Peptides and Peptide Bond

formed by the covalent interaction of two amino acids

A polypeptide

A molecule of water is eliminated for each peptide bond formed, what is the product called

dipeptide

what is the remaining portion of the AA in the peptide called

amino acid residue

What terminal ends are available for further reactions in peptide bonding

N-terminal and C-terminal

what catalyzes the condensation reaction of peptides

ribosomes

which type of molecules transport amino acids in to the ribosome

tRNA

Where are amino acids added successively of a growing peptide

the carboxyl terminal end

what is the primary structure of the protein

amino acid sequence

who analyzed the geometry and dimensions of peptide bonds in crystal structures of molecules containing one or a few peptide bonds

Linus Pauling and Robert Corey

C-N bond length is what percent shorter than found in usual amines

10%

in relevance to the planar structure of peptide bonds, why is the peptide bond short

because the C-N bond has some double bond character (40%) due to resonance with the C=O group

what are all peptide bonds approximately

coplanar

what reduces the degrees of freedom during folding in relation to the planar structure of peptide bonds

the rigidity of the peptide bond

what are the three main torsion angles of a polypeptide backbone

What degrees does the planarity of the peptide bond restrict w to in nearly all the main chain peptide bonds

180 (trans)

in rare cases, for a cis peptide bond which usually involves proline

w=0 degrees

in peptide bonds for the cis and trans configuration, what two bonds are nearly coplanar

C=O and N-H

what configuration is the peptide bond nearly always in because of it being favorable over cis

the peptide bond

what side are alpha C atoms on in C-N peptide bonds in the trans isomer

opposite sides

what side are alpha C atoms on in C-N peptide bonds in the cis isomer

same side

what is significant and found between functional groups attached to the alpha carbon in peptide bonds

steric hinderance is greater in the cis configuration

In relation to peptide bonds involving proline, what allows both the cis and trans configurations to have nearly equivalent energies , thus allowing proline to be found in the cis configuration

the cyclic nature

in relation to the formation and stability of peptide bonds- true or false formation of a peptide bond is not favored thermodynamically

true

in relation to the formation and stability of peptide bonds- formation of a peptide bond is not favored thermodynamically, what reaction is favored instead?

Hydrolysis of the peptide bond

what type of energy is used during translation

ATP

what are short peptides of a few residues called

oligopeptides

what are longer chain peptides of a few residues called

polypeptides

what are known as very long chains of polypeptides folded in to regular structure

proteins

what does the term polypeptide refer to

a chain of amino acids

what does the term protein refer to

the chain of amino acids after it folds properly and is (in some cases ) modified

true or false : proteins may consist of more than one polypeptide chain ( multimer)

true

what is the average molecular weight of an amino acid

138

when accounting for the abundance of AA’s in known proteins, the molecular weight of an average AA in a protein is about

128

why is the avg weight of an amino acid reside in a protein 110

because peptide bond formation removes a water molecule ( which has a molecular weight of 18)

how do you estimate the number of residues in a protein

by dividing the molecular weight by 110

true or false: the number of unique sequence possibilities is enormous in peptides

true

How many sequences do organisms typically rely on so necessary function will determine which sequences are constructed

30,000-35,000

True or False: Proteins ( polypeptides) contain an equal distribution ogf amino acids

False - they do not contain an equal distribution

Each of the amino acids, joined together by peptide bonds, in proteins (or polypeptides) have different properties determined by ____

R group side chains

what are the different properites that can make up R group side chains

acidic, basic, neutral, hydrophobic

What do amino acid side-chains direct

the folding of the nascent polypeptide into a functional protein and stabilize its final conformation

some proteins contain chemical groups other than amino acids, called conjugated proteins taht contain permenantly associated medical components… what is the non amino acid part called

prosthetic group

some proteins contain chemical groups other than amino acids, what id the prosthetic group for lipoproteins

lipids

some proteins contain chemical groups other than amino acids, what is the prosthetic group for glycoproteins

sugars

some proteins contain chemical groups other than amino acids, what is the prosthetic group for metalloproteins

specific metals