[AlBourne88]

Im really stuck on finding out the bond angles between the atoms of glyine.

I really don't know anything so any help would be appreciated!

Thanks

[templelane]

Right on this page you can see the structure
Glycine - Wikipedia, the free encyclopedia

What level are you at high school uni etc? Because that will depend on how I think you should approach this problem.
Have you done hybridisation and VSEPR yet? Orbital hybridisation - Wikipedia, the free encyclopedia
If you have that's how I'd work out the angles. First I would look at the structure, the look at the bonds to work out the hybridisation states. From these the propable angles could be deduced.

Hope this gives you a starting point, post back if you haven't got a clue what I'm on about!

[AlBourne88]

Im in uni doing a biology degree, and haven't done any chemistry before now... im doing a module in chemistry to catch up though and have some knowledge of bond angles etc, but not very much!
We have done VSEPR a little bit but I really don't know how to work out the bond angles seeing as I have never been given any example of bond angles in amino acids before.
If you could tell me how I'm supposed to work this out it would be of great help, I've looked around the internet and there doesn't seem to be anything on the bond angles in amino acids.

Thanks sooo much for your help!

[templelane]

Ahh that narrows it down a bit! You're in luck it's my field.

Right if it is for amino acids there are three main angles
the phi, psi and omega angles
omega between the C1 (the C=O) and N is always around 180 degrees
phi is between the N and C alpha [I remember this by N-H = pHI]
psi is between C alpha and C1
Here's a pic angles

Phi and Psi can change as they are single bonds which can rotate. However due to steric hindrance (when atoms electron denisities clash) they tend to cluster around several different angles. These can be plotted on a graph known as the Ramachandran plot. Ramachandran plot - Wikipedia, the free encyclopedia
As you can see the angles cluster in two main areas one is for the alpha helix secondary protein structure and the other the beta sheet. I have put up wikipedia (again!) because it labels this.

Glycine being a small amino acid is actually quiet flexible and has more outlying phi and psi angles compared to other amino acids. Have another look at the chart- the green bits for this amino aid as it is less restricted.

Have you ever heard of PyMol? You should download it PyMOL Home Page it's free. Then go to the protein databank (RCSB Protein Data Bank) download a random pdb file and you can play with it and look at the angles and protein secondary structure.

I could talk about this until I go blue in the face so any questions fire away.

[AlBourne88]

Is the information you gave me on angles only for amino acids in a peptide chain?

The question I have been asked to do is: use your knowledge of covalent bonding in molecules and electron pair repulsion theory to explain and predict the bond angles between all the atoms of glycine, for example, the N-H-C bond angle and the O-C-C bond angles.

I am not sure whether this means whilst glycine is linked with other amino acids or just finding bond angles for the individual amino acid of glycine. In lectures we have only really been shown the 'regular' bond angles of things like methane etc. never amino acids.

I think I know what the N-H-C and O-C-C bonds are, but don't have a clue how to work out the angles! This question is really driving me crazy!!

If your last answer is answering this question then can you please tell me that the answer you gave me is correct and I apologise for not understanding...

Thanks sooo much for your help.

[templelane]

Hmm, put like that I think it must be the VSEPR theory they want you to use, in my second post I was talking about amino acids in a chain specifically.

I have just found the perfect page for you, it really is impossible just to explain this in words! http://www.docbrown.info/page06/molecule_shapes.htm Look through this page and then look at the bonding in glycine, draw in lone pairs if it helps, then label each bond.

For example the alpha carbon is tetrahedral sp3 bonded, therefore the angles are 109.5 degrees.

The 'scribbles' at the botom of the page are basically what you have to do except with your molecule.

PS when drawing out the structure of glycine to label don't forget to draw in the hydrogens!

[rajeshAQW]

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