Structure and Function of Proteins?

Question

I am looking for somebackground info on this area and any good related websites. i would like to learn more on this area of proteins, espeically the monomer and polymer structures. Also the relationship between the structure and functions
thank you

Answer 1

The properties of a protein are determined by its covalently-linked amino acid sequence, otherwise known as its primary structure. Depending on the nature and arrangement of the amino acids present, different parts of the molecule form secondary structure such as the alpa helices or beta sheets shown below. Further folding and reorganisation within the molecule results in higher order or tertiary structure.
Secondary and tertiary structure represents the most thermodynamically stable conformation (or shape) for the molecule in solution, and results from non-covalent interactions (ionic bonds, hydrogen bonds, hydrophobic interactions) between the various amino acid side-chains within the molecule and with the water molecules surrounding it. Different regions of the protein, often with distinct functions, may form structuraly distinct domains. Structurally related domains are found in different proteins which perform similar functions.
The exposed surface of the protein may also be involved in interactions with other molecules, including proteins. Protein-protein interactions, for example between sub-units of enzyme complexes or polymeric structural proteins, results in the highest level of organisation, or quaternary structure.
The functions are:
Enzymes - biological catalysts.
Immunoglobulins - antibodies of immune system.
Transport - move materials around hemoglobin for O2.
Regulatory - hormones, control metabolism.
Structural - coverings and support skin, tendons, hair, nails, bone.
Movement - muscles, cilia, flagella.
If you really want to research this subject in depth Google "Structiure and Functions of Proteins"

Answer 2

This is a very broad question.
Proteins perform the majority of the biochemical functions (enzymes, receptors, etc etc) carried out in living cells: DNA codes for proteins. Proteins do the work.

The function is mostly determined by the amino-acid sequence (read from the DNA) and by the 3D structure it adopts when the linear chain folds itself up.

How it folds up is still an unresolved question with many people working and publishing in this area. There is probably at least one Nobel prize waiting for the person who can write a computer program that can accurately predict protein structure from the amino-acid sequence alone. I suspect that in many cases this will never be acheived, and that the best approaches will still make predictions based on similarity to other, similar proteins of known structure.

There are many books on the matter, but most of the ones I have read are probably too technical for you (Alan Fersht one of the most famous scientists/authors in this area).

Answer 3

OK there is so much information on protein structure and function available (I'm writing a 200 page PhD thesis on a very tiny part of it) but here are some websites that cover the basics. They are both websites designed to help undergraduates alongside their lectures so have good basic but full information available. They are both clearly written so you should be able to understand if you are doing an essay for A-level as well.

http://webhost.bridgew.edu/fgorga/proteins/default.htm
http://www.bmb.uga.edu/wampler/tutorial/prot0.html

If you type in protein structure in google there are lots of examples of similar pages. Look for something on university pages then you can be sure it will be reliable and in depth.

Answer 4

There are basically 3 kinds of cell membrane proteins: associated ones (loosely connected to the membrane), embeded ones (one part is anchored to the membrane) and transmembrane proteins (one part is inside the cell one in the membrane and one sticking out) the cell membrane is a charged lipid bilayer with the negative and watery part facing out - so any part of a protein beeing inside a membrane has to be negatively charged and/or be lipophillic. The domains of proteins in a membrane or crossing it are typically alpha helices. functions are manifold - for transmembrane proteins the most common are channel or receptor. Channel transport molecules across the membrane and have to be gated to close the cell - often a bundle of helices making a small pore. receptors reach across but make no opening in the cell wall - the perfom a structural change upon binding of a ligand which leads to activation inside the cell. membrane bound proteins are often places of synthesis or are helping transmembrane proteins (an example would be G- protein coupled receptors) - basically the same goes for membrane associated proteins with them beeing able to cycle from and to the membranes (an example would be the SecA transporter) basic structures: associated and bound proteines have often a catalytic center where they convert ATP or GTP whereas transmembrane proteins lack these