chem module 4

co-enzyme a contains what 7 things

thiol

amide

alcohol

diphosphate (phosoanhydride)

phosophate ester

carbohydrate

nucleobase

what does thiol (HS) do

building molecules

diphosphate + phosphate ester used for

solubility and binding

carbohydrate and nucleobase does what

molecular recognition for binding to enzyme active site

low molecular weight alcohols are

soluble in water due to hydrogen binding

oxidisation of alcohols

primary - aldehyde - carboxylic acid

secondary - ketone

tertiary - no oxidation

alcohol and carboxylic acids form

esters

NAD and NADH is used for

both are co enzymes

NAD - used for oxidising alcohol

NADH - used to achieve reverse reaction

amines are

basic and nucleophilic

amides are…. because

neutral and not very nucleophilic

the C double bond is polar and withdraws the N lone pair away from the nitrogen

amides can act as an…. and are

electrophile

and are quite resistant to hydrolysis

vancomycin

antibiotic isolated from soil organism

very effective against penicillin resistant bacteria

oxidation of the thiol leads to a

disulfide (s-s)

why are disulfides important

link peptide chains together forming a disulfide bridge which is important for protein/peptide shape

phosphorus containing functional groups

are strong acids and are generally ionised at physiological pH

phosphate groups can (2 features)

help solubilise compounds in water

are quite resistant to hydrolysis by water as the negative charge repels incoming nucleophiles

carbonyl

c double bonded to an o

aldehydes and ketones are examples of

carbonyl compounds

reactivity of aldehydes and ketones

undergo addition reactions

strong nu = attacks in the first step

weak = carbonyl reacts with and electrophile in the first step

addition reactions of aldehydes and ketones with an amine - strong nu (4 steps)

1. nucleophile attacks, and double bond breaks- RDS

2. deportation

3. O attacks the electrophile (H+

4. produces an unstable product

what happens after the addition of an amine to aldehyde

due to the unstable product, an imine is formed through the loss of water (c double bonded to N + CH3)

this is reversible

chemistry of vision - at the start

reversible imine formation is a ket part of vision

retinol is oxidised to retinal

the aldehyde of the retinal reacts an amine of the protein (the opsim)

chemistry of vision - what happens once the retinal forms an imine with opsim?

formation of trans alkene shape of bound retinal, which changes the shape of the protein which sends signals from the eye to the brain

11-trans retinal is isomerized by enzymes and recycles back into the 11 cis isomer

addition reactions of aldehydes/ketones with alcohol (weak nu) (3 steps)

nu is too weak to effectively attack a c double bond o in the first step

1) the double bond reacts with an electrophile (H+/acid catalysed)

2) nu attacks (RDS)

3) deprotination

aldehyde/ketone + alcohol form

hemiacteal

hemiacteal + alcohol forms

acteal + water

aldehydes compared to ketones

• can both undergo addition reactions with strong and weak nu

• aldehydes are more reactive than ketones

glyceraldehyde

• smallest sugar unit (c3,o3,h6)

• has a chiral carbon

following rules only apply to glyceraldehyde

• R = D

• S = L

fisher projections

aldehyde goes at the top (CHO)

bonds up and down - project into the page

what does the squiggly line in the cyclic molecule mean

two possible isomers at this point and at that position

matarotation

equlibrirm of the interconversion of cyclic hemiacteal disteroisimers

has to be in solution for equilibrium to be established

acyclic

open change form, same molecule drawn in different orientation

6 membered ring is called

pryanose

5 membered ring is called

furanose

reducing sugars

contain functional group that can eaisly act as a reducing agent and therefore can be oxidised

hemiacetals included mean reducing sugar