amino acids Flashcards
what are the 7 categories for the common amino acids
aliphalitic, hydroxylic, carboxylic, basic side chains, aromatic side chains, sulfur containing amino acids and imino
what are the 5 aliphatic amino acids
glycine, alanine, valine, leucine, isoleucine
what are the 3 hydroxyl amino acids
serine, threonine, tyrosine
what ability does the hydroxyl amino acid has
to form an ester linakge
what are the 2 carboxylic amino acids
aspartic acid and glutamic acid
complete this sentence
proteins that contain significant amounts of aspartic and glutamic acid tend to have… isolectric points
low
what are the 3 basic amino acids
lysine, histidine and aginine
lysine undergoes rapid reaction with reducing sugars which reduces what
the availability of this essential amino acids
arginine has a what group
guanidino
what is the R group for hstine
imidazole
what are the 3 aromatic amino acids
phenylalanine, tyrosine, tryptophan
what are the 3 amino acids of sulfur containing
cysteine, systine and methionine
what are the 2 types of imino acids
proline and hydroxyproline
proline and hydroxyproline are found where
collagen
free aminos acids and peptides gives flavor to foods what is the most common F.A.A
monosodium glutamate
what is used as flavorin agnets for meat or brothy flavour to soups
protein hydrolysate
the smell of a rotten eggs comes from what
hydrogen sulfide
what is putrefaction
a.a precursors of putrefactive odors and flavors in emat and fish
what happens to he free fatty acid to have bad odors and flavors
deamination or decarboxylation
what are the 2 amino acids that does not help to make helix formation?
proline and hydroxyproline
what are the 2 sub forms of beta sheet
parallel and antiparallel
suprahelix is found where
collagen
how do you form a suprahelix
3 supahelix
what is the classification of single proteins
albumins, globulins, glutelins, prolamines, scleroproteins, histones
what is albumins
protein that are soluble in neutral distilled water
what is globulins
protein that are soluble in neutral, dilute salt solutions, but not in distilled water
what is glutelins
are proteins that are solule in dilute acid or base, but not in neutral solution
what is prolamines
proteins that are soluble 50-90% ethanol and insoluble in water
what is scleroproteins
insoluble in water and neutral salts - resistant to enzymatic hydrolysis (generally structural proteins )
what is histones
basic proteins
what are the protein that food science has more interest
albumins and globulins
what is lipoproteins
proteins complexed with lipids (normally triglycerides). Abundant in nature and good emulsifiers
what is glycoproteins
proteins complexed with carbohydrate, which can range from simple sugars to heterosaccharide to polysaccharides. The carbohydrate is gnerally attached to the OH group of serine or theonine by an O-glycosidic bond. The carbohydrate is generally attached to the amide group of asparagine by an N-glycosidic linkage
what is metalloproteins
proteins complexed with a metal ion, which is generally loosely chelated
what is phophoproteins
proteins conjugate to ionarganic phosphates
this is the definition of what?
change in structure or conformation of a protein that does not involve breaking of peptide bonds
denaturation
continue the sentence
when the conformation of a protein is changed, many of its …. properties are also changed
physical
what are the common changes observed when denaturation takes place
- unfolding of the tertiary structure of the secondary structure makes the peptide bonds more accessible to proteolytic enzymes
- denaturation of protein generally results in a reduction in its solubility
- enzymatic activity may be decreased or lost
- viscosity generally increases, gelation may occur
- crystallization is no longer possible
what is the difference in agregation and gelation
agregation protein comes together; gelation fols to get a 3 dimension structures and water makes a creamy substance
factors contributing to denaturation
the most COMMON factor is HEAT.
others : ph, ionic strength, chemical agents, surface forces, combinations of the above
what the effect of pH can do
it affecs the overall charge of the molecule which affects the electrostatic bond contributions to the tertiary structure
what happens with hydrogens bond breakers and give an example
compounds that can effectively compete with the peptide linkage for H bonds can readil disrupt both tertiary and secondary structure. EX: urea
what can also disrupt H bonds
alcohols and acetone
how can detergents contribute to denaturation
theyr are able to bridge the hydrophobic and hydrophilic regions of the protein and result in the opening of the structure of the protein
how organic solvent denature proteins
they turn the env hydrophobic - can turn the protein macromolecule inside out
how surface forces denature proteins
thy reduce surface tension resulting in the formation of a foam .
Protein molecules actively rearrange themselves structurally to reduce their free energy with hydrophobic groups facing air and hydrophilic groups facing into the water - this arrangement can cause denaturation
what are some of the reactions that proteins do
- non enzymatic browning
- cross linking reactios
- formation of lysinoalanine
explain non enzymatic browning
foods that have a lot of proteins undergo browning when they are heated under low moisture conditions (MAILARD REACTION)
Maillard reaction involves what
an aldehyde group of a reducing sugar and a free amino group of an amino acid or the free amino group on a peptide or protein, such as lysine
explain cross linking reactions
reducing sugars are mainly absent, the crosslinking of proteins can occur at higher temepratires by the formations of amide bonds between COOH and NH2 groups on side chains of amino acid reidues
explain the formation of lysinoalanine
the preparation of protein concentrates and isolates often calls for the treatment of proteins with alkali in hte presence oh heat to modify the properties
what are the degrative reactions of proteins and explain
proteolysis - results in a reductuon in molecular weight and loss of functionality
putrefaction- associated with microbial spoilage. It involves degradation of free amino acids produced by proteolytic enzymes secreated by spoilage microorganisms
what are deaminases and decarboxylase and what they do
they are enzymes that remove amine groups and carboxyl groups
what amino acid makes fish smell bad
trimethylamine (TMA)
water binding in protein is associated with what
ionic species present (NH3 and COO) and hydrogen bonding sites (C=O, N-H)
what is moisture sorpton isotherm
3 levels water binding that can be associated with most proteins
continue the phrase
a protein’s ability to bind water is a function of its… compososition, overall structure and charge
amino acid
processing operations that involve removal of water can affect proteins what does it does?
freenzing and drying
what can freezing do to the proteins
changes in the structure. There is a loss of water binding capacity- loss of desirable texture
what does drying do to proteins
denaturing and or browning
what is drum drying
extensive denaturation and extensive browning if sugars are present
