes the shape of the enzyme, altering the active site

Aspartate aminotransferase is elevated in diseases involving the:

 

Heart muscle.

Many enzymes in the blood plasma show maximum activity in which of the following pH ranges?

 

7 to 8

Levels of this enzyme are useful in the diagnosis of a genetic defect, which leads to increased apnea (difficulty breathing) after surgery using succinyl choline.

Cholinesterase

The indicator reaction (what is actually measured) in Oliver-Rosalki is:

 

The reduction of NADP⁺.

Zero order kinetics results:

When all of the available sites on the enzyme are saturated with substrate.

Board Review Question: The most sensitive enzymatic indicator for liver damage from ethanol intake is

 

gamma-glutamyl-transferase (GGT)

Board Review Question: Given the following results:

• ALP: marked increase

• ALT: slight increase

• AST: slight increase

• GGT marked increase

This is most consistent with

 

obstructive jaundice

Board Review Question: In which of the following conditions would a normal level of creatine kinase be found?

hepatitis 

Board Review Question:  The enzyme present in almost all tissues that may be separated by electrophoresis into five components is 

 

lactate dehydrogenase