Biochemistry 2280A Lecture Notes - Lecture 3: Lysine, N-Terminus, Alanine

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14 Jan 2016

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Not all proteins share 3d folding; some exist as natively unstructured proteins (random, unfolded conformations) The function of a protein depends on its structure which depends on the amino acid sequence. Are linear polymers of 50- 30,000 amino acids. The peptide bond is formed by the carboxyl group from one amino acid and the amino group (nh3+) of another. The reaction is a condensation reaction. There are polarities on the two opposite ends. Amino (n- ) terminal is positive; carboxyl (c- ) terminal is negative. Polypeptides are elongated through the c- terminal. The general pattern is n- c- c- n- c- c( aka the backbone) The peptide bond shares double bond characteristics through resonance between the c- o and c- n bonds. Bonds are all covalent. There is no rotation around the peptide bond; this constrains its flexibility and prevents certain folding patterns. Proteins structures have increasing complexity from primary secondary tertiary quaternary.

Related Questions

For each of the following sentences, fill in the blanks with the best word or phrase selected from the list below. Not all words or phrases will be used; each word or phrase should be used only once. Proteins are ______________ built from amino acids, which each have an amino group and a _____________ group attached to the central _______________. There are twenty possible _______________ that differ in structure and are generally referred to as âR.â In solutions of neutral pH, amino acids are _______________, carrying both a positive and negative charge. When a protein is made, amino acids are linked together through _______________, which are formed by condensation reactions between the carboxyl end of the last amino acid and the ___________________ end of the next amino acid to be added to the growing chain.

a: amino	b: ionized	c: polypeptides
d: alpha-carbon	e: length	f: protein
g: carbon	h: noncovalent	i: R group
j: carboxyl	k: peptide bonds	l: side chains

m: hydroxide

indigofrog836

1. A sequence of amino acids in a certain protein is found to be â Ser â Gly â Pro â Gly â

The sequence is most probably part of a(n):

a. beta turn

b. antiparallel beta sheet

c. alpha-helix

d. parallel beta-sheet

e. alapha-sheet

2. Which statement about peptides bonds is NOT TRUE?

There is perfectly free rotation about the peptide bond.

The peptide bond has partial double-bond character.

The peptide bond is shorter than a normal carbon-nitrogen single bond.

The peptide bond usually has a trans configuration with respect to the alpha-carbons of the two amino acids involved in the peptide bond.

Peptide bonds are made via condensation of an amine and a carboxylic acid with loss of water.

3. Which of the following statements about proteins is FALSE?

	Active proteins are generally very loosely structured.
	In water-soluble proteins, hydrophobic amino acid residues are generally buried and not exposed to water.
	Primary structure determines tertiary structure.
	Secondary structure is regular, recurring arrangements in space of nearby amino acid residues in a polypeptide.
	Quaternary structure involves the interaction of subunits in a protein with more than one polypeptide chain.

maroonwallaby335

thank you

Biochemistry 2280A Lecture Notes - Lecture 3: Lysine, N-Terminus, Alanine

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