Stereochemistry and Drug Action

Question 1

chiral

Answer 1

any object that cannot be superimposed with its mirror image
1 carbon atom, 4 different substrates

Question 2

stereoisomer

Answer 2

compounds that have the same molecular formula and differ only in the stereo chemical arrangement of functional groups about 1/more atoms

must break bonds to convert

Question 3

enantiomers

Answer 3

non-superimposable mirror images of one another
all properties are identical except the way they rotate in plane polarized light

Question 4

Will two enantiomers be able to bind to the same object?

Answer 4

no

Question 5

+/- designations

Answer 5

direction of rotation caused by the enantiomer
provide no information about chiral center
+ is right
- is left

Question 6

d/l designations

Answer 6

refer to direction of rotation caused by the enantiomer
d is right
l is left

Question 7

D/L designations

Answer 7

refer to the configuration/steric arrangement about a chiral center

Question 8

R/S designations

Answer 8

designates configuration about a chiral carbon atom
R- clockwise
S- counterclockwise

Question 9

Stereospecific

Answer 9

only one stereoisomer can bind to a receptor, the other is inactive at the receptor

Question 10

Stereoselective

Answer 10

one enantiomer is preferred over the other

Question 11

Diastereomers

Answer 11

have at least 2 chiral centers
neither superimposable/ mirror images

Question 12

Geometric isomers

Answer 12

result from restricted rotation about a carbon-carbon bond
can occur due to the presence of either a double bond or an alicyclic ring

have different physical and chemical properties, one isomer may have better receptor fit

Question 13

z isomer

Answer 13

strongest substituents are on the same side

Question 14

e isomer

Answer 14

strongest substituents are on opposing sides

Question 15

Conformational isomers

Answer 15

nonsuperimposable orientations resulting from free rotation of a single bond

Question 16

Preferred conformation relies on

Answer 16

repulsive and attractive forces

Question 17

Which are energetically favored: trans, gauche, or eclipsed ?

Answer 17

trans and gauche

Question 18

How does a drug molecule obtain the energy required to convert its preferred conformation to its active conformation?

Answer 18

energy is released when a drug binds/interacts with the receptor

Question 19

If energy required to form the active conformation is greater than energy released the drug is?

Answer 19

inactive

Question 20

Benefits of conformational restriction

Answer 20

specific agonist/ antagonist
eliminate toxic/undesirable effects
increase the duration of action

Question 21

A conformationally rigid analog with all the necessary groups in the proper orientation would decrease and increase what?

Answer 21

decrease the energy requirements but increase the affinity and activity of the receptor

Question 22

A flexible drug that binds to a single receptor requires what to assume a favorable conformation?

Answer 22

energy