Proteins and amino acids wace Flashcards
Describe amino acids-what are they?
What are they made up of
-monomers making up proteins
-at least 50 amino acids when chain can be classified as protein
-has amino (weakly basic) and carboxyl (weakly acidic) functional group
-hydrogen attached to central carbon
Describe proteins. What are they?
organic biopolymers containing amino acids joined by condensation to create polyamide
-polyamide chain folds into specific shapes to=protein w/many functions
What are the biological roles of proteins
Structural: main component of body tissue i.e. muscles, skin, ligaments, and hair
Catalytic: all enzymes=proteins, catalyse biochemical reactions
Immunological: antibodies
Signalling: hormones and receptors
What is the general formula for amino acids?
What are these amino acids called?
H2N-CH(R)-COOH
-α-amino acids or 2-amino acids
-have amino and carboxyl attached to same carbon (α-carbon)
What are the properties of amino acid side chains (r groups)
-can be polar or non-polar
-can include functional group behaving as proton donor (carboxyl)
-or proton acceptor (amino)
What is meant by essential amino acids
-body can synthesis 11/20 amino acids required to make protein=non-essential
-other 9 must be included in diet=essential amino acids
What is a zwitter ion
Provide an example diagram
-compound w/no overall electrical charge but which contains separate parts that are pos. and neg charged
-in aqueous solution their is an internal transfer of hydrogen group from COOH to NH2 to leave ion w/both negative and positive charge
Describe the acid-base properties of amino acids
-increase pH of solution by addition of OH ions=removal of H ion from NH3 group
-decrease pH by addition of H cause COO- part of zwitter ion to accept H+
Describe the solubility of amino acids
-generally soluble in water/insoluble in organic
-due to presence of zwitter ion, in water, ionic attractions between ions in solid a.acid are replaced by strong attractions bwn polar water molecules and zwitter ions
-extent of solubility depends on size and nature of R group
What occurs during a reaction between COOH and NH2
Provide and example diagram
-amide produced (CONH)
-molecule of water also produced
What occurs during condensation reaction between 2xamino acids
-peptide link formed(amide group linking functional groups)
-bond between carbon and nitrogen=peptide bond
-2-amino acids bonded together=dipeptide
-and small molecule of water
Difference between amide and peptide
amide: CNNCCNNCCNNC (alternate)
peptide: CNCNCNCNCNCN (don’t flip)
Define polypeptide
polymers formed by condensation polymerisation of amino acids
How to name polypeptides
-amino group on left N-terminal
-carboxyl group on right C-terminal
-3 letter short hand notation to list
-chain longer than 50=protein with more complex 3 dimensional structure
-with exception of C terminal, all end in yl
e.g. alanylglycylserine (Ala-aly-ser)
What is the primary structure of proteins
the number, type and sequence of amino acid units in a protein
What is a proteins secondary structure
secondary interactions w/other chains can cause twisting or folding
-alpha helix forms bwn amino acids that are 4 amino acids up a chain
-structure spiral shape
-if large r group=prevents helix forming
-beta pleated sheets forms when polypeptide chains lien up parallel to eachother
-H bonds then occur at regular intervals due to regular repeating(NCCNNCCN) backbone of protein chain
What is the protien data bank
-3D structural data of large biological molecules
-data obtained from xrays, etc
-structure then visualised
-data will include function location and interactions
-aids in understanding role of protein in human health and diseases
Define lock and key and induced fit
Provide example equation of enzyme-substrate reaction
-active sight is specific to the substrate, once attached, forms enzyme-substrate complex which allows bonds to be broken
-shape of active site can alter to accommodate substrate
How does pH effect enzyme function
-enzymes work best at optimum pH
-if pH is higher than optimum level, bonds bwn R groups can be disrupted
-pH effects functional groups-acidic COO- while NH+ basic
-ionic bonds broken
-structure not held in place, protein chain will unfold
-shape of the active site changes=denature
-no longer function
How does temperature effect enzyme function
low:
-low temp=low Ek of enzyme and substrates=less collision per unit time/less successful etc
-none/very few e-s complexes formed
-inactivated
high:
-higher Ek=break bonds of tertiary structure
-cause shape of enzyme to unfold=loss of active site=denatured
-w/out active site, e-s complex cannot form=cant catalyse reaction
Denaturation vs hydrolysis
-disruption of side chains of amino acid peptide bonds=changes tertiary structure of enzyme, no effect to primary
-hydrolysis breaks covalent peptide bonds=shorter peptide chains=effect to primary structure
What are the advantages and disadvantages of enzymes in industry
advantages
-effective at biological temps/pH levels=decrease cost and energy
-reusable and used for more time
-biodegradable=less pollution
disadvantages
-sensitive to pH/temp change
-costly to produce
-will only generally occur in aqueous
Describe the production of ethanol via hydrolysis of ethene
What are it’s requirements
-quicker process than fermentation
-moderate 300C,607Mpa catalyst (H3PO4)
-products fvrd at low temp (exothermic) moderate temp compromise rate and yield as high temp=higher reaction rate but lower yield
-high pressure fvrs both high yield and and fast rate. fwd favoured as 1 gaseous product and 2 reactants
disadvantage:
-ethanol produced this way increase CO2 in atmosphere when burnt
