Structural Features of Beta-Strands in Proteins

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The F1 component of the ATP synthase enzyme has 3 β subunits with each adopting a different ______ at a given time (loose, open, and tight conformations).

conformation

The hydrophobic effect stabilizes ______ structure.

protein

Aromatic R Groups can contribute to the ______ effect.

hydrophobic

Cys can form ______ bonds.

disulfide Signup and view all the answers

Cys has a positive hydropathy index, classified as polar due to its SH group's ability to act as a weak acid and be involved in weak ______ bonds.

hydrogen Signup and view all the answers

Amphitropic Proteins have a reversible lipid attachment process, where the lipid attachment is __________

covalently Signup and view all the answers

B-strands never occur singly, but always as part of a ________

sheet Signup and view all the answers

In a b-strand, each residue extends ________ Å

3.5 Signup and view all the answers

β-barrel proteins have no unpaired hydrogen bonding main chain groups, making them suitable as __________ proteins

membrane Signup and view all the answers

All b-barrel membrane proteins have an even number of b-strands, reflecting the requirement that they be inserted ________

pairwise Signup and view all the answers

Since side chains in a beta strand project alternately on either side, all hydrophobic residues fall on one side and the hydrophilic residues fall on the other side of the ________ strand

beta Signup and view all the answers

The hydrophobic side faces the __________ and the hydrophilic side faces the interior of the barrel.

exterior Signup and view all the answers

Even number of strands in OMP structures results in strands that do not ______ each other.

cross Signup and view all the answers

Periplasmic loops in OMP structures are often very ______, sometimes forming β-turns.

short Signup and view all the answers

Barrels with 8-10 strands in OMP structures have a solid core filled with ______ residues.

hydrophilic Signup and view all the answers

Intermediate-sized b-barrels with 16-18 strands in OMP structures have aqueous pores generally with inserted ______.

loops Signup and view all the answers

Large barrels with 22–26 b-strands in OMP structures generally have a plug domain that ______ into and closes most of the channel.

inserts Signup and view all the answers

Match the OMP structure characteristics with their corresponding descriptions:

Even number of strands = Results in strands that do not cross each other Antiparallel β sheet = All b-strands in OMP structures are arranged in this manner Extracellular loops are often long = Characteristic feature of OMP structures with 16-18 strands Periplasmic loops are very short = Common in OMP structures such as OmpX with 8 strands Signup and view all the answers

Match the OMP examples with their respective number of beta strands:

OmpX = 8 strands OmpF = 18 strands FepA = 22 strands VDAC = Odd number of beta strands Signup and view all the answers

Match the OMP structure sizes with their corresponding features:

Barrels with 8-10 strands = Have a solid core filled with hydrophilic residues Intermediate sized b-barrels with 16-18 strands = Have aqueous pores generally with inserted loops Large barrels with 22–26 b-strands = Generally have a plug domain that inserts into and closes most of the channel VDAC - voltage-dependent anion channel = Made up of an odd number of beta strands Signup and view all the answers

Match the location descriptions to the corresponding termini in OMP structures:

N and C-termini always periplasmic and next to each other = Characteristic positioning in OMP structures Helix at N-terminus inserts into pore = Specific feature observed in certain OMP structures Most abundant OM protein in eukaryotic mitochondria = VDAC - voltage-dependent anion channel Acts as an ion channel; also plays a role in apoptosis = VDAC - voltage-dependent anion channel Signup and view all the answers

Match the residue types to their location in the beta-barrel structure:

Hydrophobic residues = Found on the side facing the exterior of the barrel Hydrophilic residues = Found on the side facing the interior of the barrel Interior residues = Residues within the beta-barrel structure Bilayer facing residues = Residues facing the lipid bilayer Signup and view all the answers

Match the amino acid property with its corresponding description:

Negatively Charged R Groups = Can form ionic bonds Aromatic R Groups = Can contribute to the hydrophobic effect Polar, Uncharged R Groups = R groups can form hydrogen bonds Nonpolar, aliphatic R groups = Contribute to hydrophobic effect Signup and view all the answers

Match the protein symmetry with its example:

Quasi-symmetry = F1 component of the ATP synthase enzyme Anti-parallel symmetry = VDAC protein Signup and view all the answers

Match the number of beta strands with the corresponding OMP structure size:

8-10 strands = Small barrels with a solid core filled with hydrophobic residues 22–26 strands = Large barrels generally with a plug domain that closes most of the channel Signup and view all the answers

Match the location in a beta strand with its characteristic feature:

Hydrophobic side = Faces the lipid bilayer Hydrophilic side = Faces the interior of the barrel Signup and view all the answers

Match the residue type with its specific location in a beta-barrel structure:

Cys = Located in positions where disulfide bonds can form Aromatic R Groups = Located to contribute to the hydrophobic effect Signup and view all the answers

Match the effect with its role in stabilizing protein structure:

The hydrophobic effect = Stabilizes protein structure Signup and view all the answers

Match the amino acid classification with its rationale:

Cys classified as polar = Due to its SH group's involvement in weak hydrogen bonds Signup and view all the answers

Match the termini description with its corresponding location in OMP structures:

Periplasmic loops = Often forming beta-turns Signup and view all the answers

Match the number of subunits with their conformations in a protein complex:

3 beta subunits = Adopting different conformations (loose, open, tight) at a given time Signup and view all the answers

Match the lipid attachment process with its characteristic for Amphitropic Proteins:

Reversible lipid attachment process = Where lipid attachment can occur Signup and view all the answers

Match the following terms related to protein structure with their corresponding descriptions:

Anti-parallel beta strands = Side chains project alternately on either side Hydrophobic effect = Stabilizes protein structure Polar, Uncharged R Groups = Can form hydrogen bonds Cys = Can form disulfide bonds Signup and view all the answers

Match the following characteristics of VDAC (Voltage-Dependent Anion Channel) with their functions:

Solid core filled with hydrophobic residues = Forms the interior of the barrel Aqueous pores in OMP structures = Generally have inserted proteins Plug domain in large barrels = Inserts into and closes most of the channel Reversible lipid attachment process = Characteristic of Amphitropic Proteins Signup and view all the answers

Match the residue types with their specific locations in beta-barrel structures:

Aromatic R Groups = Contribute to the hydrophobic effect Negatively Charged R Groups = Located on the hydrophilic side Positively Charged R Groups = Located on the hydrophilic side Cys = Classified as polar due to its weak acid ability Signup and view all the answers

Match the following amino acid properties with their corresponding descriptions:

Hydropathy index of Cys = Positive due to SH group's weak acid ability 20 naturally occurring amino acids = Include nonpolar, aliphatic R groups Quasi-symmetry proteins = Have multiple copies with different conformations F1 component of ATP synthase enzyme = Has 3 β subunits with different conformations Signup and view all the answers