Term
Enzymes
same enzyme types.. |
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Definition
Globular Protiens.
Usually catalyse forward and reverse reactions
have one or more active sites
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Term
| Induced fit model of Enzyme interaction with substrates1 |
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Definition
Each substrate has chemical groups on its surface area that are nearly complementary to chemical groups at anactive site. When a substrate settles into a site, the contact begins to strain some of the bonds. These bonds break and new bonds are formed.
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Term
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Definition
| The active site may also have interactions with charged or polar groups that can shift charges in the substrate. |
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Term
when the substrate fits into the active site it is activated, in a transitional state and can react.
what are the mechanisms used to bring about transitional states? |
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Definition
1 bringing substances together
2 positioning substrates
3 Acid/Base presence
4 Removal of water |
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Term
| Bringing substances together |
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Definition
| two substances that are in low concentration will not have opportunity for reaction. Enzymes can bring substances together and locally increase concentration - more chance for collision |
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Definition
| Enzymes position the substrate in space so there is more likelihood of an effective collision |
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Definition
The active site includes polar or charged amino acid groups that donate or remove hydrogen ions from the substrate
loss or addition of protons may cause bonds to form or break. |
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Definition
| Some enzymes bind substrates so that they are unable to react with water molecules. |
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Term
| Factors that Effect Enzyme activity |
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Definition
Temperature
PH
Salts
Substrate and Enzyme concentration /ratio
enzyme inhibitors |
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Term
| What determines enzyme shape? |
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Definition
| the shape of the molecule is determined by the hydrogen bonds that hold its' polypeptide arms in a particular shape and also by the tendancy of the noncharged nonpolar amino acids to avoid water. These bonds can be disrupted by slight changes in temperature |
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Term
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Definition
Suboptimal temperature
Below - Hydrogen bonding between polypeptide arms becomes inflexible and the induced shape change becomes difficult.
Above, Hydrogen bonding becomes too weak to hold the polypeptide arms in place. |
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Definition
PH 6-8 Is usually optimal.
above or below, enzyme structure and function are altered. The oppositely charged amino acids are sensitive to proton concentration |
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Term
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Definition
| disrupt the 3d shape of the enzyme due to extra ions |
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Term
| Substrate and enzyme concentration |
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Definition
| more equal ratios of substrate to enzyme lead to faster reaction rates . |
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Definition
A very similar molecule will compete with the substrate to fill the active sites of the enzyme to slow the reaction
competative inhibitors do not perminantly effect the enzyme. |
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Term
| Non compedative inhibition |
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Definition
A small molecule or Ion will bind or combine with the enzyme at a site other than the active site. The binding changes the shape of the active site so that the enzyme can no longer induce a fit.
e.g. Hg2+, Ag+, CN- |
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Term
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Definition
Enzymes can be inhibited or activated by the presence of a molecule at the allosteric site.
inhibitors prevent function
activators alter the active site so that substrate can successfully bind to it. |
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Definition
| The final product of a metabolic pathway can inhibit further production by acting as a non competative inhibitor for one of the enzymes at the very beginning of the pathway. |
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Term
| substrate control of enzyme activity |
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Definition
| increasing the concentration of the substrate can cause the enzyme to become active. |
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Definition
| stimulates a reaction pathway, the binding molecule bonds to the active site and activates the enzyme |
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Definition
Enzymes are assisted by cofactors that help catalyse reations or transfer electrons/atoms/functional groups from one substrate to another.
e.g. Fe2+ |
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Term
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Definition
cofactors that are complex biological molecules, e.g
FAD, NAD+, Both co-enzymes derived from vitamens |
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Term
EC1 oxidoreductase
EC2 Transferase
EC3 Hydrolases
EC4 Lyases
EC5 Isomerases
EC6 Ligases |
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Definition
catalyse oxidation reduction reactions
transfer functional groups
catalyse the hydrolysis of bonds
cleave various bonds by methos other than hydrolysis or oxidation
catalyse isomerisation within a single molecule
join to molecules with covalent bonds
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Term
EC 2.7 Phosphotransferases
kinase phosporylation |
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Definition
| enzyme that transfers phosphate groups from high energy donor molecules (atp) to specific substrates |
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Definition
| carry out phosphorolysis, the breaking of a bond with an inorganic phosphate group |
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Definition
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| How are allosterically regulated enzymes constructed |
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Definition
from one or more subunits. each subunit has its own active site, and the conplex oscillates between two shapes, one catalytically active and one inactive.
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