IMS 4- enzymes
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- Created by: Ettie Conway
- Created on: 11-04-24 10:12
which statement is not true?
Increase the rate at which the reaction equilibrium is reached, by shifting the position of equilibrium
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equilibrium
forward and reverse reaction rates are equal
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equilibrium constant K =
[B]/[A]
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which is not a way that enzymes decrease Ea
by increasing the temperature of the reactants such that they are optimised for the reaction;
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active site bonds to substrates via
multiple weak interactions
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E + S -->(k1) <--(k2) ES --> (k3) E + P
what is this method called?
what is this method called?
michaelis-menton model
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E + S --> <-- ES --> E + P
what is K1?
what is K1?
the rate constant of formation enzyme-substrate complex from enzyme and substrate
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E + S --> <-- ES --> E + P
what is K2?
what is K2?
the rate constant of dissociation of ES complex into enzyme + substrate
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E + S --> <-- ES --> E + P
what is K3?
what is K3?
the rate constant of dissociation of ES complex into enzyme + product
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michaelis constant (km) =
K2 + K3/ K1
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michaelis menten model largest assumption
K3 << K2
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Michaelis- menten equation?
v= vmax X [s]/ ([s] + Km)
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michaelis menton equation in y= mx+c form
1/v = (km/Vmax X 1/[s]) + 1/Vmax
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what drug is this?
Covalent modification of a serine residue in the active site
Inhibitor binding is competitive, inhibition is irreversible
Covalent modification of a serine residue in the active site
Inhibitor binding is competitive, inhibition is irreversible
aspirin
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what drug is this?
Binds to active site, but not covalently attached
Inhibitor binding is competitive, inhibition is reversible
Binds to active site, but not covalently attached
Inhibitor binding is competitive, inhibition is reversible
ibuprofen
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ibuprofen binds to ?
cyclooxygenase-1 (COX-1)
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what metal ion in carbonic anhydrase binds with H2O and activates it for reaction with CO2?
Zn2+
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which metal ion is used in kinases?
mg2+
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which metal ions act as redox agents in cytochrome p450s?
Fe 2/3+
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coenzymes
carriers of reaction components
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which coenzyme carries electrons?
NAD(P)H + FAD(P)H2
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which coenzyme carry CO2 units
Biotin + thiamine pyrophosphate
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Niacin cannot be found in
FAD+
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niacin deficiency causes
pellagra
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what is not a presentation of pellagra?
dry mouth
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where is ethanol converted into acetaldehyde in the cell
cytosol
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where is acetaldehyde converted into acetate in the cell?
mitochondria
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what converts ethanol into acetaldehyde ?
alcohol dehydrogenase
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what converts acetaldehyde into acetate?
acetaldehyde dehydrogenase
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the conversion of ethanol into acetaldehyde and further into acetate succeeds in simultaneously converting
NAD+ into NADH
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alcohol inhibits...
conversion of tryptophan to niacin
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the oxidation of what by Glucose-6-phosphate dehydrogenase(G6PDH) generates NADPH
Glucose-6-phosphate
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the oxidation of G6P by G6PDH to produce NADPH is called the
pentose phosphate pathway
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when glucose 6 phosphate is oxidised by G6PDH what does it produce other than NADPH and H+ ?
6-phosphoglycono-δ-lactone
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genetically inherited G6PDH deficiency
X-linked recessive
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glutathione function
repairs oxidatively damaged cell membranes
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what is required to make glutathione?
NADPH
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RBCs are dependent on what to make NADPH?
G6PDH
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metabolism of 6 mercaptopurine by thiopurine methyl transferase creates what?
6-methyl mercaptopurine
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deficiency of thiopurine methyl transferase means that 6-mercaptopurine is converted into what?
6- thioguanine nucleotides
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what do 6-thiogunine nucleotides (TPMT deficiency) cause?
blockade of DNA synthesis and cell death
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what is not a level of enzyme control?
ionic modification
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what serpin (serine protease inhibitor) is this?
Prevents protease from attacking tissue
Prevents protease from attacking tissue
antitrypsin (a.k.a. anti-elastase)
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what serpin (serine protease inhibitor) is this?
controls activity of digestive enzyme
controls activity of digestive enzyme
pancreatic trypsin inhibitor
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what serpin (serine protease inhibitor) is this?
switches off blood clotting system
switches off blood clotting system
antithrombin III
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what part of ATP is transferred to amino acid residues for covalent modification/ phosphorylation
gamma-phsophate
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enzymes are phosphorylated by other enzymes called?
protein kinases
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phosphate groups are removed from enzymes by?
phosphatases
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for proteolytic activation, inactive zymogen/ pro-enzyme is activated by what?
proteolysis
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activation of zymogen/ pro-enzyme
done by removing part of the peptide chain, irreversible
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what is not an example of proteolytic activation?
lactic qcid
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proteolytic activation requires tight control by what?
natural inhibitors
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how do natural inhibitors affect proteolytic activation?
prevents enzymes becoming active in the wrong place and time
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what serine protease is this?
Digestive enzyme, molecular weight 25 kDa
Mature active protein has 3 polypeptide chains linked by disulfide bonds
Zymogen precursor is a single polypeptide
Active site contains catalytic triad of aspartate, histidine and
Digestive enzyme, molecular weight 25 kDa
Mature active protein has 3 polypeptide chains linked by disulfide bonds
Zymogen precursor is a single polypeptide
Active site contains catalytic triad of aspartate, histidine and
Chymotrypsin
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chymotrypsin's active site contains catalytic triad pf what?
aspartate histidine serine
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what is not a common feature of a serine protease?
protein kinase
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how is trypsinogen activated?
removal of amino acids 1-6
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trypsinogen is initially activated by?
enteropeptidase
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The blood clotting system requires the interaction of many _____to cause fibrin clot formation ?
serine proteases
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what is the difference between serum and plasma
serum is the fluid that remains after the blood has clotted. plasma is the fluid that remains when clotting is prevented
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which statement is incorrect about enzyme isoforms?
expressed from same gene
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Enzymes as diagnostic/prognostic markers
acute pancreatitis
acute pancreatitis
amylase and lipase
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Enzymes as diagnostic/prognostic markers
liver disease, osteoblastic bone disease (e.g. rickets)
liver disease, osteoblastic bone disease (e.g. rickets)
alkaline phosphatase
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Enzymes as diagnostic/prognostic markers
myocardial infarction, liver cell damage
myocardial infarction, liver cell damage
Glutamate-oxaloacetate transaminase (GOT)
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Enzymes as diagnostic/prognostic markers
liver cell damage
liver cell damage
Glutamate-pyruvate transaminase (GPT)
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Enzymes as diagnostic/prognostic markers
crush injuries
crush injuries
creatine kinase
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The standard measure of enzyme activity is The international unit. 1 IU is what?
the amount of activity that will convert 1 micromole (μmole,or 10-6 moles) of substrate per minute under standard defined conditions
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release of GPT and GOT in liver damage
both sharply increase then decrease
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GPT converts glutamate and pyruvate into
Alanine + a-ketoglutarate
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GOT converts Glutamate + Oxaloacetate into
Aspartate + a-ketoglutarate
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albumin liver function test typical value for healthy 30yr male
3.5-5.3 g/dL
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GOT (AST) liver function test typical value for healthy 30yr male
6-48 IU/L
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GPT (ALT) liver function test typical value for healthy 30yr male
7-55 IU/L
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Lower values indicate general loss of secretory function, but decrease could also be due to kidney disease
albumin
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total transaminase liver function test typical value for healthy 30yr male
13-103 IU/L
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Elevated in acute liver damage, but could originate from red blood cells or muscle, so not liver-specific
GOT (AST)
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A more specific indicator of liver damage than GOT, high activities tend to rule out muscle damage
GPT (ALT)
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GOT+GPT) – If both activities are high but with normal ALP = liver necrosis. Elevated levels could indicate alcohol toxicity, viral infection, cancer, others. Values >1000 IU/L could be paracetamol poisoning and/or severe/sudden liver failure. GOT/GPT rat
total transaminase
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Alkaline phosphatase (ALP) liver function test typical value for healthy 30yr male
45-120 IU/L
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Gamma glutaryl transpeptidase (GGT) liver function test typical value for healthy 30yr male
9-48 IU/L
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total bilirubin liver function test typical value for healthy 30yr male
>1.2 mg/dL
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direct bilirubin liver function test typical value for healthy 30yr male
>0.4 mg/dL
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If elevated, could indicate large bile duct obstruction. Caution: also high in Paget’s Disease of Bone, growing kids and 3rd trimester pregnancy
Alkaline phosphatase (ALP)
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slower clotting time indicates failure of the liver to synthesise and secrete blood clotting proteins such as prothrombin. Also used to monitor warfarin usage and Vitamin Ks tatus
Prothrombin time (INR)
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Sensitive to minor changes in liver functions, more ‘liver specific’ than transaminases. Raised by chronic alcohol/drug abuse.
Gamma glutaryl transpeptidase (GGT)
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is conjugated for excretion in the bile - if normal, jaundice results from problem upstream of the liver (some form of haemorrhage )
direct bilirubin
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Elevated indicates normal conjugation function in the liver, but failure toexcrete (bile duct obstruction)
total bilirubin
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what converts creatine and ATP into creatine-phosphate and ADP
creatine kinase
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creatine kinase is released upon
muscle damage
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what is used to treat paracetamol overdose?
N-acetylcysteine/methionine
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overdose of what drug's quinone derivative creates modified liver enzymes causing toxicity?
paracetamol
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resting blood glucose
0.72-0.99 mg/ml
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hypoglycaemia
<0.5 gm/ml
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hyperglycaemia
>1.8 mg/ml
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what is not an example of when enzymes can be used as therapeutic agents
As deoxidising agents - free radicals
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what enzyme is used In cancer therapy - Childhood Acute Lymphoblastic Leukaemia
asparaginase
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asparaginase facilitates the following equation:
asparagine + H2O -->aspartate + NH
how does this help with cancer therapy?
asparagine + H2O -->aspartate + NH
how does this help with cancer therapy?
plasma levels of asparagine are lower affecting tumour growth
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tissue-type plasminogen activator turns plasminogen into
plasmin
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plasmin turns fibrin clots int
peptides
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urease converts urea + H20 into
2NH3 +co2
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in kidney dialysis what happens to the NH3?
removed by carbon
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in kidney dialysis what happens to the CO2?
returned to blood and expired through lungs
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Other cards in this set
Card 2
Front
equilibrium
Back
forward and reverse reaction rates are equal
Card 3
Front
equilibrium constant K =
Back
Card 4
Front
which is not a way that enzymes decrease Ea
Back
Card 5
Front
active site bonds to substrates via
Back
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