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Enzymes and Protein Isoforms
68K 12-01 Chem 101 Unit 5
107
Chemistry
Undergraduate 1
12/01/2011

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Term
Enzyme
Definition
proteins that are catalysts of biochemical reactions.
Term
Substrate
Definition
reactant that binds to enzyme and is converted to product
Term
Product
Definition
final molecule resulting from reaction
Term
reaction rate
Definition
amount of product produced per unit of time
Term
Active site
Definition
region of the enzyme where the substrate binds.
Term
Apoenzyme
Definition
requires an additional non protein prosthetic group to function
Term
cofactor
Definition
ions or smaller organic molecules needed for the activity of specific enzymes (non-protein)
Term
Coenzyme
Definition
organic molecules derived from niacin, riboflavin and other vitamins. needed for activity of specific enzymes. (non-protein)
Term
Holoenzyme
Definition
complete enyme-cofactor complex
Term
Inhibitor
Definition
reduce catalytic activity of an enzyme
Term
Zymogen
Definition
inactive enzyme precursor
Term
Isoenzyme
Definition
structurally related protein products of different genes that catalyze the same reaction
Term
Coupled Reaction
Definition
reactions that share a common intermediate
Term
Enzyme Properties
Definition
Biological Catalysts
High Substrate Specificity
Term
Lock and Key Theory
Definition
based upon the moleculare shape of the enzyme active site and substrate. If they match, reaction will occur
Term
Induced Fit Model
Definition
enzyme reacts with the substrate causing changes in the configuration of the active site, allowing them to fit together and reaction to occur
Term
Transfer (transferase)
Definition
catalyzes the transfer of groups, not including hydrogen
Term
Redox (Oxidoreductase)
Definition
catalyze oxidation/reduction reactions
Term
Hydrolytic (hydrolase)
Definition
catalyze hydrolysis reactions
Term
Ligase
Definition
catalyzes the covalent bond of two molecules coupled with the hydrolysis ATP bonds
Term
Isomerase
Definition
catalyzes the interconversion of structures or geotric changes in a molecule
Term
Lyase
Definition
Catalyzes the formation of double bonds
Term
Common Digestive Enzymes
Definition
Amylase, lipase, bile salts, peptidases, sodium bicarbonate
Term
Amylase
Definition
digests startches to disaccharides
Term
lipase
Definition
further digests dietary fats into fatty acids and gylcerol
Term
bile salts
Definition
involved in the emulsification process of lipid absorbtion
Term
Peptidases
Definition
break specific bonds (limited proteolysis) or break down complete peptide (unlimited proteolysis)
Term
Pepsin
Definition
begins digesting of proteins by hydrolyzing them to smaller polypeptides
Term
Trypsinogen
Definition
converted into trypsin. digests polypeptides into smaller amino acids
Term
Sodium Bicarbonate
Definition
alkaline secretion that neurailizes tummy juice as it enters the small intestine.
Term
Competitive Inhibitors
Definition
directly compete with the substrate for binding with the active site
Term
noncompetitive inhibitors
Definition
weakly bind to an allosteric regulatory site on the enzyme. Do not compete with substrate.
Term
Bilirubin
Definition
principle pigment in bile derived from the breakdown of hemoglobin
Term
cirrhosis
Definition
abnormal structure and function of the liver. caused by liver disease.
Term
excretory
Definition
discharge of waste from organ
Term
secretory
Definition
process by which substances are released from an organ for a particular purpose
Term
Hepatitis
Definition
inflammation of the liver
Term
Jaundice
Definition
yellowish staining of the skin and sclerae, caused by high levels of bilirubin
Term
NEcrosis
Definition
death of living cells or tissues
Term
REticuloendothelial System (RES)
Definition
cels that can take up and sequester inert particles and vital dyes, includes macrophage and precursors.
Term
Lobules
Definition
hexagonal plates of cuboidal hepatic cells, microscopin functional unit of the liver
Term
Sinusoids
Definition
represent the main blood supply to the liver, located between the plates of hepatic cells.
Term
Kupffer Cells
Definition
phagocytic cells, line the sinusoids, remove bacteria and other foreign particles from the blood.
Term
Canaliculi
Definition
interlobular bile ducts,
Term
Biliary Tract
Definition
network of ducts that connect the liver, gallbladder and duodenum
Term
Hepatic Bile Duct
Definition
receives bile from the canaliculi, where bile exits the liver.
Term
Cystic Ducts
Definition
ducts that deliver bile from the gallbladder
Term
Common bile duct
Definition
delivers bile to the duodenum which aids in digestion
Term
Portal Vein
Definition
delivers blood rich in digestive end products to the liver. 2/3 of the hepatic blood supply
Term
Hepatic Artery
Definition
delivers oxygen rich blood to the liver. 1/2 of the livers blood supply
Term
Hepatic Vein
Definition
blood exits the liver.
Term
Functions of the liver
Definition
Excretory
Metabolism & Storage
Detoxification
Filtration
Term
Excretory Function of the Liver
Definition
excretes bilirubin, cholesterol and drugs
Term
Metabolism Function of the Liver
Definition
Liver metabolises and stores lipids, proteins, vitamins and minerals.
Term
Dextoxification Function of the Liver
Definition
liver converts toxic and relatively insoluable compounds into less toxic compounds
Term
Filtration Function of the Liver
Definition
the Kupffer cells remove bacteria and particles from the blood.
Term
FActors that Influence REaction RAtes
Definition
Enzyme concentration, substrate concentration, preneces of conenzymes/cofactors, temperature, PH, inhibitors, organic solvents, salt concentration
Term
Enzyme Concentration affects reaction rate...
Definition
increased products per time as enzymes increase
Term
Substrate concentration affects reaction rate...
Definition
exymes works at max velocity when enzyme concentration is directly proportional to substrate concentration
Term
Temperature affects reaction rate...
Definition
increasing temps usually increases reaction rate. Molecules move faster.
Term
pH affects reaction rate...
Definition
other than optimal pH values, enzyme activity is affected because of structure alterations
Term
ORganic Solvents
Definition
cause proteins to denture by disrupting hydrogen bonds
Term
Allosteric Enzyme
Definition
has both an active site and an allosteric site to which effectors can bind. effectors binding causes the active site to change.
Term
NEgative Allosterism
Definition
loss or reduction of product of the enzyme
Term
Positive allosterism
Definition
additional product generated
Term
Feedback Inhibition
Definition
frequently occurs in metabolic pathways. Excess final product binds to an earlier enzyme and inactivates it.
Term
Protein Modification
Definition
Chemical groups are added or removed. can activate or inactivate the enzyme. Seen with phosphorylation
Term
Testing Methodology for Aspartate Aminotransferase (AST)
Definition
Enzymatic Reaction. Spectrophotmetrically measured at 340 nm over time. Nad+ is directional proportional to AST
Term
Specimen requirements for AST
Definition
serum, non hemolyzed, fasting, free of lipemia
Term
Testing MEthod for Alanine Aminotransferase (ALT)
Definition
enzymatic reaction, spectrophotometricly measured at 340nm over time, to measure NADH which is directly proportional to ALT.
Term
Specimen Requirements for ALT
Definition
Serum, fasting specimen, non hemolyzed, free of lipemia
Term
Testing Method fro Gamma-glutamyltransferase (GGT)
Definition
Enzymatic Analysis. Gycerin is added, the product p-nitroaniline is measured at 405nm and 37C
Term
Speciment requirements for GGT
Definition
Fasting speciment, non hemolyzed, free of lipemia, serum.
Term
Testing Method for Alkaline Phosphatase (ALP)
Definition
Enzymatic analysis. The production of nitorphenoxide is spectrophotometrically measure at 405 nm.
Term
Specimen Requirements for ALP
Definition
Serum, fasting, non hemolyzed, free of lipemia
Term
All Testing Methods of Bilirubin
Definition
Modifed Evelyn-Malloy Method
Jendrassik and Grof Method
Direct Spectrophotmetry
Term
Specimen requirements for Bilirubin
Definition
fasting, non hemolyzed, free of lipemia, protect from light.
Term
Modified Evely-Malloy Method
Definition
Diazo reagent added to measure conjugated bilirubin at 540nm.
Methanol reagent added to develop unconjugated bilirubin, total protein thein measured at 540 nm.
very susceptible to hemolysis
Term
Jendrassik and Grof MEthod
Definition
Most commonly used method. Sodium benzoate, followed by diazotized sulfanilic acid are incubate with the sample, then ascorbic acid, alkaline titrate, and dilute HCl are added, the resulting blue azobilirubin is measure at 600 nm.
Term
Direct Spectrophotometry (Neonatal Bilirubin)
Definition
Limited to infants because of strong interference in older children and adults, measured at 454nm, then the easurement at 540nm is subtracted to account for Hb.
Term
Function of AST
Definition
Catalyzes the transfer of an amino group or amino acid between aspartate and alpho-keto acids.
Term
Sources of AST
Definition
Primary: Liver and heart
Secondary: skeletal muscle, kidney, pancreas
Term
Clinical Significance of AST
Definition
widely used in identifying necrosis and inflammation of the liver. It elevates rapidly at the beginning of the disease.
Term
Elevated EST is seen in:
Definition
Chronic Hepatitis
Cirrhotic Liver
Muscular dystrophry, dermatomyositis, and pulmonary emboli
Acute pancreatitis, crash injuries, gangrene, hemolytic disease
Term
Function of ALT
Definition
catalyzes the reversile transfer of an amine group from the amino acids alanine and glutamate to alpha-ketoglutarate and pyruvate.
Term
Sources of ALT
Definition
widely distributed through the body, liver is the main source, also concentrated in the kidney
Term
Clinical Significance of ALT
Definition
more useful than AST in viral hepatitits and cholestatic disease, increases rapidly during hepatitis 15 to 20 times, used to screen blood donars for viral hepatitis.
Term
Function of GGT
Definition
aids in the transport of amino acids through cell membranes, and involved in glutathione metabolism
Term
Sources of GGT
Definition
liver and renal tubules highest activity, has been found in other places.
Term
Clinical Significance of GGT
Definition
elevated in all liver diseases, highest concentration from biliary obstructions, primary or secondary liver cancers, extremely sensitive, non specific, used as a screentest for alcohol abuse.
Term
Function of ALP
Definition
associated with bone calcification and lipid transport
Term
Sources of ALP
Definition
Main source: Liver and Bone
Secondary: Spleen, Kidney, Intestines,
Term
Clinical Significance of ALP
Definition
To detect hepatobiliary disease, liver responds by synthesis of ALP, Bone disease shows the highest levels.
Term
Ammonia
Definition
toxic compound, normally formed in the body from the breakdown of proteins
Term
Clinical Significance of NH3 Levels
Definition
dx of Reye's syndrome, increases are caused by the liver's inability to metabolize ammonia. can cause decreased mental capacity, stupor, coma, death
Term
Bilirubin clinical significance
Definition
increase can cause jaundice
can also indicate Gilbert's and Grigler-Najjar syndromes
Term
Jaundice
Definition
yellow discoloration of the plasma, skin, and mucous membranes caused by high concentrations of bilirubin
Term
Physiologic Jaundice
Definition
Most common hyperbilirubinemia, unconjugated common in neonate, levels greater than 18-20mg can cause brain damage, also caused by hemolytic anemias.
Term
Hepatic Jaundice
Definition
conjugated and unconjugated bilirubin
usually due to a defect in bilirubin transport to the liver.
Term
Posthepatic Jaundice
Definition
conjugated hyperbilirubinemia, impaired excretion, caused by obstruction of bile fulow to the intestines due to gallstones or tumor in the bile duct.
Term
Cirrhosis
Definition
caused by excessive hepatic damage. irreversible scarring with formation of fibrotic connective tissue. Loss of functioning liver cells and impaired blood flow.
Term
Hepatitis
Definition
inflammation of the liver caused by infections, radiation, drugs, chemicals or toxins
Term
Hep A
Definition
transmitted by fecal-oral route by contaminated food or water.
Term
Hep B
Definition
transmitted by blood, body fluids, and sexual routes.
Term
HEpatic Tumors
Definition
cancers tumors from the liver, often associated with cirrhosis or Hep B
Term
Ethanol
Definition
the most abused drug that affects the liver, leading cause of cirrhosis in the US
Term
Acetiminophen
Definition
large doses produce fatal hepatic necrosis unles rapid treatment occurs
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