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This module contains motivational and biochemical background material for a computer scientist beginning to learn about computational structural biology.

    Topics in this module

  • Proteins and Their Significance to Biology and Medicine
  • Protein Structure
  • Experimental Methods for Protein Structure Determination
  • Protein Structure Repositories
  • Visualizing Protein Structures

Proteins and their significance to biology and medicine

Proteins are the molecular workhorses of all known biological systems. Among other functions, they are the motors that cause muscle contraction, the catalysts that drive life-sustaining chemical processes, and the molecules that hold cells together to form tissues and organs.

The following is a list of a few of the diverse biological processes mediated by proteins:

  • Proteins called enzymes catalyse vital reactions, such as those involved in metabolism, cellular reproduction, and gene expression.
  • Regulatory proteins control the location and timing of gene expression.
  • Cytokines, hormones, and other signalling proteins transmit information between cells.
  • Immune system proteins recognize and tag foreign material for attack and removal.
  • Structural proteins prevent cells from collapsing on themselves, as well as forming large structures such as hair, nails, and the protective, largely impermeable outer layer of skin. They also provide a framework along which molecules can be transported within cells.

The estimate of the number of genes in the human genome has been changing dramatically since it was annotated (the latest gene count estimates can be found in this Wikipedia article on the human genome ). Each gene encodes one or more distinct proteins. The total number of distinct proteins in the human body is larger than the number of genes due to alternate splicing . Of those, only a small fraction have been isolated and studied to the point that their purpose and mechanism of activity is well understood. If the functions and relationships between every protein were fully understood, we would most likely have a much better understanding of how our bodies work and what goes wrong in diseases such as cancer, amyotrophic lateral sclerosis, Parkinson's, heart disease and many others. As a result, protein science is a very active field. As the field has progressed, computer-aided modeling and simulation of proteins have found their place among the methods available to researchers.

Protein structure

An amino acid is a simple organic molecule consisting of a basic (hydrogen-accepting), amine group bound to an acidic (hydrogen-donating) carboxyl group via a single intermediate carbon atom:

An α-amino acid

A generic α-amino acid. The "R" group is variable, and is the only difference between the 20 common amino acids. This form is called a zwitterion, because it has both positive and negatively charged atoms. The zwitterionic state results from the amine group (NH2) gaining a hydrogen atom from solution, and the acidic group (COO) losing one.
During the translation of a gene into a protein, the protein is formed by the sequential joining of amino acids end-to-end to form a long chain-like molecule, or polymer . A polymer of amino acids is often referred to as a polypeptide . The genome is capable of coding for 20 different amino acids whose chemical properties depend on the composition of their side chains ("R" in the above figure). Thus, to a first approximation, a protein is nothing more than a sequence of these amino acids (or, more properly, amino acid residues , because both the amine and acid groups lose their acid/base properties when they are part of a polypeptide). This sequence is called the primary structure of the protein.

A polypeptide

A generic polypeptide chain. The bonds shown in yellow, which connect separate amino acid residues, are called peptide bonds .
The Wikipedia entry on amino acids provides a more detailed background, including the structure, properties, abbreviations, and genetic codes for each of the 20 common amino acids.

Questions & Answers

A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
Aislinn Reply
cm
tijani
what is titration
John Reply
what is physics
Siyaka Reply
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Jude Reply
Can you compute that for me. Ty
Jude
what is the dimension formula of energy?
David Reply
what is viscosity?
David
what is inorganic
emma Reply
what is chemistry
Youesf Reply
what is inorganic
emma
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
Krampah Reply
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
Sahid Reply
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
Samuel Reply
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Joseph Reply
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
Ryan
what's motion
Maurice Reply
what are the types of wave
Maurice
answer
Magreth
progressive wave
Magreth
hello friend how are you
Muhammad Reply
fine, how about you?
Mohammed
hi
Mujahid
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
yasuo Reply
Who can show me the full solution in this problem?
Reofrir Reply
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Source:  OpenStax, Geometric methods in structural computational biology. OpenStax CNX. Jun 11, 2007 Download for free at http://cnx.org/content/col10344/1.6
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