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114 Cards in this Set

  • Front
  • Back

Enzymes

Protein catalysts produced by living cells

Enzymes are produced by?

All living cells

Enzymes do what to chemical reactions?

Speed up

Catalyst

Any chemical that speeds up a reaction

Substrate is

The reactant/chemical the enzyme is going to act upon

Major influence on enzyme reactions

Substrate concentration

Michaelis and Menten hypothesized the role of substrate concentration in formation of

Enzyme substrate complex

Substrate readily binds to free enzyme at

A low substrate concentration

When the amount of enzyme exceeds the amount of substrate, the reaction

Steadily increases as more substrate is added

Stereo-enzymes

work on only one steoisomer but not the other steoisomer

Stereo-enzymes

work on only one stereoisomer but not the other stereoisomer

Enzymes cause what with reactions?

Causes reactions to proceed at a much faster rate by lowering the energy of activation

Active site/binding site

areas of the enzyme where the substrate attaches and where the reaction takes place

Substrate must fit into sites...

exactly

Lock and key theory for substrates

Lock - Enzyme


Key- Substrate

Apoenzyme (protein) + cofactor (non-protein helper) ---------------->

Holoenzyme

activator

inorganic ions Ca2+ Mg2+ Zn2+ Cl-1


Minerals (charged ions)

Coenzyme

Organic compount, vitamin B family, riboflavin is B2

Coenzyme

Organic compound, vitamin B family, riboflavin is B2

activator =

some enzymes need metal/nonmetal ions for the enzyme to work

Coenzyme- what is necessary for certain enzymes to work?

Organic molecules

Examples of coenzymes

NAD, NADP (loosely bound to enzyme)

Prosthetic group

Organic portion that is tightly bound to the apoenzyme or protein portion

Proenzyme

the inactive precursor of the enzyme.

Example of proenzyme

Pepsinogen is precursor to pepsin

Another example of proenzyme

clotting factors

Proenzymes are for

protection

Isoenzymes

different forms of the same enzyme, unique to certain organs

Isoenzymes

different forms of the same enzyme, unique to certain organs

Examples of Isoenzymes

LDH, ALP, CPK, ACP

Isoenzymes can be separated by

heat sensitivity, chemical inhibition, immunassay, chromtaography

What does Immunassays use

antibodies and electrophoresis

CK or CPK is rich in

heart muscle and skeletal muscle

Isoenzyme structure of CK (Creatine kinase) or CPK (C Phosoho kinase) : CK1

CK1 = BB



Isoenzyme structure of CK (Creatine kinase) or CPK (C Phosoho kinase) : CK2

CK2 = MB

Isoenzyme structure of CK (Creatine kinase) or CPK (C Phosoho kinase) : CK3

CK3 = MM

CK2 can be found in

the heart

CK3 can be found in

Skeletal muscle

LD isoenzymes : LD1

LD1 = HHHH

LD isoenzymes : LD2

LD2 = HHHM

LD isoenzymes: LD3

LD3 = HHMM

LD isoenzymes: LD4

LD4 = HMMM

LD isoenzymes: LD5

LD5 = MMMM





Enzymes that transfer hydrogens, oxygen, or electrons from one molecule to another molecule

Oxidoreductase

Group of atoms from one molecule to another molecule (dehydrogenase) LD (Lactate dehydrogenase)

Transferase

Digestive enzymes from one to another

Hydrolase

Enzyme that breaks down molecules w/o using water

Lyase

Enzyme that changes L forms of a molecule to a D form

Isomerase

Ligase

Enzyme that joins 2 molecules and forms one molecule

ALP pH

9.8 or 10

ALP pH

9.8 or 10

GAMMA GTP or GAMMA GT OR GGTP

Gamma glutamyl Transpeptidase

GGTP comes from

The liver and hepatobiliary system

No GGTP comes from

Human heart muscle or skeletal muscle

GGTP is specific for

Iiver

GGTP more sensitive to what disorders in liver

Cholestasis and obstructive jaundice

GGTP is VERY SENSITIVE TO

Alcohol abuse - used to monitor alcholism

ALP ( BONE ENZYME)

Alkaline phosphatase

Alkaline phosphatase found in BLIP

Bone, liver, intestine, placenta

Optimum reaction pH for alkaline phosphatase

9.7 or 9.8 or 10

Alkaline phosphatase is found mainly in

Bone and liver

Alkaline phosphatase is higher in

Children because of its important part in bone formation

Alkaline phosphatase is increased in what bone disease

Paget's disease and rickets

Alkaline phosphatase is also increased in

Liver disease

Preferred substrate for measuring alkaline phosphatase

P nitrophenol phosphate

Alkaline phosphatase is stable for how many hours at room temperature?

8 hours

Alkaline phosphatase is stable for how long frozen?

1 week at 4 degrees Celsius;one month Frozen

Heat differential test for Alp of bone liver and placental origin

Liver is stable at 56 degrees, bone is labile at 56 degrees, placenta is stable at 65 degrees

Muscle enzymes

CK, AST, and aldolase

Aldolase is only found in

Muscle

Pancreatic enzymes include

Amylase and lipase

Which pancreatic enzyme is more specific and which is sensitive?

Amylase is more sensitive and lipase is more specific

Function of amylase

Hydrolyzes starches (polysaccharides) into small molecules maltose and glucose

Amylase is important in the digestion of

Carbohydrates

Amylase is present in

Salivary glands and pancreas

Serum concentration of amylase will be what an acute pancreatitis

Increased

Why would a physician become interested in amylase?

Because pancreatitis does not involve a need for operation

What factors can affect the measurement of amylase

Anticoagulants that bind calcium, chloride ions, must use saline. Fluoride, avoid gray top tubes, saliva

How long is amylase stable

For a week at room temperature

What is the optimum pH for amylase?

7.0

Alpha amylase prefers the 1.4 linkages ______ not _____ (1.6 linkages)

Amylose not amylopectin

Methods of measuring amylase: Saccharoogenic method

Involves measurement of reducing sugars hydrolyzed from polysaccharides. Most accurate

Amyloclastic method

Measures the change in the physical property of starch. Starch is the substrate and measures the staining property (using iodine) rate of disappearance measured by reaction with starch (blue color) rate of disappearance is proportional to amylase concentration

Kinetic method (starch)

Involves 4 to 5 reactions using NAD+NADH

Amylase is the only plasma enzyme that is found in the

Urine

Amylase has a low molecular weight that can be cleared by the

Kidney

Amylase can remain elevated in the urine for

7 to 10 days

In serum, amylase is elevated for

2-3 days

Lipase

Unique enzyme that works on the surface area of fats

Lipase ONLY comes from

Pancreas

Lipase parellels amylase but....

Remains elevated longer in acute pancreatitis.

Lipase peaks...

At 72 to 96 hours and remains elevated for several days (declines)

Substrate for lipase

Olive oil

Pure reagent form of triglycerides

Glycerol and 3 fatty acids

Classic method for triglyceride measurement

Cherry Crandall hydrolysis of olive oil and titration of free fatty acids using dilute sodium hydroxide

Teitz methods

24 hr incubation

Cherry method

6 hour incubation


Turbidimetric method for lipase

Measures reduction of turbidity

Trypsin

Also synthesized in the acne cells of the pancreas as proenzyme trypsinogen

Trypsin is elevated in ____ and aids in diagnosis of ______ and _____

Pancreatic non function;fibrocystic disease

In cystic fibrosis there is a _____ in the secretion of trypsin by the pancreas

Decrease

Specimens for trypsin measurement

Aspiration of duodenal fluid or fresh feces

Normal values for stool (trypsin)

Infants <1yr 1:80 older children 1:20/1:40 fibrocystic pts 1:32/64

Normal values for duodenal fluids (trypsin)

Infants 1:32/64 or > fibrocystic patients <1:4

CPK rises within ____. Peaks _____ and returns to normal ______

4-6 hours after onset of pain, 24-36 hours, in 3 days

Pseudocholinesterase

Insecticide (organophosphate) poisoning is the clinical significance.

Enzymes in rbcs are measured for this by

Enzyme inhibition and the inhibition is proportional to the amount of exposure to the insecticide

method - trypsin by x-ray film

fresh stool specimen diluted with saline for 1:5 to 1:320. Each dilutionis dropped on old unexposed x-ray film along with controls.

x-ray film technique: Incubated for

30 minutes at 37 degrees.

Prostatic enzymes: acid phosphatase

group of related enzymes found in the liver, spleen, milk, rbcs, platelets, bone marrow, and prostate gland.

How much of the acid phosphatase comes from the prostate

1/3 to 1/2

Optimum ph for acid phosphatase

5.0

Prostatic specific antigen (PSA) is a

glycoprotein only produced by the prostate gland and is now used to screen for prostatic cancer.

Serum determinated is usually requested for diagnosis of _______ ________ with ______

prostatic carcinoma; acid phosphatase