Enzyme pt. 2 (Quiz 1)

Question 1

Enzymes are classified according to the ___?

Answer 1

type of reaction they catalyze

Question 2

Classification of Enzymes

• EC First Integer: ____ of enzyme catalyzed reactions
• 2nd integer: a ___
• 3rd number: ___ depending on 1st and 2nd integer
• 4th number: ____

Answer 2

Classification of Enzymes
* six major classes
* a subclass
* subclassification
* serial number

Question 3

_______

rate of a reaction between ____ molecules is ____ if they are abstracted from ____ and held in ____ proximity to each other (in the enzyme’s active site)

Answer 3

Facilitation of Proximity
* two
* enhanced
* dilute solution
* close

Question 4

to increase the effective concentration of the reactants

Answer 4

Propinquity effect

Question 5

In Covalent catalysis – amino acid side chains :

Answer 5

nucleophilic groups

Question 6

This mechanism involves the transient covalent binding of the substrate to an amino acid residue in the active site. Generally, this is to the hydroxyl group of a serine, although the side chains of threonine, cysteine, histidine, arginine and lysine can also be involved.

Answer 6

covalent catalysis

Question 7

Modes of Enhancement of Rates of Bond Cleavage / Catalytic Mechanisms (6)

Answer 7

• Facilitation of Proximity
• Covalent Catalysis
• General Acid-Base Catalysis
• Binding Energy Catalysis
• Metal-ion Catalysis
• Molecular Distortion and Shape Change

Question 8

this would determine the ionization state of an amino acid side chain

Answer 8

pH of the active site

Question 9

For acid-base catalysis, _____ is the most versatile amino acid due to its pk, which means that in most physiological situations it can act as either a proton donor or proton acceptor.

Answer 9

histidine

Question 10

refers to weak acids

Answer 10

proton donors

Question 11

refers to weak bases

Answer 11

proton acceptors

Question 12

______

• The preceding ____ groups can potentially serve as either proton donors or proton acceptors.
• This is ____ on many factors including the ____ nature of the substrate, any ____ involved, and the ___ of the active site
• Generally,these ____ will interact together with the ____, or in conjunction with water or other weak, organic acids and bases found in cells.

Answer 12

• acid-base catalysis
• functional
• dependent, molecular, co-factors, pH
• amino acids, substrate

Question 13

_____

• is involved in a majority of ____ reactions . it needs to be distinguished from ____ acid-base catalysis.
• the _____ aids in stabilizing the transition state via ____ of a proton.
• Therefore, the rate of the _____ is dependent on the _____ as well as the appropriate ____ state.

Answer 13

General Acid-Base Catalysis
* enzymatic
* specific
* buffer
* donation or removal
* reaction
* buffer concentration
* protonation

Question 14

catalytic factors in the binding of a substrate and enzyme:

1) transient____ of substrate and enzyme ____ by reducing the ______ of the two molecules,
2) solvation ____ of the _____ thermodynamically favorable, and
3) substrate and enzyme _____ changes.

Answer 14

• limiting
• movement
• relative motion (or entropy)
• distruption
• water shell
• conformational

Question 15

accounts for the overall lowering of activation energy for a reaction, and it can also be considered as a catalytic mechanism for a reaction.

Answer 15

binding energy

Question 16

_______

• Various metals, all ____ charged and including zinc, iron, magnesium, manganese and copper, are known to form ____ with different enzymes or substrates.
• This ____ complex can aid in the _____ of the substrate in the ______, and
• metals are known to mediate _____ reactions by ____ changes in their ____ states (like Fe³+ to Fe2+).

Answer 16

Metal lon Catalysis

• positively
• complexes
• metal-substrate-enzyme
• orientation
• active site
• oxidation-reduction
• reversible
• oxidation

Question 17

Clinical Use of an Enzyme pt.2

• Enzyme activity can be ____ genetically
• A _____ in an enzyme can alter its ____ affinity, co-factor ____ stability etc. which can be used as a _____ in comparison with ____ enzyme
• Loss of _____ presence due to genetic mutation as detected by ____ enzyme substrate and/or lack of ____ leading to a _____
• NOTE: _____ that identify specific messenger RNA or DNA sequences are replacing many ____ enzymatic based markers of genetic disease

Answer 17

• altered genetically
• mutation
• substrate
• binding
• diagnostic
• normal
• enzyme
• increased
• product
• dysfunction
• PCR techniques
• traditional

Question 18

Clinical Use of Enzyme pt. 1

• Enzyme Activity in Body Fluids Reflects ____ Status
• Enzyme Activity Reflects the Presence of ____ or _____
• Activity of serum enzymes _____ in presence of an _____
  (ex. some insecticides inhibit serum cholinesterases)
• Determine co-factor ____(like an essential vitamin) by ____
  (ex. add back vitamin to assay, if activity increases, suggests deficiency in that vitamin)

Answer 18

• Organ
• Inhibitors or Activators
• decreases
• inhibitor
• deficiencies
• enzyme activity

Question 19

An ____ is a blood test or urine test that measures levels of certain enzymes to assess how well the body’s systems are functioning and whether there has been any tissue damage.

Answer 19

enzyme test

Question 20

Common Enzymes used for clinical diagnosis

Answer 20

• alanine aminotransferase (ALT, also called glutamate pyruvate transaminase, GPT)
• alkaline phosphatase
• amylase
• aspartate aminotransferase
• creatine kinase
• lactate dehydrogenase

Question 21

– evaluate liver function and diagnose liver diseases such as hepatitis and cirrhosis.

Answer 21

alanine aminotransferase

Question 22

assess liver and bone disorders. when levels are elevated it can indicate cholestasis (bile flow obstruction), liver disease, or bone diseases such as Paget’s disease

Answer 22

alkaline phosphatase

Question 23

diagnose acute pancreatitis, and other conditions like salivary gland infections or intestinal obstruction

Answer 23

amylase

Question 24

assess liver function. Elevated levels can indicate liver damage but can also be associated with heart or muscle injury

Answer 24

aspartate aminotransferase

Question 25

diagnose **muscle damage**, including conditions like **myocardial infarction** (heart attack) and **rhabdomyolysis**

Answer 25

creatine kinase

Question 26

diagnosis of various conditions, including ***hemolysis*, liver disease, and certain cancers** (tissue damage)

Answer 26

lactate dehydrogenase

Question 27

Chemical reaction need an initial input of energy

Answer 27

THE ACTIVATION ENERGY

Question 28

During this part (activation energy) the reaction of the molecules are said to be in a ?

Answer 28

Transition state

Question 29

**Enzyme makes the reactions go faster by...** * Increasing the ____ make **molecules move faster** * _____ systems are **very sensitive** to _____ changes. * Enzymes can increase the _____ of reaction without increasing/requiring an increase in the ______ * They do this by **lowering** the _ energy. * They **create a new reaction pathway** "a ____"

Answer 29

* temperature * Biological, temperature * rate of reactions, temperature. * activation energy. * "a short cut"

Question 30

**Enzyme Specificity** * Enzymes have varying degrees of ____for substrates * Enzymes may recognize and catalyze: o a ___ substrate o a ___ substrate o a **particular type** of bond

Answer 30

* specificity o **single** o **group of similar**

Question 31

**Lock-and-Key Model** In the lock-and-key model of enzyme action: * The **active site** has a ___ shape. * Only substrates with the ____ shape can fit. * The ____ is a key that fits the lock of the ___ .

Answer 31

* **rigid** shape. * **matching** shape * substrate, * active site

Question 32

**The Lock and Key Hypothesis** * **Temporary** structure called the _____ complex **formed** * **Products** have a different ____ from the substrate * **Once formed,** they are ____ from the ____ * **Leaving** it ___ to become **attached** to another ____ * This *explains enzyme specificity* * This *explains the loss of activity* when enzymes denature

Answer 32

* enzyme-substrate * shape * released, active site * free, substrate

Question 33

**Enzyme changes shape with substrate** people-pleaser na enzyme

Answer 33

Induced Fit Theory

Question 34

The **induced-fit model** of enzyme action: * The **active site is ____, not rigid**. * The **shapes** of the enzyme, active site, and substrate ____ the fit, which improves _____. * There is a ___ range of ____ specificity..

Answer 34

* flexible, * adjust to maximum, * catalysis. * **greater** range, * **substrate** specificity

Question 35

**The Induced Fit Hypothesis** * Some proteins can ___ their shape (______) * When a **substrate combines** with an ____, it **induces a change** in the **enzyme's** ____ * The **active site** is then ____ into a ____ conformation making the __ **environment suitable** for the reaction * The ____ of the substrate are ___ to make the reaction ___ (lowers activation energy)

Answer 35

* change, (conformation) * enzyme, * conformation * moulded, precise, chemical * bonds, stretched, easier

Question 36

Enzyme Catalyzed Reactions * When a **substrate (S) fits properly in an active site**, an ____ complex is formed: **E + S ⇌ ES** * **Within the active site** of the ES complex, the reaction. occurs to ___ **substrate** **to product (P):** **ES → E + P** * The **products are then ___ **, **allowing another** **substrate molecule** to **___** the enzyme o this cycle *can be repeated millions* (or even more) times per minute * The **overall reaction** for the conversion of substrate to product can be written as follows: **E + S ⇌ ES → E + P**

Answer 36

* enzyme-substrate (ES) * convert: * released * bind

Question 37

**Enzymatic reaction steps**

Answer 37

1) Substrate approaches active site 2) Enzyme-substrate complex forms 3) Substrate transformed into products 4) Products released 5) Enzyme recycled

Question 38

**Enzyme Kinetics** ***Enzyme activity*** can ***be assayed*** in many ways

Answer 38

o disappearance of substrate o appearance of product o continuous assay o end point assay

Question 39

The ___ of an enzyme-catalyzed reaction is dependent upon the ____

Answer 39

velocity (V), substrate concentration [S]

Question 40

at _, . A significant amount of **substrate has not yet been converted to product.**

Answer 40

initial velocity of a reaction

Question 41

at this point, **addition of more substrate will not increase the rate of the reaction**

Answer 41

maximal velocity of a reaction

Question 42

The ___ **describes the kinetic behavior** of many enzymes

Answer 42

Michaelis-Menten equation

Question 43

Michaelis-Menten equation o **maximum rate** that can be observed in the reaction o **substrate is present in excess** o **enzyme can be saturated** (zero order reaction)

Answer 43

at Vmax

Question 44

o a **constant that is related to the affinity of the enzyme** for the substrate o units are in terms of concentration

Answer 44

michaelis constant, Km

Question 45

Enzymes are never expressed in terms of their ____ (as mg or µg etc.) but are expressed only as ____.

Answer 45

concentration, activities.

Question 46

* ____ **moles of substrate converted to product per unit time**. o The **rate** of appearance of ___ or the rate of disappearance of ____ o **Test the absorbance**: __

Answer 46

* Enzyme activity o product, substrate o **spectrophotometer**

Question 47

Factors affecting enzyme activity

Answer 47

* Concentration of substrate * Concentration of enzyme * Temperature * PH * Activators * Inhibitors

Question 48

the **increased in velocity is proportional to the substrate concentration**

Answer 48

Substrate concentration: **non-enzymatic reaction**

Question 49

, a **faster reaction occurs but it reaches a saturation point** when all the enzyme **molecules are occupied**.

Answer 49

substrate concentration: **enzymatic reactions**

Question 50

Elevated alkaline phosphatase levels can indicate **____** (**bile flow obstruction**), *liver disease*, or *bone diseases* such as **_____ disease**

Answer 50

* **cholestasis** * **Paget's disease**