Proteins are the macromolecules responsible for the biological processes in the cell. They consist at their most basic level of a chain of amino acids, determined by the sequence of nucleotides in a gene. Depending on the amino acid sequence (different amino acids have different biochemical properties) and interactions with their environment, proteins fold into a three-dimensional structure, which allows them to interact with other proteins and molecules and perform their function
Proteins are the macromolecules responsible for the biological processes in the cell. They consist at their most basic level of a chain of amino acids, determined by the sequence of nucleotides in a gene. Depending on the amino acid sequence (different amino acids have different biochemical properties) and interactions with their environment, proteins fold into a three-dimensional structure, which allows them to interact with other proteins and molecules and perform their function
Primary structure of protein
Secondary structure of protein
Tertiary structure of protein
Quaternary structure of protein
Methods to determine protein structure
Conclusion
References
METHODS TO DETERMINE PROTEIN STRUCTURE
Each protein has a unique sequence of amino acids.
The amino acids are held together in a protein by
covalent peptide bonds or linkages.
A peptide bond are formed when amino group of an
amino acid combines with the carboxyl group of another.
The conformation of polypeptide chain by twisting or folding is referred to as secondary structure.
Two types of secondary structures α-helix and β-sheet are mainly identified.
α-Helical structure was proposed by Pauling and Corey in 1951.
It occurs when the sequence of amino acids are linked by hydrogen bonds.
Each turn of α-helix contains 3.6 amino acids.
β-pleated sheets are composed of two or more segments of fully extended peptide chains.
β-Sheets may be arranged either in parallel or anti-parallel direction.
Many globular proteins contain combinations of α-helix and β-pleated sheet secondary structure, these patterns are called supersecondary structures also called motifs.
The three dimensional arrangement of protein structure is referred to as tertiary structure.
It is a compact structure with hydrophobic side chains held interior while the hydrophilic groups are on the surface.
This type of arrangement provide stability of the molecule.
Besides the H-bongs, disulfide bonds, ionic interactions, hydrophobic interactions also contribute to the tertiary structure.
Gives in detail primary, secondary, tertiary and Quaternary structure of proteins. Gives classification of secondary structure: alpha helix, beta pleated sheet and different types of tight turns and explains most commonly found tight turn in proteins i.e. beta turn. Briefs about the Ramachandran plot of proteins, dihedral or torsion angles and explains why glycine and proline act as alpha helix breakers. Explains tertiary structure of proteins and different covalent and non covalent bonds in the tertiary structure and relative importance of these bonding interactions. Details about the quaternary structure of proteins and explains why hemoglobin is a quaternary protein and insulin is not.
Primary structure of protein
Secondary structure of protein
Tertiary structure of protein
Quaternary structure of protein
Methods to determine protein structure
Conclusion
References
METHODS TO DETERMINE PROTEIN STRUCTURE
Each protein has a unique sequence of amino acids.
The amino acids are held together in a protein by
covalent peptide bonds or linkages.
A peptide bond are formed when amino group of an
amino acid combines with the carboxyl group of another.
The conformation of polypeptide chain by twisting or folding is referred to as secondary structure.
Two types of secondary structures α-helix and β-sheet are mainly identified.
α-Helical structure was proposed by Pauling and Corey in 1951.
It occurs when the sequence of amino acids are linked by hydrogen bonds.
Each turn of α-helix contains 3.6 amino acids.
β-pleated sheets are composed of two or more segments of fully extended peptide chains.
β-Sheets may be arranged either in parallel or anti-parallel direction.
Many globular proteins contain combinations of α-helix and β-pleated sheet secondary structure, these patterns are called supersecondary structures also called motifs.
The three dimensional arrangement of protein structure is referred to as tertiary structure.
It is a compact structure with hydrophobic side chains held interior while the hydrophilic groups are on the surface.
This type of arrangement provide stability of the molecule.
Besides the H-bongs, disulfide bonds, ionic interactions, hydrophobic interactions also contribute to the tertiary structure.
Gives in detail primary, secondary, tertiary and Quaternary structure of proteins. Gives classification of secondary structure: alpha helix, beta pleated sheet and different types of tight turns and explains most commonly found tight turn in proteins i.e. beta turn. Briefs about the Ramachandran plot of proteins, dihedral or torsion angles and explains why glycine and proline act as alpha helix breakers. Explains tertiary structure of proteins and different covalent and non covalent bonds in the tertiary structure and relative importance of these bonding interactions. Details about the quaternary structure of proteins and explains why hemoglobin is a quaternary protein and insulin is not.
Structure of protiens and the applied aspectsMohit Adhikary
The slides explain the structures of proteins, the bond stabilizing the structure of amino acids, the different types of protein structures, the applied aspects and the newer advances in the protein structure.
A detailed explanation of cloning strategies which involves isolation of DNA fragments from the sample and introduction in to a vector with restriction enzymes and introduced in to host by different methods and finally screening of the host cells with the recombinants based on protein,nucleicacid and antibiotic assays
control of gene expression by sigma factor and post transcriptional controlIndrajaDoradla
explanation of control of gene expression by sigma factor and decription of sigma factor and detailed explation of post transcriptional control by antisense technology and rna i
description of transgenic animals and production with desired traits using different methods and their applications and their advantages and disadvantages
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Seminar of U.V. Spectroscopy by SAMIR PANDASAMIR PANDA
Spectroscopy is a branch of science dealing the study of interaction of electromagnetic radiation with matter.
Ultraviolet-visible spectroscopy refers to absorption spectroscopy or reflect spectroscopy in the UV-VIS spectral region.
Ultraviolet-visible spectroscopy is an analytical method that can measure the amount of light received by the analyte.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
2. The structure of protein is organized in to 4 levels of organization they are:
• Primary structure
• Secondary structure
• Tertiary structure
• Quaternary structure
• These levels also reflect their temporal sequence.
• Proteins are synthesized as a primary sequence and then fold into secondary →
tertiary → and quaternary structures.
3. Primary structure of proteins
• It was given by sanger
• Primary structure of protein refers to the linear sequence and arrangement of
amino acids in polypeptide chain.
• Amino acids are building blocks of proteins. The amino acids are linked with each
other with the help of Peptide bond to form a peptide (or) Protein
• Thus bond is formed between -NH2 group of one amino acid and -COOH group
of the next amino acid.
• During peptide bond formation, one water molecule will be eliminated, hence it is
called as dehydration synthesis.
• The end at which –COOH group is free is called C-terminal and other end at
which –NH2 group is free is called N-terminal of polypeptide chain
• Due to partial double bond character between –CO and –NH group, they do not
rotate
4.
5. • The primary structure of protein is stabilized by peptide bonds and disulphide
bonds.
• These are strong covalent bonds.
• The disulphide bond is formed between cysteine residues.
Eg: insulin
insulin Contain 51 Amino aids which are arranged in 2 peptide chains
A chain - 21 Amino acids
B chain - 30 Amino acids
These two chains an linked by disulphide bonds.
6. Secondary structure of Proteins
• It was given by Linus Pauling and Robert Corey in 1951 by using X-ray
diffraction studies
• Amino acids that are located near to each other interacts to form regular
arrangement called secondary structure.
• The secondary structure of protein is more compact and stable than primary
structure
• The secondary structure of proteins is stabilized by hydrogen bonds
• The hydrogen bond is between the “o” atom of c=o group of one amino acid and
H atom of N-H group another amino acid polypeptide chain
There are three commonly occurring secondary structure. They are;
• α-Helix
• β-sheet
• β-bends or β-turn
7. α-helix structure:
• α-helix is a right handed helical structure formed by twisting of polypeptide chain.
• It is a spiral structure.
• Each helix in α-helix structure contains 3.6 aminoacids residues. Vertical length of each
helix is known as pitch which is 5.4 Å. Therefore, the vertical distance between two
nearest aminoacids is 1.5Å.
• In α-helix, -C=O group of each aminoacid is hydrogen bonded with –NH group of other
aminoacid which is situated four amino acid ahead. Which is (i+4) or (n+4) arrangement
• Therefore, -C=O and –NH group of all aminoacids are hydrogen bonded in α-helical
structure.
• R-group of aminoacid in α-helix are projected outward to minimize steric hindrance
• Some aminoacids disrupt α-helix. For examples, the aminoacids with charged R-group
disrupt α-helix by electrostatic repulsion or by formation of ionic bond. Similarly
aminoacids with bulky R-group disrupt α-helix by steric interference.
• Aminoacids glycine and proline bring bend in polypeptide chain and disrupt α-helix
9. β-sheet structure:
• β-Sheet is the most stable form of secondary structure of protein.
• It is formed between two different polypeptide chains which are placed parallel or
antiparallel to each other.
• It can also be formed by folding of same polypeptide chain.
• In β-sheet structure, two polypeptide backbone are linked with each other by H-bond
which are formed between –CO and –NH group.
• R-group of amino acids are alternately projected above and below the plane of β-sheet.
• The surface of β-sheet is not straight but it is pleated. Therefore, it is also known as β-
pleated sheet.
• Polypeptide backbone in β-sheet is extended rather than being tightly coiled as in α-
helix.
• The axial distance between two nearest amino acid is 3.5 Å in contract with 1.5 Å in α-
helix.
• In β-sheet hydrogen bond may be inter chain or intra chain but they are always inter
chain in α-helix.
11. • β-bends or β-turn structure:
• β-bend reverse the direction of polypeptide chain and helps it to form globular
(spherical ) structure.
• Β-bend structure consists of at least 4 amino acids in which nth amino acid is
hydrogen bonded with (n+3)th amino acids.
• Glycine and proline are always found in β-bend structure.
• Ring of Proline attached with α-carbon atom helps to bend the chain. Similarly,
lack of R-group in glycine permits great degree of rotation around α-carbon atom
and bring bend in the polypeptide chain.
12.
13. Tertiary structure of protein:
• It was given by John Kendrew and his colleagues in 1980 by using X-ray analysis
• It is more compact and folded structure than Secondary structure
• Tertiary structure refers to the overall folding of a polypeptide chain to form a
final three dimensional structure.
• For example, a globular protein which are larger than 200 amino acids units forms
two or more domains by folding of polypeptide chain by either α-helix, or β-
pleated sheet or β-bend. Finally these domains associates with each other to form
final 3D structure.
• Therefore, tertiary structure refers to the formation of these domains by overall
folding of polypeptide chain and then final association of these domains to form
globular 3D structure
14. • This protein structure is mostly stabilized by non covalent interactions they are
• Hydrophobic interactions
• Hydrophilic interactions
• Vanderwal interactions
• Hydrogen bonds
• Disulphide bonds
Hydrophobic interactions
• These are weak bonds. These are formed in a polypeptide chain in between the
nonpolar R group containing aminoacids
Hydrophilic interactions
• These are weak bonds. These are formed in a polypeptide chain in between the
polar R group containing aminoacids
15. Vanderwal interactions
• These are weak bonds. These are formed in a polypeptide chain in between the
hydrophobic aminoacids
Hydrogen bonds
• These are weak bonds. These are formed in a polypeptide chain in between the
NH2 & C=O groups
Disulphide bonds
• These are strong covalent bonds. These are formed in a polypeptide chain in
between the cysteine-cysteine aminoacids
16. Quaternary structure of protein:
• It was given by max Perutz and john kendrew in 1959
• Some proteins are composed of more than one polypeptide chain. Each
polypeptide chain in such protein are called sub-units.
• The quaternary structure refers to interaction between these sub-units to form
large final 3D structure. Therefore, quaternary structure is interaction between
different polypeptide chains of multi chain protein.
• Quatarnary structure is found only in protein which are composed of more than
one polypeptide chains such as hemoglobin
• Bonds like H-bond, ionic bond, hydrophobic interaction helps to from quaternary
structure.
• Examples of quaternary structure of protein are hemoglobin, DNA polymerases
and ion channels.
17.
18. Denaturation
• The native proteins are said to be the proteins occurring in animal and plant
tissues.
• They possess many characteristic properties such as solubility, viscosity, optical
rotation, sedimentation rate, electrophoretic mobility etc.
• For an oligomeric protein, denaturation may involve dissociation of the protomers
with or without subsequent unfolding or with or without undergoing changes in
protomer conformation.
Denaturation of Proteins:
• Denaturation may be defined as the disruption of the secondary, tertiary and
quarternary structure of the native protein resulting in the alterations of the
physical, chemical and biological characteristics of the protein by a variety of
agents.
19. Denaturing Agents:
1. Physical agents:
• Heat, surface action, ultraviolet light, ultrasound, high pressure etc
2. Chemical agents:
• Acids, alkalis, heavy metal salts, urea, ethanol, guanidine detergents etc. Urea and
guanidine probably interfere with the hydrogen bonds between peptide linkages in
the secondary and tertiary structure of proteins
• Physical Alterations:
• Many proteins, especially of the globular type, can be crystallized in the native
state.
• But denatured proteins cannot be crystallized
• Chemical Alterations:
• The denatured protein is greatly decreased in solubility at its isoelectric point due
to disruption of native configuration
20. • Acid and alkali disrupts hydrogen bonds in protein
• Urea, detergents disrupt hydrophobic bonds in protein
• β mercapto ethanol and performic acid disrupts disulphide bonds between
cysteine residues
• Biological Alterations:
• The digestibility of certain denatured proteins by proteolytic enzymes is increased.
• Enzymatic or hormonal activity is usually destroyed by denaturation.
• The antigenic or antibody functions of proteins are frequently altered
Irreversible
denaturation
21.
22. • If the denaturation is severe, the protein molecules become insoluble and
precipitation results as well as the changes in the properties of the proteins are
permanent and “irreversible”.
• In case of mild denaturation, there is “reversible denaturation” leading to the
slight changes in the properties of the protein which can be restored to the native
state after suitable treatment
• Significance:
1. The precipitation of the native protein as a result of denaturation is used to advan-
tage in the clinical laboratory.
2. Blood or serum samples to be analysed for small molecules (e.g., glucose, uric
acid, drugs) generally are first treated with acids such as trichloroacetic acid,
phosphotungstic acid or phosphomolybdic acid to precipitate most of the proteins
present in the sample.
• This is removed by centrifugation and the protein-free supernatant liquid is then
analysed.
23. Renaturation
• The process by which the denatured proteins regain their native confirmation is
called renaturation
• The denaturation is reversible in some cases
• It is carried out by Christian Anfinsen in 1951
• Example : Bovine ribonuclease contain 124 A.A . It is native configuration
When the protein is treated with 8m urea and β-mercaptoethanol is denatured and
produce 8 cysteine residues urea disrupt the hydrophobic interaction of Rnase where
as β-mercaptoethanol disrupts the disulphide bond
24. • When the Rnase is free from the urea β-mercaptoethanol by dialysis it is slowly
regain its enzymatic activity and contain 4 disulphide bonds
• RNase RNase RNase
Urea + β-
mercaptoethanol
filteration
Urea + β-mercaptoethanol
