yousuf89 Posted March 7, 2010 Share Posted March 7, 2010 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). Link to comment Share on other sites More sharing options...
MBGuru Posted March 7, 2010 Share Posted March 7, 2010 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. Link to comment Share on other sites More sharing options...
Horza2002 Posted March 7, 2010 Share Posted March 7, 2010 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 Link to comment Share on other sites More sharing options...
yousuf89 Posted March 7, 2010 Author Share Posted March 7, 2010 yeah, but what's does it look like and is L-Cysteine a R configuration? Link to comment Share on other sites More sharing options...
Horza2002 Posted March 7, 2010 Share Posted March 7, 2010 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 Link to comment Share on other sites More sharing options...
yousuf89 Posted March 7, 2010 Author Share Posted March 7, 2010 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? Link to comment Share on other sites More sharing options...
Horza2002 Posted March 7, 2010 Share Posted March 7, 2010 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 Link to comment Share on other sites More sharing options...
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