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mcb124
na
106
Science
Undergraduate 1
02/02/2013

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Term
minor grove
Definition
contains the uracil O2 and guanine N2 atoms, narrow in A  tracts
Term
node
Definition
where DNA duplexes cross in a loop or supercoil
Term
beta strand
Definition
contains almost 2 residues/turn and extends 3.2-3.4Amstrong/residue
Term
fold
Definition
classification ofhe 3d path of polypeptide or nucleic acid
Term
A-form
Definition
most common geometry of RNA helix
Term
secondary structure
Definition
regular structures characterized by repeating backbone torsion angles and maximal backbone H-bonds.
Term
rotamer
Definition
side-chain conformation classification based on frequent occurrence
Term
major groove
Definition
provides the widest access to the basepairs in B-DNA helices
Term
multimers
Definition
a protein complex, contains more than one subunit
Term
orthologs
Definition
proteins from a different organisms with a similar functions
Term
stacking interactions
Definition
result of London dispersion forces between planar bases
Term
helical repeat
Definition
a protein sequence pattern that places residues on one side of an α-helix
Term
tertiary interactions
Definition
3-D contacts between residues that are far apart in sequence
Term
loop
Definition
polypeptide segment of a folded protein which does not adopt compact “regular” secondary structure
Term
quadraplex DNA
Definition
4 polynucleotide strands joined by Hoogstien-paired guanine bases
Term
base step
Definition
two consecutive base pairs
Term
p
Definition
disrupts backbone hydrogen bonding when in helices and sheets
Term
w
Definition
a fluorophore that absorbs light maximallly at 280 nm
Term
g
Definition
often found in turns with phi-psi angles near (90,0)
Term
q
Definition
side chain contains an amide group
Term
dG
Definition
alternates with deoxycytosine to form Z-DNA
Term
D
Definition
side chain is contains only one CH2, pKa ~4
Term
V
Definition
Isosteric to (same shape as) threonine
Term
U
Definition
nucleotide base that is the deamination product of 5-methyl cytosine
Term
A
Definition
is most stabilizing for alpha helices
Term
Y
Definition
phenolic side chain found in topoisomerase active sites
Term
C
Definition
cross-links polypeptides in the presence of oxygen
Term
K
Definition
has a basic side chain that contains a primary amino group
Term
H
Definition
side chain pKa is near physiological pH
Term
R
Definition
contains three nitrogens, pKa ~12
Term
3 structural properties of alpha helices and beta strands
Definition

compacted conformation

Hbond minimizes free energy and minimizing backbone torsional energies

minimize excluded volume and surface tension

Term
secondary structure
Definition
regular structures characterized by repeating backbone torsion angles and maximal backbone H-bonds
Term
loop
Definition
protein segment that does not adopt compact "regular" 2* structure
Term
A-form
Definition
most common geometry of RNA helix
Term
base step
Definition
two consecutive base pairs
Term
Holiday junction
Definition
a four way junction created from two (nearly)-identical DNA duplexes
Term
alpha helix
Definition
3.6 residues/turn and etends 1.5 A/residue
Term
sequence motif
Definition
conserved sequence patterns that indicate a specific fold or function
Term
orthologs
Definition
proteins from a different organisms with a similar functions
Term
major groove
Definition
provides the widest access to the basepairs in B-DNA helices
Term
node
Definition
where DNA duplexes cross in a loop or supercoil
Term
turn
Definition
connect two polypeptide sequences with mininal loss of H-bonds
Term
Stacking interactions
Definition
result of London dispersion forces between planar bases
Term
helical repeat
Definition
a protein sequence pattern that places residues on one side of an alpha helix
Term
tertiary interactions
Definition
3-D contacts between residues that are far apart in sequence
Term
multimer
Definition
a protein complex, contains more than one subunit
Term
fold
Definition
classification of the 3-D path of a polypeptide of RNA
Term
duplex
Definition
double stranded DNA or RNA
Term
tetraloop receptor
Definition
binds to GNRA loops in folded RNAs
Term
beta strand
Definition
contains almost 2 residues/turn and extends 3.2-3.4 A/residue
Term
minor groove
Definition
contains the cytosine O2 and adenine N3 atoms, arrow in   A-tracts
Term
what drive duplex formation DNA
Definition
Duplex formation is driven by base stacking. In the ssDNA only 70% stacked while B DNA, they are 100%. The base H bonds provide no stabilization, but do provide specificity. Cations minimize the repulsion between phosphate
Term
T/F compared to a 2.5 A crystal structure, a 5 crystal structure has twice the definition
Definition
F
Term
T/F CryoEM images are of good quality because of their high contrast
Definition
F
Term
T/F Electron microscopy can, in theory, have as high a resolution as Xray crystallography
Definition
T
Term
T/F Electron microscopy is a good technique for studying ez catalytic mechanisms
Definition
F
Term
T/F Crystallography is a good way to study filamentous proteins
Definition
F
Term
telomeres
Definition
quadraplex DNA
Term
oxidation of cysteine
Definition
S-OH and converts from non polar to polar, disrupt hydrophobic connection
Term
Charged acidic
Definition
Asp, Glu
Term
Polar amides
Definition
Asn, Gln
Term
Charge basic
Definition
Arg, Lys, His
Term
Hydrophobic (hydrocarbon side chain)
Definition
Ala, Val, Ile, Leu, Phe
Term
Hydrophobic(contains small side chain)
Definition
Cys, Met, Pro, Tyr, Trp
Term
Sequence => structure
Definition
same sequence will have the same structure
Term
Secondary structures
Definition
helices, strands, turns, loops
Term
supersecondary structure
Definition
connect 2* structure elements together (turns and loops)
Term
why secondary structure?
Definition
relaxed torsion angles, compactness, cooperativity, relaxed torsion angles, main chain H bonds are satisfied
Term
Cooperativity of helix assembly
Definition
Limiting step = formation of the first turn. Adding the next residue is easier
Term
Helix folding
Definition
all or nothing process
Term
alpha helix
Definition
the terminal 3 Os and HNs are not satisfied in H bonding.
Term
consequence of extended strand
Definition
Peptide bonds of adjacent residues point in opposite directions. Side chains are in opp direction. no intra strand hydrogen bonding
Term
Twist
Definition
B strands have a right hand twist -> b sheets have a left hand twist
Term
Turns
Definition
Supersecondary structure,short peptides, redirect chain with minimal loss of H bonds. Fairly rigid, WELL DEFINED GEOMETRY.
Term
Loops
Definition
can be floopy, varies in structures and length. OFTEN CONTAIN IMPORTANT INTERACTION SURFACES (ACTIVE SITES)
Term
Domain
Definition
A unit of "stand alone" protein structure. Compact, contiguously self interacting, and is able achieve its structure without additional interactions (at least in some protein, somewhere). Usually associated with a particular function.
Term
Protein fold
Definition
the path of the polypeptide bacbone of an entire protein or "domain". Could be a collection of domains
Term
tertiary structures
Definition
collections of interacting secondary structures connected by super secondary structures. May contain several motifs.
Term
A folding motif
Definition
A well defined (and usually conserved) collection of several secondary structures. Usually smaller than a domain, but sometimes interchangeable
Term
A sequence motif
Definition
a sequence pattern, contiguous or interrupted, that is a "signature" of a folding motif and or domain. Indicative of a particular function-functional residues are the most conserved.
Term
Sequence alignment
Definition
the best match of two or more sequences believed to be related, based on identity, homology or structure. Some gaps are allowed
Term
Sequence identity
Definition
the % of exact residue matche within a set of sequences after alignment(random 5%)
Term
Sequence homology
Definition
the % of close residue matches (based on chemical or genetic similarities)after alignment. More generous than identity
Term
Homologs
Definition
proteins that are related in sequence and/or structure, and overall functions
Term
Isoforms
Definition
proteins that have the same biological function but slightly different sequences. Can be coexpressed or have organelluar or tissue-specific expression
Term
Paralogs
Definition
set of proteins that have similar biochemical activities but separate biological functions, contain homologous domains
Term
Protein folds
Definition
similar folds = similar functions. It also could indicate convergent/divergent evolution, does not mean same sequence
Term
Tertiary structure classification
Definition
CATH: class, architecture, topology, and homologous superfamily.
Term
3* STRUCTURE
Definition
dominant type of 2*structure
Term
3*Architecture
Definition
overall shape and relative positioning of 2*structural elements. ARRANGEMENT
Term
3*Topology
Definition
the order and nature of the connections (loops and turns)between 2*structural elements. CONNECTION PATH OF ARRANGEMENT
Term
3*Homologous superfamily
Definition
Members are believe to have elvolved from a common ancestor based on sequence and/or structural similarity
Term
Parallel beta sheet core
Definition
creates a cylinder, satisfies backbone H-bonding. Barrel interior is not hollow-packed with hydrophobic sidechain
Term
Filament
Definition
At least two interaction surfaces(heterologous association). Head-to-tail interactions. Cannot close a ring. Usually super-helical.
Term
Homo-oligomer
Definition
at least two interaction surfaces(except dimer). Head-to-tail interactions, head-to-head(oligomerization domains), closes a ring, can be symmetric or asymmetric dimer, trimer, tetramer, hexamer.
Term
Oligomeric interface
Definition
>600A, charge distribution, types of interface:interdigitation, hydrophobic surface, polar interaction(salt bridge,H-bond,water bridge)
Term
Quasi equivalence
Definition
when one protein can have more than 1 aggregation state. Usually utilizes a mixture of shared and new interfaces. Often seen in virus capsids. UNUSUAL.
Term
Hetero-Oligomer
Definition
similar to homo except more than oen subunit type:-asymmetric multimer(G protein), pseudo-symmetric(hemoglobin),symmetric multimer of asymmetric multimers(ATCase)
Term
Complex multimer
Definition
more than one subunit type in a mostly asymmetric or mixed symmetry/asymmetry(ribomose, RNA polymerase, ATP synthase complex)
Term
Why form oligomers?
Definition
1) Increased Stability/Resistance to mutations. 2)Regulation(allostery,"checkpoint")3)Higher specificity due to larger interaction surface(DNA BP)
Architectural (actin/myosin)
Term
Interfacial active sites
Definition
when more than one monomer donates residues to form a single active site due to evolution
Term
Nucleoside
Definition
base + ribose
Term
Nucleotide
Definition
base + ribose +phosphate
Term
phosphate
Definition
active forms linked to 5'OH of sugar. 2' or 3'linked forms are products of degradation
Term
Base labile
Definition
cleaves backbone
Term
Acid labile
Definition
causes: 3-2 migration, depurination
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