Lecture 2- Stereochemistry

In molecules with n uniquely different chiral carbons, the total number of possible configuration is ____.

2^n

A linear aldose begins with an aldehyde group. It ends with -CH2OH group, and has HCOH carbons in between. The chiral carbons include the _____.

HCOH carbons

cis

#NAME?

trans

#NAME?

R

clockwise

S

counterclockwise

When citric acid is bound to the enzyme aconitase, the two -CH2COOH groups attached to the central carbon atom have ____ _probabilities of interacting with groups on the enzyme.

different

The term configuration applies to

R vs. S & cis vs trans
Note, on forms can be converts into the other by breaking covalent bonds & swapping positions of atoms

The naming system which is based on a comparison to the standard, glyceraldehyde, is the ______ system.

D vs L
- All AA are L except for glycine

Glycerol and glyceraldehyde each have

3 Cs

Ibuprofen has one chiral carbon. The most inexpensive way to synthesize it is as a racemic mixture of R and S forms. The % of ibuprofen molecules in the pill you buy which are physiological active is _____.

50%
- only one enantiomer is active

Levo is the root word for ____--

left

Linear aldose sugars have their aldose group C-1. The D carbon is always

the highest numbered chiral carbon

All sugars have the same high-numbered end as D-glyceraldehyde, namely chiral HCOH followed by symmetric CH2OH

...

In chiral AA, the L carbon is in the _____

backbone (HN-C-carbonyl)

Except for glycine, the AA prodcuts produced by passing a spark thru a mixture of NH3, CH4, H2O, and H2 are _____.

50/50 D/L
- catalysts exert no chiral forces on the reactants, so both products are equally likely

A chiral carbon is viewed with its lowest priority group (4) at the rear. When the other groups in front are considered in order 1->2->3 and they are arranged clockwise, the configuration is

R

The designations which are based on the rotation of plane-polarized light of a particular wavelength are

d and l
- whole molecule rotates to the right (d=dextro) or to the left (l=levo)

The stereospecificity of biological reactions can be demonstrated by considering a model requiring attachment of a substrate to an enzyme at a minimum of _____ pt.s

3

If a D AA is incorporated into the normal R-handed alpha helix of a protein, there will be steric conflicts between the _____.

side chain R group and a backbone carbonyl O atoms