Exam 4 Old Flashcards
Which of these situations would result in a decrease of enzymes reaction rate?
Enzyme provides more efficient path toward product
Enzyme decreases entropy of substrate in activate site
Enzyme destabilizes transition state
Enzyme increases entropy of surroundings
Enzyme mutation causes increase in kcat
Enzyme destabilizes transition state
Which of these statements regarding critical aspects of enzyme structure and function is incorrect?
Enzymes typically bind to substrates with low specificity
Enzymes typically bind to substrates with high affinity
Enzymes undergo conformational change upon substrate binding
Enzyme function is highly regulated
Each of these statements is correct
Enzymes typically bind to substrates with low specificity
Which of the following statements is false for the reaction s->p
Enzymes increase the rate constant for the reverse reaction
Enzymes decrease the activation energy of reaction
Enzymes decrease the standard free energy change for a reaction
Enzymes do not alter equilibrium constant
Enzymes increase the rate constant for the forward reaction
Enzymes decrease the activation energy of reaction
Vitamin B1 is required for the function of the transketoloase enzyme. It is considered a
Coenzyme and the enzyme without B1 bound is called an Apo enzyme
During the chymotrypsin mechanism, ___ acts as a general acid and base while ___ acts as a nucleophile
Histidine; serine
Think of energy coordinate diagrams and the chymotrypsin mechanism. given that the tetrahedral intermediate in the chymotrypsin mechanism is equivalent to the transition state for this enzyme, which of the following statements would be false?
The tetrahedra intermediate is less stable, energetically than the substrate
The tetrahedral intermediate has lower energy than the substrate
The tetrahedral intermediate is attached to chymotrypsin with a covalent bond
Chymotrypsin has more intermolecular forces with tetrahedral intermediate then it does with the substrate
Chymotrypsin binds the tetrahedral intermediate with greater affinity than it does the substrate
The tetrahedral intermediate has lower energy than the substrate
This image shows the proposed mechanism for Covid like protease. This enzyme carries out which type of reaction
Both acid base and covalent catalysis
Let’s take a closer look at covid Papin like protease mechanism. When the substrate docks to this protease, Asp pushed closer to His, allowing His to convert Ser into a strong ___.
Nucleophile
An inhibitor that binds to both the free enzyme and the enzyme substrate complex, but with unequal affinity is known as
Mixed non competitive
A study is carried out in the absence and presence of a pure non competitive inhibitor. If the inhibitor is increase significantly during the experiment, the Vmax would ___ and the Km would ___
Decrease; no change
Given the Lineweaver-Burk equation provided below, representing an enzyme in the absence and presence of an inhibitor, we can see that this is a ___ inhibitor
Control: y= 1.37x +42
With 15 nm inhibitor: y= 1.37x + 65
Uncompetitive
If an allosteric enzyme is treated with a positive allosteric modulator, the K 1/2 will ___ and the initial velocity vs substrate concentration will shift ____
Decrease; left
Elastin is a serine protease that is first translated as a larger protein. Once cleaved, it is fully activated. Based on the information provided, this protein is
A zymogen/ proemzyme
Each of the following is a feature of signal transduction except
Altered rates of gene expression
Protein conformational changes
Covalent protein modification
Signal amplification
All of these are features
All of these are features
The hormone alpha-MSH helps to decrease appetite. This hormone is produced by th e POMC neurons in the anterior pituitary and when released form these cells, alpha-MSH binds to anotexigenic neurons also located in the anterior pituitary. In this situation alpha-MSH is acting as a ____ hormone
Paracrine
