L-Cysteine

[yousuf89]

Can any one give me a stereochemical structure of L-Cysteine by using the Fischer convention and indicate whether it is the R or S configuration?

Please!!

I've searched every website for two days and no detail the L-Cysteine (well the things that I wanted).

[MBGuru]

R/S naming system is based on the Cahn–Ingold–Prelog rules, while the L/D naming system is based on the Fisher projections. These two naming systems are independent of each other.

 

Of all naturally occurring L-amino acids, Cysteine and Selenocysteine are the only ones that are in R configuration, the rest of them are in S.

[Horza2002]

Remember that Cahn-Ingold-Prelog rules are just rules. Because cystein has sulphur and selenocystein has selenium the side chains override the priority of the carboxylate group

[yousuf89]

yeah, but what's does it look like and is L-Cysteine a R configuration?

[Horza2002]

It will look exactly the same as all the other amino acids but with the releavent functional group. Presemebly you have the structure of serine...it will be exactly the same but replace the hydroxy with a thiol

[yousuf89]

It will look exactly the same as all the other amino acids but with the releavent functional group. Presemebly you have the structure of serine...it will be exactly the same but replace the hydroxy with a thiol

 

can u show me please or give me a link that have the structure?

[Horza2002]

http://www.cem.msu.edu/~reusch/VirtualText/proteins.htm

 

This website explains it rather well. If you look on the right hand side, theres a Fischer projection of gylcine...just replace the central hydrigen R group with the relavant thiol to get cystein